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Medium Voltage Application Guide

1. The compact size of the power assembly leaves room for auxiliary equipment to be installed The phase cassette should be mounted at the bottom of the enclosure and the Controller can be mounted on the front panel The diagrams below illustrate a possible configuration for installation o ml r Ug l q ci z oE a LT e Vu n j pe A WS D RENS m k Reeg x D gt 3 E S p mmis in s Pati Pati Pas A o 7 i z Front view Side view Rear view Il Controller compartment Upper LV compartment 6 Bypass contactor circuit breaker Surge arrester 8 Phase cassette power connections Main contactor circuit breaker compartment 9 Earth switch Input supply terminals 710 12280 00A Medium Voltage Application Guide Page 39 SOFT STARTERS Soft starter communication options AuCom medium voltage soft starters can connect easily to Modbus Profibus or DeviceNet communication networks using simple add on communication interfaces All communication interfaces allow you to e control the soft starter e monitor the starter s o
2. Indoor room testing 1175 T The room is simulated by a floor ceiling and two walls perpendicular to each other NE WI sus i 00 Accessibility 2 BB ee 9 Type A restricted to authorised personnel Type B unrestricted accessibility F front access L lateral side access 1239 R rear access IAC certification example IAC classification AF E EE Internal Arc 31 5 kA Is 300 Y LLLLLLLLLLL LLL 710 12280 00A Medium Voltage Application Guide Page 85 SWITCHGEAR Causes of internal arc There are many potential causes for internal arcing within metal enclosed switchgear Some of the more common Causes are e foreign matter in the enclosure eg vermin metal swarf tools e contamination and general degradation of insulation material e inadequate insulation of cable terminations e overheating of termination points due to inadequate preparation and tightening e system overvoltage e incorrect protection settings and coordination Locations causes and examples of measures to decrease the probability of internal faults Locations where internal faults are most likely to occur Cable compartments Disconnectors Switches Earthing switches Bolted connections and contacts Instrument transformers Possible causes of internal faults Inadequate design Faulty installation Failure of solid or liquid insulation defective or missing Maloperation Circuit breaker
3. l M3 i i E Gegen EN E re i FON NEUEN EE Q30B I e 1 i 4 f lu i I I i i 13530 A 2 Output bus Main output circuit breaker withdrawable T Motor start circuit breaker fixed Mj Meer S otor bypass circuit breaker fred M3 Ier otor 2 start circuit breaker fixed Electronic motor starter SST or VFD otor 2 bypass circuit breaker fixed Master controller PLC or part of Al otor 3 start circuit breaker fixed otor 3 bypass circuit breaker fixed Page 62 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Auto mode operating sequence NOTE In this example the master controller A2 has been preselected to start the motors in order 2 3 then stop them in the reverse order Starting control sequence With the entire system enabled for Auto mode operation main input circuit breaker QI is closed 2 The master controller A2 issues a system start command The main output circuit breaker Q2 closes 3 Motor start circuit breaker Q IOA closes then after a delay the starter A starts motor and takes the motor to full running speed e fora soft starter full running speed is assumed when the motor s running current is equal to or less than motor full load current e fora VFD full running speed is assumed when the output freq
4. 710 12280 00A Medium Voltage Application Guide Page 147 SWITCHGEAR Exercise For a motor running at full load calculate the full load current the total electrical input power and the amount of full load slip given that Pr 2000 kW U 33 kV 50 Hz eff 0 95 p f 0 88 N 485 rpm poles 4 Motor full load current Input power alternative calculation Motor slip at full load FLC gt o __ V3 xU xpf x eff 2000 43 x3 3x 0 88 x 0 95 _ 2000 4 78 418A P n 8xU xFLCxpf 3x3 3x418x0 88 2105 kW Pan P pef H ar H et _ 2000 0 95 2105 kW ez slip fx120 poles _ 50x120 N x 1 slip 1 slip 1 N N 1485 1500 1 0 99 0 01 p u Page 148 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Busbar calculations verify the thermal and electrodynamic design limits and check that no resonance will occur Busbar Calculations Thermal withstand Rated current I A The rating of a busbar system depends on the material shape size and configuration of the individual busbars as well as the operating conditions The calculated busbar rating per phase must be greater than the maximum expected operating current 24 9x 0 0 y gx poss Where OCH Jare 20 maximum allowable current per phase
5. Inside delta connection 12996 A e Simplifies replacement of star delta starters because the existing cabling can be used e May reduce installation cost Soft starter cost will be reduced but there are additional cabling and main contactor costs The cost equation must be considered on an individual basis Only motors that allow each end of all three motor windings to be connected separately can be controlled using the inside delta connection method Not all soft starters can be connected in inside delta Page 28 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS 3 4 AuCom Medium Voltage Soft Starters MVS Soft Starter Overview The MVS provides compact and robust soft start solutions for control of medium voltage motors MVS soft starters provide a complete range of motor and system protection features and have been designed for reliable performance in the most demanding installation situations Each IPOO MVS soft starter comprises two elements e a power assembly e a controller module The power assembly and controller module are supplied as a pair and share the same serial number Care should be taken during installation to ensure the correct controller and power assembly are used together Each MVS is also supplied with two fibre optic cables to connect the controller module to the power assembly and three non conduction lead assemblies allowing the soft starter to be tested with a
6. contactor 4kAS8kA The fuse is suitable for use with the contactor Page 98 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR e The nominal current setting of the curve is set for the motor FLC In this case set overload protection so that 120 A The overload curve hot curve needs to lie outside the motor start curve and intersect with the fuse curve at a point before the maximum breaking current of the contactor K D K U B Oeean or O oeae Ks i Q Step 3 Select an overload curve i ing In Contactor maximum break current lc Contactor thermal withstand curve Time s 13525 A Current A 710 12280 00A Medium Voltage Application Guide Page 99 SWITCHGEAR Medium Voltage Switches Medium voltage switches for use on kV to 52 kV indoor systems are predominantly used for isolation and earthing Although the majority of these switches are air insulated gas insulated SF6 combination switches are available which are designed for load and fault current switching Operation of a switch can be manual or motorised International standards provide maximum torque levels required to operate manual disconnect and earth switches There must be a visual indication of the switch position by viewing the contacts or an indicator driven land from the ee Switch ype Disconnector Rated for carrying continuous load current with fixed or withdrawable a short time withstand f
7. E 0 550 55 17 0 250 E 10 548 54 8 0 E 20 545 53 3 0 200 g 30 541 53 5 0 ae 40 537 55 8 0 50 531 58 10 0 100 60 525 61 14 0 5 70 518 67 19 0 s s o mn o aie 500 77 23 0 j be a Tn 90 475 110 30 0 0 10 20 30 40 50 60 70 80 90 95 100 lt 95 425 160 34 0 Motor speed 3 100 100 100 37 0 be Motor current amp torque curves at 3 5 x FLC Load Motor speed Motor current Motor torque Load torque accelerating 700 350 as of atspeednas at speed n as at speed n as torque at rated speed motor FLC motor FLT motor FLT speed n as motor FLT 600 300 Cnn Tm Tn Tan c 500 SE Ld 350 22 17 0 5 D E o 350 22 80 E z E 350 22 3 0 19 g g 350 22 50 m o Ios 350 23 80 15 350 25 10 0 15 d 10 350 27 14 0 13 S 350 81 19 0 12 190 a A E 350 38 230 15 LR 0 0 t Tin 6 90 350 60 30 0 30 0 10 20 30 40 50 60 70 80 90 95 100 E 9596 350 109 34 0 75 Motor speed 8 100 100 100 37 0 0 2 Acceleration time calculations 1 5 x FLC 2 0 x FLC 2 5 x FLC 3 0 x FLC 3 5 x FLC Motor Speed Average Load Acceleration Average Load Acceleration Average Load Acceleration Average Load Acceleration Average Load Acceleration as Rated Accelerating Time Over Accelerating Time Over Accelerating Time Over Accelerating Time Over Accelerating Time Over Speed Torque Over Speed Rangen Torque Over Speed Rangen Torque Over Speed Rangen Torque Over Speed Range
8. 100 65 9 0 19 80 2 0 16 83 0 0 15 83 0 0 15 83 0 0 15 5 secs 4 secs 3 secs 2 secs 2 secs Page 56 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Calculations performed by software Revised motor torque T srp This calculates the torque that the motor will supply at a reduced level of start current Calculations use percentages of full load torque and full load current 700 4 2 l 600 4 200 em Tanta M 500 4 400 7 Where 300 4 100 sm revised motor torque ootd m motor torque level at full voltage start DAN 100 e lag motor start current limit level 8 motor current level at full voltage start 40 20 30 40 B0 Sit 709 80 90 400 Speed full speed Example At 50 motor speed calculate the revised motor torque for a start current limit of 400 FLC a DOL current level of 600 FLC and a DOL motor torque level of 20 FLT 400 Ton 120x i E 53 FLT Acceleration time calculation This calculates the time that the motor will take to accelerate from one speed to another specified speed typically calculated in 10 increments of motor full load speed The total acceleration time from standstill to full load speed is the sum of all incremental speed steps Calculations use actual values lan su T T 55 x Ty esl 500 7 Where ado Lu time to accelerate from one speed to another seconds
9. 198235 A 100 79 371A Start Current and Torque Curve Analysis To accurately calculate an application s start current requirements torque and current curves for both the motor and the load are required Information from these curves is used to assess the minimum start current requirements With the following information specific application software can accurately estimate the minimum required start current Istr and start time tc e Motor datasheet including kW full load speed and motor shaft inertia e Motor speed current curve e Motor speed torque curve e Load speed torque curve e Load inertia 710 12280 00A Medium Voltage Application Guide Page 55 SOFT STARTERS Motor load and application data Application Data Motor kW Full speed rpm Total load inertia at motor shaft kg m2 Current and torque curve data 3200 1481 168 Motor speed Motor current Motor torque Load torque as of at speed n as at speed n as at speed n as rated speed motor FLC motor FLT motor FLT 350 7 9 9 300 n Cnn Tm 26 T
10. 2 6 x for a 60 Hz supply with a Du 7 ees n rms symmetrical fault current level with no DC component 45 ms DC time constant 3 kA Source IEC 62271 1 IEC 62771 100 MV earth switches tend to have a maximum I of 82 kA Electrical endurance class This class defines the fault making capability of earth switching devices EO Standard electrical endurance No fault making capability EI Extended electrical endurance Capable of 2 fault making operations without damage E2 Highest electrical endurance Capable of 5 fault making operations without damage Mechanical endurance class This class defines the mechanical endurance of no load disconnectors MO Standard electrical endurance 1000 operating cycles without maintenance MI Extended electrical endurance 2000 operating cycles without maintenance M2 Highest electrical endurance 10000 operating cycles without maintenance 710 12280 00A Medium Voltage Application Guide Page 103 SWITCHGEAR Medium Voltage HRC Fuses Medium voltage high rupturing capacity HRC fuses are constructed of narrow conductor bands which are shaped to melt in overload or short circuit conditions The conductor bands are configured in a spiral embedded in quartz sand filling and totally sealed within a high thermally resistive ceramic housing Each end of the fuse has either end caps for fi Although fuses provide a form of overload pro prot
11. AC symmetrical fault current component kA k DC fault current component kA Standard values for I 6 3 8 10 12 5 16 Percentage DC component in fault current 100 90 80 70 60 50 40 30 20 Percentage DC component 10 0 NEZ T4 120 ms Sue ite eae 13 75 ms P Ge To 60 ms eee Tu 45 ms 0 5 10 15 20 2 30 35 40 45 50 55 60 65 70 75 80 85 90 Time interval from initiation of short circuit current ms 20 25 31 5 40 50 63 kA source IEC 62271 100 13720 A The graph illustrates the percentage DC component of a fault over a period of time for systems with various time constants Most systems use the standard time constant t of 45 ms The total opening time of the circuit breaker is the pole opening time plus 10 ms for relay sensing and this figure can be used to determine the percentage DC component of a fault at the instant of breaking Page 92 Mediu m Voltage Application Guide 710 12280 00A SWITCHGEAR Exercise The percentage Percentage DC component la 7 lx Jte 20585 21x SEN 21 1 086 23 kA The asymmetrical fault current level is 23 kA A circuit breaker with a rated short circuit breaking capacity L of 25 KA can be used Total opening time of the circuit breake DC component at a to 100 What is
12. Page 96 Medium Voltage Application Guide 710 12280 00A IEC Ratings Medium voltage contactors must be type tested to provide standard ratings The contactor nameplate label must show the manufacturer s name contactor model and serial number and certain rating information Many manufacturers also provide additional rating information MV contactor rating information Description Maximum operating voltage rms the device can continuously withstand during normal operation The rated voltage must be greater than or equal to the system s operating voltage Standard values for U 3 6 7 2 12 17 5 24 36 kV source EC 62271 1 Insulation voltage kV Power frequency withstand voltage is an indication of the insulation strength of the contactor U This rating must match the system s operating frequency Maximum allowable continuous current without the contactor temperature rise limits being exceeded Rated operational cu t when being used for a specific tilisation category Maximum making current m A imum making current without welding or adverse on of contact material Maximum breaking current L A mum breaking current without welding or adverse on of contact material time withstand current t rms which can be sustained in the closed ion before external short circuit protection opens the Short time withstand peri Time that the contactor can sustain before dama
13. e magnetic technique uses an open and close armature permanently energised in one of the two states The energy required to maintain constant magnetic field strength in either the open or closed state is stored using capacitance Energised armatures interact with mechanical linkages to operate the main switching contacts This operating technique provides extremely fast operation and is very energy efficient e stored energy technique incorporates an opening and closing spring Each spring is charged with potential energy by motor operation or by using a manually operated handle in case of auxiliary power loss Mechanical operation of the main switching contacts occurs by releasing the potential energy from a charged spring Spring release is activated electrically by the use of small opening and closing solenoids or by manual pushbuttons which operate mechanical latches Withdrawable circuit breakers Most indoor switchgear installations use withdrawable circuit breakers These are also referred to as rack style or draw out units DOU The main circuit breaker body is fitted on a trolley arrangement known as a truck which is moved horizontally by means of a crank handle By moving the circuit breaker towards the operator the main contact points separate until a test position is reached To reconnect the main contact points the circuit breaker is moved away from the operator until the service position is reached The circ
14. 100x10 80x10 80x6 80x5 80x3 50x10 50x8 50x6 50x5 S cm2 10 8 4 8 4 2 4 5 4 3 2 5 m Cu 0 089 0 071 0 043 0 036 0 021 0 044 0 036 0 027 0 022 daN cm A5 L 0 027 0 022 0 013 0 011 0 006 0 014 0 011 0 008 0 007 KR l cm4 0 83 0 66 0 144 0 083 0 018 0 416 0 213 0 09 0 05 x I v cms 1 66 1 33 0 48 0 33 0 12 0 83 0 53 0 3 0 2 teer EEN cm 83 33 4266 256 21 33 12 8 1041 8 33 6 25 5 2 x Iv cm 16 66 10 66 6 4 5 33 3 2 4 16 3 33 2 5 2 08 Il x Il cm4 21 66 17 33 3 74 2 16 0 47 10 83 5 54 2 34 1 35 X I v cm3 14 45 11 55 4 16 2 88 1 04 7 22 4 62 2 6 1 8 B Ss cm4 166 66 85 33 51 2 42 66 25 6 20 83 16 66 12 5 10 41 x lv cm3 33 33 21 33 12 8 10 66 6 4 8 33 6 66 5 4 16 ill B ill cm4 82 5 66 14 25 8 25 1 78 41 25 21 12 8 91 5 16 x lv cem 33 26 4 9 5 6 6 2 38 16 5 10 56 5 94 4 13 x Ss cm4 250 128 76 8 64 38 4 31 25 25 18 75 15 62 EUM I cm3 50 32 19 2 16 9 6 12 5 10 7 5 6 25 14009 A Source Schneider Electric 2000 Page 154 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Exercise A busbar system has two end mounted busbars per phase jj om ge made of 4 hard copper maximum allowable stress of rg 8 1200 daN cm Each bar is 8 cm high and cm wide with a gap of cm between bars of the same phase The phase centres are 15 cm and each phase has 6 insulator stand offs at 80 cm spacing The insulator stand offs are 15 cm high 9 with a b
15. If this value is likely to be exceeded extra inductive reactance must be installed in line with the capacitor bank This not only reduces the peak inrush current but also dampens the effect of transient overvoltages which occur at switch on Fuse pre melt figures and the making capacity of associated switchgear need to account for the expected peak inrush current Inrush reactors 13811 A Inrush reactors are constructed of a primary coil encapsulated in a resin case Classified as an air core inductor they are rated according to the following electrical characteristics e nominal voltage kV must be equal to or greater than the system voltage e nominal current A must be equal to or greater than the capacitor bank nominal current e inductance uH Calculations Re rating a capacitor bank for specific voltage To re rate the power Q of a capacitor bank to match a specific system voltage Where Q Tu 2 Q re rated capacitor bank power at required system voltage oj NU ss j Q capacitor bank power at manufacturer s specified nominal Q end voltage kVAr 2 U system voltage U capacitor bank nominal voltage Exercise A capacitor bank has a nominal power rating of 500 kVAr at 7 2 kV Calculate the re rated capacitor bank power if used on a 6 6 kV system 2 EL Up 2 500x se 72 Q Q x 500 x 0 92 500 x 0 84 420 kVAr The re rated power at 6 6 kV is 420
16. Maximum discharge current the MO arrestor can shunt to earth without exceeding its thermal and mechanical limits Manufacturers usually state two discharge current ratings e Current produced as a result of a lightning strike voltage transient This discharge current is assumed to be an 8 20 us waveform with the following standard ratings 1 5 kA 2 5 kA 5 kA 10 kA 20 kA For the majority of secondary indoor switchgear systems a rating of 10 kA is used for selection sometimes referred to as distribution class e Current produced as a result of an equipment switching voltage transient This discharge current is assumed to be a 30 60 us waveform with standard ratings from 125 A to 1000 A For the majority of secondary indoor switchgear systems a rating of 500 A is used for selection sometimes referred to as distribution class wn Continuous operating voltage Uc This is based on the maximum peak operating voltage likely to occur in the system when a single phase to earth fault occurs IEEE standards refer to this rating as MCOV maximum continuous operating voltage For a solidly earthed neutral system U U 21 05 x Z V3 For a high impedance or isolated earthed neutral system U 2 U s Where U system phase to phase line voltage kV Rated voltage U This rating is based on the thermal capabilities of the MO arrestor to endure short term overvoltage transients exceeding the continuou
17. Possible for user to open but not intended to be for normal operation and maintenance Special accessible compartment ossible for ed to Non accessible compartment user to open not be opened Switchgear classification with regard to the loss of service continuity when opening accessible compartments LSCI LSC2 LSC2A LSC2B Switchgear classification with regard to the nature of the barrier between live parts and opened accessible compartment Switchgear classification with regard to mechanical electrical and fire hazards in case of internal arc during normal operation Source IEC 62271 200 ocking to be combined with operator rocedures to allow access only when HV arts are dead and earthed necessary for opening No specific provision to address access procedure Special procedures may be required to maintain performances Opening destroys compartment or clear indication to the user Accessibility not relevant D D Tools Features Other functional units or some of them shall be disconnected Other functional units can be energized Other functional units and all cable compartments can be energized Features Metallic shutters and partition between live parts and open compartment metal enclosed condition maintained Insulation covered discontinuity in the metallic partitions shutters between live parts and open compartment Features No ej
18. Rated primary current I A 1 25 of nominal source current Incomer from transformer l2 0 2 0 1 25 of transformer s rated primary current 0 2 3 P Feeder to transformer pr 5 of motor full load current 1 5 of nominal capacitor current Feeder to motor D Feeder to capacitor bank lpr Rated secondary current A Use A and 5 A for local installation Use A for remote installation Real output power VA The real output rating of the CT must be the next highest nominal size above the expected total burden on the CT secondary Total burden is the sum of output cable connectors and instruments 710 12280 00A Medium Voltage Application Guide Page 113 SWITCHGEAR Class type Use a metering class CT for metering and indication A higher class CT gives greater accuracy between the primary and secondary currents Use a 5PX protection class CT for current based protection relay inputs The ALF must be selected so that the relay trip point lies on the linear part of the secondary current curve between 50 and 100 of the ALF Page 14 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Exercise Select appropriate CTs for the following transformer incomer and feeder circuits H Transformer Incomer e MV MV transformer TXRI 5 MVA 36 11 kV 10 Z e Instantaneous overcurrent trip setting 15 x l for digital protection relay OC driven off CT1 2
19. Sub states 3 States tl Main contactor close time SI Ready t2 Rotor resistance contactor close time 92 Precstart tests t3 Bypass contactor close time 3 Starting 2 Output voltage S4 Running VI 100 voltage 4 Phases of operation V2 Slip ring retard voltage PI Start command P2 Rotor resistance current ramp P3 Shorted rotor current ramp Rotor resistance sizing When using a soft starter for slip ring motor starting a single stage three phase resistance bank must be used For an existing installation with a multi stage resistance bank the existing final stage resistance can normally be used To specify a new single stage resistance bank use the following guideline Slip ring rotor resistance sizing formula Where U R 202x Bi P Bx U P P 0 2x SUE P Pa rotor resistance per phase Q open circuit rotor voltage V rotor current A power rating of rotor resistance per phase kW motor shaft power KW Slip ring synchronous motors Although they are rare there are some older synchronous motors which use a special double winding rotor One winding set is used for standard slip ring rotor starting The other winding set is a synchronous speed running These motors can be started using a soft starter with fina synchronisation package This package is supplied separate DC excitation winding used for stage resistance but the control system must include a y to
20. The equipment shall permit the operator to reload a previously saved configuration set from an internal file There shall be two files available The equipment shall permit the operator to restore default settings The equipment shall support remote management via a control network with a choice of Modbus Profibus and Devicenet as a minimum The equipment shall provide an on board real time clock but failure of this clock due to low battery shall not trip the starter LOGIC CONTROL CONFIGURATION 3 2 Operating Configurations The equipment shall permit the user to select between multiple profiles for starting the motor The equipment shall provide a kickstart option for starting the motor The equipment shall permit the user to select between multiple profiles for stopping the motor The equipment shall provide a feedback ramp option for stopping the motor The equipment shall provide a means of automatically stopping the motor at a predetermined time or after a predetermined period of operation The equipment shall be suitable for use with dual speed and slip ring motors Thermal modeling that allows the soft starter to dynamically calculate the motor temperature predict the motors available thermal capacity to predict whether the motor can successfully complete a start 3 3 Motor and System Protection Features The starter shall have the following adjustable protection functions included as standard ANSI
21. The secondary windings of each set of C Ts shall be earthed at one point C Ts for protective purposes shall be of the nominated protection Class rated burden and saturation factor sufficient to cater for the normal relay settings and load burdens required in the protection scheme Current transformers used for metering and indicating instruments shall have accuracy not less than the nominated typically Class 0 5 and Class 1 0 respectively Each transformer shall be capable of providing the necessary VA to operate the related instruments 3 12 Labels 1 2 3 Each item of equipment shall carry the manufacturer s rating plates with information and compliance with the relevant standard Further labelling shall be provided to indicate the main functions of each service and control equipment item All wiring terminal positions and terminations shall be identified by local labels to indicate the group services e g closing tripping etc This shall be in addition to the cable ferrule method 3 13 Control Wiring 1 2 3 Suitably rated terminal blocks shall be provided for all external cable connections Terminals for circuits carrying different voltages shall be segregated labelled and separated with insulating barriers Control cabling inside electrical panels shall be with PVC V105 insulated stranded single core copper cable The minimum cross section shall be suitable for the load current and volt drop for CT secondary
22. 1050 lt 1500 A Use protection class 5P 0 710 12280 00A Medium Voltage Application Guide Page 17 SWITCHGEAR NEMA IEEE Ratings These ratings are typically used for current transformers manufactured or used in North American installations As well as a stated primary to secondary nominal current ratio the device also carries an overall accuracy rating in the format Where AC accuracy class CR class rating BU maximum burden ohms AC CR BU Accuracy class Designates the accuracy of the secondary current with respect to the primary rated current This accuracy is only guaranteed provided the maximum burden is not exceeded Accuracy class Tolerance at 10076 primary current t 1 296 0 6 0 5 0 3 Class rating Designates the intended application of the device B for metering applications H for protection applications The CT secondary accuracy is guaranteed at 5 to 20 times the nominal primary rated current Burden The maximum load allowed to be connected to the current transformer secondary to guarantee the accuracy class The maximum burden includes secondary cable wire connectors and the load The following table converts burden in ohms to VA for a 5 A secondary 0 5 B 0 indicates a current transformer with an accuracy of 0 5 and a maximum allowable secondary burden of 0 1 Q or 2 5 VA ona 5 A secondary CT This is a metering class rated current tran
23. T h total inertia of the motor rotor and load coupled together kg m To convert GD to kg m divide by 4 E An speed difference from nl to n2 rpm 1007 T average acceleration torque from nl to n2 Nm See r Acceleration torque is the difference between the developed EE Sc torque and the required load torque as seen at the motor Speed full speed sha 710 12280 00A Medium Voltage Application Guide Page 57 SOFT STARTERS Example Calculate the acceleration time of a 2000 kW motor driving a pump load from 40 to 50 full speed The full load speed is 2990 rpm Average acceleration torque from 40 to 50 full speed is 20 motor FLT The motor shaft inertia is 60 kg m and the pump inertia is 12 kg m Total inertia is motor plus load inertia J 60 12kg m 72kg m Speed difference is 1076 of full load speed An n2 n1 x full load speed 50 40 x 2990 rpm 299 rpm Average acceleration torque is 20 of motor FLT or kW 2000 x 9550 2990 6388 Nm 20 Tey wy 6388x 1278 Nm Calculate the acceleration time from 40 to 50 full load speed J xAn let geb i _ 72kg m x 299 rpm 9 55 x 1278 Nm 21528 12205 1 76 sec Page 58 Medium Voltage Application Guide 710 12280 00A 3 7 Special Applications SOFT STARTERS Forward Reverse motor starting Forward and reverse operation is required for applications where it is necessary ofthe machinery as
24. e Electromagnetic ammeter A is driven off CTI 1 H Transformer Feeder e MV LV transformer TXR2 2 MVA 1 1 0 4 kV 5 Z e nstantaneous overcurrent trip setting 10 x for digital protection relay OC2 driven off CT2 13703 A Exercise Metering CT for transformer incomer circuit Step Calculate transformer TXRI nominal secondary current A S BE 9000 Bea 262 A The secondary current for TXRI is 262 A Step 2 Calculated maximum expected short circuit current at CT installation L A Ignoring any power cable or busbar impedances E 3 262x100 10 2620 A The maximum expected short circuit current at CT I is 2620 A ls Step 3 Select metering CT 1 ratings Primary rated current 1 0 1 25 x1 1 0 1 25 x 262 A Use a rating of 300 A Secondary rated current Use a rating of A Short time withstand rating li 2 l Use a rating of 10 kA Primary circuit voltage U 2 U Use a rating of 12 kV Real output power typically gt 3 VA for electromagnetic type meter Use 5 VA this allows 2 VA for cable burden etc Accuracy Class Use Class 1 0 common class for general metering 710 12280 00A Medium Voltage Application Guide Page 115 SWITCHGEAR Exercise 2 Protection CT 1 2 for transformer incomer circuit Step Select ratings common to both the metering and protection CTs Primary secondary rated current
25. from 630 A to 2000 A An IAC classification of 31 5 kA for second is achieved by double skin e compartments special locking door designs and top exit arc flaps for pressure release Direct Incomer Panel DIP Typical Direct Incomer Panel Iesst Iesst 11175A Front view Side view Rear view ol Current transformer set Earth switch 3 Voltage transformer fused and withdrawable 710 12280 00A Medium Voltage Application Guide Page 75 SWITCHGEAR Bus Coupler Panel BCP A bus coupler panel connects two adjacent horizontal busbar systems together normally a withdrawable type which is housed in its own compartment of the system of metal enclosed switchgear is usually situated towards the top of the p physically connect two adjacent busbar systems together a bus coupler panel m panel A main earth switch current and voltage transformers and low voltage equipme extras GR AuCom provides a Bus Coupler Panel as part of its L Series switchgear ys 630 Ato 2000 A An IAC classification of 31 5 kA for second is ach using a main circuit breaker panel The horizontal busbar anel enclosure In order to ust be used alongside a bus riser nt can all be supplied as optional range This is rated at 12 kV from ieved by double skin S compartments special locking door designs and
26. lt O jus 3 Ch ch S CO E H Wd a mi e Q A zy ioa anical interlock sbar GPO3 bushing plates crew bushings horizontal busbar small large nternal copper work Horizontal busbar copper work and joints Earth bars co Earth bar links Rear cover Fixings for rear cover Panel builder check sheets eys for all access doors Earth switch handle tandard VCB racking handle rr Rear busbar chamber covers and fixings CH e 9 o o joining bolts supplied Page 162 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Electrical Inspection Location Date nspection staff Cubicle serial number Contract Electrical schematic drawing number Control voltages required for testing Description Passed Comments YIN LV door apparatus HERES Voltage indicators EE Selector switches c eys for selector switches Fortress or other Pushbuttons ndicators colours Control device door labels functions Device numbering internal Terminal numbering CT test block assemblies VT test block assemblies M WV Check MCB ratings Power supply ratings and operation 10 VAC distribution 220 VAC distribution 10 VDC distribution 24 VDC distributi LV door earth lin 2 LEO Ed ch O 5 eaters and the mostats hz eater operation Check CT rating plates Earth connection at CTs Check VT rating p
27. too ett tct ted Lt s tette 8 INTRODUCTION Introduction 1 1 1 2 1 3 General This Section defines the general requirements for MV switchgear and associated electrical works This specification used in conjunction with purchase documents data sheets and or drawings establishes the minimum requirements for the design fabrication and testing of the switchgear aspects of the work for the Plant e Reference to other industrial standards for compliance shall be interpreted as an integral part of this specification e The Contractor Supplier shall be responsible for obtaining from the Client all necessary approvals and information required to complete the Works e All electrical work shall be carried out in accordance with local regulations or other recognized international standards e The approval of equipment and material by the relevant authority shall not prejudice the rights of the Client to reject such equipment or material that does not comply with the specification e f required the Contractor Supplier shall engage professionally qualified specialists experts to carry out any special activities associated with the provision of special electrical equipment and to comply with all local relevant regulations Submission The Contractor Supplier shall submit designs drawings data documents and other such information as specified and required for the Client s review All submittals shall
28. 05 kA 8 82 kA l Transient stage LAE Zox Zue Zen 7 Ze Lert Zr 1 6x0 72 1620 72 20 500 Subtransient stage NL E _1 2x0 72 7 2 5x14 11 4240 72 235 28 kA 20 450 A D Bl Source Network U 36kV S 1000 MVA Transformer TR 36 kV kv 50 Hz 20 MVA Z IO Motor M U kv 50Hz P 2000 kw For the purposes of this calculation ignore all impedances of circuit breakers cables and busbars The first step is to calculate the individual impedances Page 160 Medium Voltage Application Guide 710 12280 00A Motor impedance Zy Transformer impedance Zp Network impedance Ze as seen on the u U 2 secondary side of the transformer Zwer RE SWITCHGEAR 25 EE 11 200 2000 1240 The motor impedance is 12 Q Eg Z R Us 490 1f 10 E 20 100 0 610 The permanent impedance is 0 6 Q pr U 36 JI 1000 36 1 300 317 0 120 p The permanent impedance is 0 12 Q Short circuit impedances and ratings of switchgear devices Device Equivalent circuit Short o E Break rating Make rating kA E kA peak Zsc Zerf Zir 0 12 0 6 0 72 Q Lux Zyer Zra Aer Zra 12 1x0 72 1240 72 0 680 ls Bun on 20 96 0 525 kA 525A 11 sc 7 _ 11 EI 8 82 kA B 1
29. 29 MYX Soft Startelin to hA RR p lE EATA ENAA AE 34 Eelere CEET Ee ee 40 Predictive Maintenamee Module RIMM i RID c RO e ad A 42 3 5 RE HIE 43 ee EE 43 Switehgear Requ lhemebtsssoseie ceti ea DRM ERR EELER 45 ACDS UBlisationodess lt os a te E ses Lost tL ut E eL num 52 3 6 Gal CULATIONS cocti oa ttt e a Pct 54 What is the minimum start current with a soft starter n 94 Calculating required start current for new or existing AC induction motor installations 3 Special Applications Forward Reverse motor starting 2299 Multi motor starting 6 AuCom multi motor starting solution Slip ring motor COMPO M NER mS 66 3 8 Common standards for MV soft starters and switchgear panels nnns 68 710 12280 00A Medium Voltage Application Guide Page CONTENTS 4 PONTE SAN setae EE AY QUU ADLER ela 69 4 SWitehgear eege 70 EC Switchgear Classificati Onoda curta d RP UR E nd vn Rd en m edd ue H ANS defined Switch gears suit tote tct t tq eret ue dtt 72 Switchgear Rate enee ea ed cla taeda ede laan eu 72 Switchgear information for enquiries or ordering erret 72 Switeheeal deratllig ee eade eM RM MU ME M MU 73 42 Standard Enclosure Configura ti ns Ae 74 eege Feeler Fail E sc o ts d dee DUM CMM 74 Directe INCOME Rane ue 1D Bus Goupler Panel BGP 3 aot erben stil ael bu e to t
30. 4 4 DB2 AUTO mode Providing power sources NI and N2 are healthy NI will supply network DBI and N2 will supply network DB2 Bus coupler S will remain open f power source NI is lost this supply is isolated and bus coupler S is closed Power source N2 now supplies networks DBI and DB2 Once power source NI is re established bus coupler S is opened and NI will supply network DBI and N2 will supply network DB2 f power source N2 is lost this supply is isolated and bus coupler S is closed Power source NI now supplies networks DBI and DB2 Once power source N2 is re established bus coupler S is opened and NI will supply network DBI and N2 will supply network DB2 MANUAL mode Select NI and N2 as power sources with bus coupler S open Select power source NI with bus coupler S closed and power source N2 isolated Select power source N2 with bus coupler S closed and power source NI isolated 710 12280 00A Medium Voltage Application Guide Page 177 SCHEMATIC DIAGRAMS 5 5 MVS Schematic Diagrams The MVS medium voltage soft starter is rated for 80 A to 321 A at 2 3 kV to 7 2 kV AuCom can supply the soft starter in an IP54 or IP42 style panel with two switchgear configurations These are referred to as E3 and E2 panel options E3 panel option The standard E3 panel option consists of a combined main isolator earth switch a main and bypass contactor and a set of MV fast acting
31. 5 307 18 3 13 M1 41 7 33 8 377 442 204 32 0 33 3 17 5 14 36 7 44 8 38 4 436 ars 317 34 5 36 8 18 8 15 393 481 39 6 51 0 339 36 8 38 4 200 16 419 513 5 416 544 352 39 4 410 213 17 5 545 442 57 8 384 418 435 225 18 47 2 57 7 652 668 522 512 407 m3 461 238 18 430 eos 668 494 85 1 64 6 439 465 KL 25 0 20 524 64 1 724 52 0 580 68 0 452 492 61 2 26 3 21 5 0 613 760 54 6 en 714 475 17 538 2 22 57 6 70 5 784 57 2 636 74 0 4907 541 63 788 23 60 3 737 83 3 55 8 657 78 2 520 6 6 49 300 24 62 9 EI 86 9 62 4 696 816 543 7 1 58 1 614 33 5 65 5 801 905 65 0 725 85 0 555 565 61 6 640 26 68 1 534 4 1 70 754 88 4 555 019 40 665 27 70 7 556 v7 70 2 765 61 6 610 KEE 68 4 89 1 350 28 73 4 8985 1014 72 8 812 85 2 633 86 7 66 5 17 35 3 28 76 0 30 1080 75 4 84 98 6 656 6290 714 74 2 37 8 w 70 6 96 2 100 6 70 0 67 102 0 78 714 738 768 388 31 81 2 9934 1122 00 6 599 105 4 70 1 ns KE 79 3 40 0 32 83 9 1 026 1158 83 2 928 108 8 723 76 2 78 7 81 413 3a 86 5 105 8 119 5 65 6 9857 112 2 746 706 ma 84 5 426 M 89 1 108 0 1231 hia 386 115 5 769 GO 83 7 87 0 43 6 36 981 7 1122 126 7 81 0 101 5 115 8 79 1 033 55 1 Dap 36 54 3 1164 130 3 83 6 104 4 122 3 BIA 7 06 6 92 1 63 37 7 0 118 6 1340 08 2 107 3 125 7 837 88 1 91 1 E47 47 50 M 9 0 121 0 137 6 08 8 1102 129 1 859 90 5 93 5 97 3 48 40 38 102 2 125 0 1412 1014 EA 192 5 862 928 96 0 958 5000 40 104 8 128 2 144 8 1040 1160 135 8 904 9 2 88 4 1024 5130 4t 1074 1314 1484 1055 118 9 135 3
32. 50 Access with a finger test finger 12 mm mm diameter 80 mm length IP2X Protected against solid objects greater than 12 5 Access with a finger test finger 12 mm mm diameter 80 mm length IP2XC Protected against solid objects greater than 12 5 Access with a tool test rod 2 5 mm diameter mm 00 mm length IP2XD Protected against solid objects greater than 12 5 Access with a wire test wire 1 0 mm diameter mm 00 mm length IP3XC Protected against solid objects greater than 2 5 Access with a tool test rod 2 5 mm diameter mm 00 mm length IP3XD Protected against solid objects greater than 2 5 Access with a wire test wire 1 0 mm diameter mm 00 mm length IP4X Protected against solid objects greater than Access with a wire test wire 1 0 mm diameter mm 00 mm length IP5X Protection against harmful entry of dust Access with a wire test wire 0 mm diameter 00 mm length Source IEC 6227 Page 170 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR NEMA Ratings NEMA 250 is a product standard that addresses many aspects of enclosure design and performance NEMA Protection against solid objects Closest IP equivalent ndoor protection from contact P 20 2 ndoor limited protection from dirt and water P22 3 Outdoor some protection from rain sleet windblown dust and ice P55 3R Outdoor some protection from rain sleet and ice P 24 4
33. 6000 A I load Internal voltage drop U int _ Hoad x Z int 1000 6000 x 0 28 1000 1680 1000 21 68 kV U int The internal voltage drop is 1 68 kV Secondary output voltage due to overload U U E U int 7 33 1 68 5 65 kV The secondary output voltage Is 5 65 kV Output voltage drop U U 6 6 5 65 0 95 kV The output voltage drop is 0 95 kV or 14 U Page 146 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR op Motor Calculations P_IN P_LOSS P_OUT Where Input power Ply d s sept PLn electrical input power kVV Output power P ou P _x eff D A mechanical output shaft power kW Pour Nat P ios motor losses KW ie iron copper 9550 magnetic friction windage losses Motor losses P jos zb w P oan U motor rated supply voltage kV Paos zP ggx d 1 f nominal rated supply frequency Hz Motor efficiency eff P on eff motor full load efficiency p u i P N FLC motor full load current A Motor full load current FLC Poe pf motor full load power factor p u V3 x U xp f x eff N motor full load speed rpm Motor full load speed N zN x 1 slip N motor synchronous speed rpm Motor synchronous speed H fx120 poles number of motor stator poles B poles T full load motor shaft torque Nm slip motor slip at full load p u
34. 825 A For motor starting current of 825 A at 2 starts per hour the required motor rated fuse is 250 A 3 6 kV Page 108 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Motor circuit coordination Consider the following motor branch circuit Motor circuit with fuse and contactor FA 13696 A The circu gg pee o LB eere B oem N 5 pee RK er Time s 13783 A Current A Coordination requirements e The expected motor start current curve 1 must sit inside to the left of the thermal relay protection curve 2 and the fuse trip curve 3 e The intersection of the thermal relay protection curve and the fuse trip curve must have a lower current value that the maximum breaking current of the contactor 4 e The fuse rating must not exceed the maximum size stated by the contactor manufacturer e The thermal withstand curves of the motor 5 and the cable 6 must sit outside to the right of the thermal relay protection curve and the fuse trip curve e The short circuit withstand current rating of the contactor must exceed the expected rms short circuit current downstream of the fuse after current limiting e Ifa back up fuse is installed upstream its minimum l t value must be greater than the maximum l t value of the motor branch fuse 710 12280 00A Medium Voltage Application Guide Page 109 SWITCHGEAR Current Transformers A current transform
35. 827 87 6 1008 1048 5250 42 130 1 1346 1521 1092 121 8 1427 950 1000 1034 107 5 5380 42 27 137 9 155 7 me 1247 146 1 972 1024 1056 110 1 Source example data based on ABB MWD surge arrestors 710 12280 00A Medium Voltage Application Guide Page 135 SWITCHGEAR Power Factor Capacitors Power factor correction PFC capacitor banks are used to improve the overall power factor of a medium voltage distribution system or an individual installation 13808 A Bulk power factor correction This is installed at the point of common coupling which is typically on the main busbar system in a medium voltage network If the loading on the network was constant with a fixed inductance bulk power factor correction could be of a fixed value and permanently connected to the system However this is often not the case Most network loading is variable and if the bulk of the load is inductive the amount of power factor correction required to maintain a target power factor also needs to vary This is achieved by using a master PFC controller which monitors the system s power factor and switches in nominal values of capacitance as needed to maintain a target value Circuit with bulk power factor correction o PFC controller Individual power factor correction A very common method of maintaining a target power factor for a motor is to install an individual power factor bank of fixed capacitance The PFC bank is specifically sized fo
36. A K total coefficient factor e e 0 maximum allowable busbar temperature C 3 0 nominal ambient temperature lt 40 C p20 resistivity at 20 C copper 1 83 uQ cm aluminium 2 90 uQ cm a temperature coefficient of resistivity 0 004 a P busbar perimeter 2 e a cm S busbar cross section e a cm D 8 The permitted busbar temperature rise is defined in IEC 62271 1 Maximum permissible temperature rise for bolt connected devices including busbars Material and dielectric medium Maximum permissible Temperature rise temperature C above 40 C ambient CO ted connection or equivalent re copper bare copper alloy or bare aluminium alloy air sulphur hexafluoride SF i or nickel coated sulphur hexafluoride SF oll in coated air sulphur hexafluoride SF oll Source derived from IEC 6227 NOTE When engaging parts with different coatings or where one part is of bare material the permissible temperature and temperature rise shall be those of the surface material having the lowest permitted value 710 12280 00A Medium Voltage Application Guide Page 149 SWITCHGEAR The total coefficient factor K is derived from six individual factors K KI K2 K3 K4 K5 K6 e Kl is a function of the number of bars per phase and their shape The table below lists the value for KI according to the shape ratio for the busbar system e a and the number o
37. Codes The equipment s sensitivity and response for protection functions shall be programmable gt Overload 49 51 gt Undercurrent 37 Instantaneous Over current 50 Current Imbalance 46 Frequency 81 Auxiliary Trip A 86 97 Auxiliary Trip B 86 97 Excess start time 66 Maximum start Time 48 Starter Communications Failure 3 Battery Clock Failure 3 SCR Temperature Ground Fault 50G Overvoltage 59 Under voltage 27 Phase sequence 47 Phase Loss 47 Power Loss 32 VVVVV VV VV VV N NN WM v The following protection states are also provided e Motor not detected e Auxiliary trip A e Auxiliary trip B e Network communications e EEPROM failure e Gate drive failure e Conduction 1 invalid e Conduction 2 invalid e Conduction 3 invalid e Assembly control voltage low LOGIC CONTROL CONFIGURATION The equipment s possible responses to protection activation shall include at minimum e trip cease operation and disable the motor e warn notify the condition to the operator and continue operating e ride through write the event to memory 3 4 Programmable Relay Outputs The equipment shall provide output relays to control operation of e main contactor e bypass contactor e power factor correction capacitor bank The equipment shall provide an output relay to indicate that the unit is operating The equipment shall provide at least three additional relays with user selec
38. H Une DEE 8 44 Warranty and Repalr it eet e tec Ala a 8 4 5 Standards and Approvals sse 8 INTRODUCTION Introduction 1 1 Scope This document specifies the minimum requirements for a solid state reduced voltage motor starter for medium voltage application This specification is intended as a guideline for suppliers wishing to supply their product to customer name for their project name outline of requirement gt The solid state reduced voltage starter shall control three phases at V Hz and shall be rated to suit the application and motor characteristics Where possible motor and load curves will be provided and the supplier will use this data to justify selection The starter shall provide soft starting and soft stopping of the motor as required 1 2 Supplier Qualifications The equipment shall have been manufactured by a single vendor The manufacturer shall be certified under ISO9000 The manufacturer shall have produced solid state reduced voltage starters for a minimum of 20 years ENVIRONMENTAL SPECIFICATIONS Environmental Specifications 2 1 Environmental Specifications The equipment shall be suitable for storage at temperatures from 25 C to 55 C The equipment shall be suitable for use at temperatures from 10 C to 60 C The equipment shall be suitable for use at temperatures up to 40 C without derating The equipment shall be suitable for operation
39. I Peak value of short circuit current kA NOTE daN dekanewton is equal to 10 newtons 710 12280 00A Medium Voltage Application Guide Page 81 SWITCHGEAR Resonant frequency z supply not withi z supply not withi Calculation requirements Busbar systems are subjected to so under short circuit fault conditions It is important to ensure the busbar system will function safely under all known conditions When checking the design the most important considerations are the nominal operating current expected fault current a installation To check the safe n the ranges 48 Hz to 52 Hz and 96 H n the ranges 58 Hz to 62 Hz and 116 ty of a busbar system zto 104 H Hz to 124 thermal and electrodynamic stresses under normal The busbar system must be checked for potential resonance under normal operating conditions and fault conditions This is done by calculating the natural resonant frequency of the system which must meet the following criteria e 50 e 60 Z Hz operating conditions but more t the point of installation average ambient temperature and the altitude of the e Check that the current rating of the busbar system Li exceeds the expected nominal current Main factors maximu affecting the busbar rating are busbar material and configuration ambient temperature and m permissible temperature rise e Check the maximum expected temperature rise of the busbar during
40. KI Q Control components mounted on the controller compartment door A Ll EC a Reset pushbutton D G Emergency stop pushbutton Controller L O START O STOP 13573 A Page 48 Medium Voltage Application Guide 710 12280 00A Typical MVX panel line up SOFT STARTERS Busbars isolated in separate compartment Internal separation compartments isolate bus work during LV service Interlocking racking system for VCBs etc AuCom keypad and analog digital metering options available Safe LV compartment access without need to de energise MV section Easy to manoeuvre and install via lifting eye bolts Modular design allows for single panels or line ups Arc fault resistant enclosure Lockable doors as standard Two step door locking prevents accidental access Hinged door panels no more lost or damaged panels Small footprint phase cassette Viewing window to inspect switchgear status without opening doors Overpressure flap Bushing Busbar system Fixed contact insulator Shutter Current transformer Earth switch Enclosure 9 Low voltage compartment 10 Circuit breaker compartment I Vacuum circuit breaker 12 Door lock 13 Door handle 4 Inspection window 5 Cable compartment co Joa wm a wl rm Medium Voltage Application Guide Page 49 SOFT STARTERS
41. M 50 60 Hz Rated lightning impulse withstand voltage U MVSxxxx V02 04 MVSxxxx V06 V07 Rated power frequency withstand voltage Ua DIN SOOO EE 11 5 kV ke EE 20 kV normal current I MVS0080 Vxx MVSO159 Vxx MVS0230 Vxx MVS032 Vxx MVS0500 Vxx MVS0600 Vxx Rated short time withstand current symmetrical RMS l Form Designation 5a tuam rd en Ee ini Bypassed semiconductor motor starter form Control Inputs Start iEerminals 23 2 T scettr ertet e abet p cette too 24 VDC 8 mA approx Stop Terminals C31 C32 24 VDC 8 mA approx Reset Terminals C41 C42 24 VDC 8 mA approx Rate el ale Ee elle 24 VDC 8 mA approx Input B Terminals C63 C64 senus 24 VDC 8 mA approx Motor Thermistor Terminals B4 B5 ceteris hacerte eed Trip point gt 2 4 kQ NOTE AN All control inputs are potential free Do not apply external voltage to these inputs Low Voltage Supply Rated Voltage 1410130 or 220 240 V p irsedussel M RI cmm 50 60 Hz Typical POWER CONSUMDION Aere EE 70 W continuous Outputs Pela VACDULOUES Let 10 A 250 VAC resistive Ee 6 A 250 VAC 15 pf 0 3 10 A 30 VDC resistive Outputs on interface PCB Klee lee EE y Open Bypass Contactor 23 24 y Open R n Outp t PRG E WE y Open Outputs on Controller TEE EE dee Normally Open Output Relay 51 NEE Changeove
42. Motor synchronous speed synchronous speed rpm mains supply frequency Hz number of stator pole pairs percentage slip speed synchronous speed rpm rotor speed rpm output power KW rotor shaft speed rpm rotor torque Nm Motor electrical input power input power kW P 4 3 x Vxl xcos motor line voltage kV motor line current A motor power factor Motor efficiency Where eff motor efficiency 76 P motor output power kW P motor input power kW Page 6 Medium Voltage Application Guide 710 12280 00A MOOLS A slip ring induction motor is also referred to as a wound rotor motor In principle the stator construction is the same as that of a squirrel cage induction motor The rotor is made up of a set of windings embedded in rotor slots and brought out to a set of slip rings External rotor resistance is then connected to the slip rings via a brush gear arrangement The external rotor resistance is variable and is used for starting the motor Slip ring motors Slip ring rotor arrangement Slip ring motor installation H Three phase supply Main contactor Slip ring motor BH Stator B Rotor RI First stage resistor bank Second stage resistor bank A high level of starting torque is produced by matching the rotor resistance with the rotor leakage reactance as the motor speed increases At standstill all the ava
43. Use 300 1 A Short time withstand rating lin Use 10 kA rating Primary circuit voltage U Use 2 kV rating Step 2 Select real output power Real output power typically gt VA for digital type protection relay Use 2 5 VA this allows 1 5 VA for cable burden etc Step 3 Calculate protection class 5PX The instantaneous trip current level of protection relay OCI is set to 15 x l Lapp 15x 262 3930 A primary current Note In most digital protection relays the trip current levels are set with respect to the secondary current In this case _ 3900 SEC 77300 13 1A 1 The instantaneous trip current level for the CT secondary is 13 1 A The trip current level should fall between 100 to 50 of the accuracy limit factor ALF Using an ALF of 10 5P10 the trip current level of 3930 A falls outside the range 100 to 50 ALF so a 5P10 protection class CT is not suitable 100 ALF 1 0x10x300 3000 A 50 ALF 0 5x10x300 1500A 1500 lt 39302 3000 A Using an ALF of 15 5P15 the trip current level of 3930 A falls within the range 100 to 50 ALF so a 5PI5 protection class CT is suitable 100 ALF 1 0x15x300 4500 A 50 ALF 0 5x15x300 2250 A 2250s 3930s 4500 A Use protection class 5P 5 Page 116 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Step Calculate transformer TXR2 nominal primary current In A Exercise 3 Protection CT2 for
44. all environments and applications Customisable Protection The MVS offers comprehensive protection to ensure safe operation of the motor and soft starter The protection characteristics can be customised extensively to match the exact requirements of the installation Advanced Thermal Modelling Intelligent thermal modelling allows the soft starter to predict whether the motor can successfully complete a start The MVS uses information from previous starts to calculate the motor s available thermal capacity and will only permit a start which is predicted to succeed Comprehensive Event and Trip Logging The MVS has a 99 place event log to record information on soft starter operation A separate trip log stores detailed information about the last eight trips Informative Feedback Screens A digital display screen allows the MVS to display important information clearly Comprehensive metering information details of starter status and last start performance allow easy monitoring of the starter s performance at all times Dual Parameter Set he MVS can be programmed with two separate sets of operating parameters This allows the soft starter to control the motor in two different starting and stopping configurations The secondary motor settings are ideal for conventional squirrel cage motors which may start in two different conditions such as loaded and unloaded conveyors NOTE MVS soft starters are not suitable for
45. amount of braking torque is available to help slow the load and additional braking torque can be obtained by adding a braking circuit With 4 quadrants rectifiers active front end the VFD is able to brake the load by applying a reverse torque and returning the energy to the network The precise speed control available from a VFD is useful for avoiding water hammering in pipe systems or for gently starting and stopping conveyor belts carrying fragile material VFD motor running The ability to control motor speed is a big advantage if there is a need for speed regulation during continuous running Ifthe application only requires an extended starting and or stopping time a VFD may be more expensive than necessary Running at low speeds for long periods even with rated torque risks overheating the motor If extended low speed high torque operation is required an external fan is usually needed The manufacturer of the motor and or the VFD should specify the cooling requirements for this mode of operation VFD bypassed In some medium voltage motor applications a VFD is used to start the motor but is bypassed by a contactor or circuit breaker when running at mains supply frequency This means e motor start current never exceeds the motor full load current This is very useful on sites where the mains supply capacity is limited e the overall motor control system is more reliable because the VFD is only required durin
46. an inspection window Low Voltage Compartment The low voltage compartment provides safe isolation from any medium voltage equipment This is used for installation of low voltage control equipment including DIN rail mounted terminal blocks Equipment can be panel mounted on the LV compartment door for customer interfacing Page 70 Medium Voltage Application Guide 710 12280 00A IEC Switchgear Classification IEC 62271 200 classifies metal enclosed switchgear based on e compartment types e method of access to compartments e safety levels provided during access SWITCHGEAR effect on continuation of service during access type of insulation barriers between compartments internal arc endurance refer to section on internal arc classification The manufacturer must state which areas of the switchgear are accessible and provide a clearly defined switchgear classification Classification related to personnel safety in case of internal arc Types of compartments with regard to accessibility Features ocked based accessi ble Operator accessible compartment pa ed pa tended to rtment ure based rtment be opened ion and maintenance for normal accessible No tools for opening Interlocking al owing access only when HV parts are dead and earthed N o tools for opening Provision for ded to be opened for normal ration and maintenance based accessible compartment
47. are especially expensive if high start frequency is required e They cannot accommodate changing load conditions eg loaded or unloaded starts e They cannot provide soft stop Page 14 Medium Voltage Application Guide 710 12280 00A MIO en Star Delta starting Star delta starters are the most common reduced voltage starter used in industry because of their low cost The motor is initially connected in star configuration then after a preset time the motor is disconnected from the supply and reconnected in delta configuration The current and torque in the star configuration are one third of the full voltage current and torque when the motor is connected in delta Star delta starter installation LEE B Thermal overload Motor three phase 4 Delta contactor LE 09456 A The star and delta configurations provide fixed levels of current and torque and cannot be adjusted to suit the application e Ifthe star configuration does not provide enough torque to accelerate the load to full speed a high starting torque motor such as a double cage motor should be employed fthe motor does not reach full speed in star the transition to delta configuration will result in a high current and torque step defeating the purpose of reduced voltage starting Most star delta starters are open transition starters so the transition from star to delta results in very high current and torque transients in addition to the high step
48. conditions and pumps which require very low torque at low speed This method also suits motors running on generator supplies as the starting load is gradually applied to the generator set This provides stable voltage and frequency control of the generator set during motor starting Constant acceleration soft start Constant acceleration or linear acceleration starters monitor the motor speed by means of a tacho generator attached to the motor shaft The voltage applied to the motor is controlled to deliver a constant rate of acceleration over a selected acceleration time A current limiting circuit can also be used to limit the maximum starting current particularly in applications where a potential exists for jammed loads f 1 Full voltage start current L200 aa 2 Current limit E e i 3 Full voltage start torque 2 p pu 4 Torque output at current limit 5 10 O 5 Acceleration torque o S D Load torque curve e T T T T I T T T T 1 5 E 10 20 30 40 50 60 70 80 90 100 8 Speed full speed 710 12280 00A Medium Voltage Application Guide Page 21 SOFT STARTERS 3 2 Benefits Electrical Benefits e Minimise start current levels to match application requirements This reduces overall demand on the electrical supply e Eliminate current transients during motor starting and stopping This avoids supply voltage dips which can affect the performance of o
49. controlling two separate motors The secondary parameter set should only be used for a secondary configuration of the primary motor he MVS will use the secondary motor settings to control a start when instructed via a programmable input Fibre Optics The MVS uses two line fibre optic connections between the low voltage control module and the high voltage power assembly for electrical isolation This fibre optic link simplifies installation of chassis mount MVS starters into custom panels MVS Power Assembly The MVS power assembly is a very robust and compact design minimising panel space requirements The unique draw out design simplifies general maintenance and servicing MVS power assembly Phase arms extend via built in runner including balance resistors snubbers and gate drive 2 Small footprint and depth saves space Conformal coating on all PCBs for protection in environments up to Pollution Degree 3 Current measured on all three phases Bypass terminals retain motor protection e Convenient earth points L7 Mounted inside frame to ensure sufficient Hr e D Compact modular design as a single unit Page 30 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS General Technical Data Supply Mains Voltage MVSxxxx VO2 2 3 kV Phase phase MVSxxxx V03 3 3 kV Phase phase MVSxxxx V04 4 2 kV Phase phase MVSxxxx V06 6 6 kV Phase phase MVSxxxx VO7 7 2 kV Phase phase Rated regun
50. current lan expected if a short circuit fault occurred at the point of installation NOTE IN Switchgear peak withstand current rating is commonly referred to as rated short circuit making capacity Peak withstand current By cere B 2z25xlk wi FV die f 50 Hz V2 x Ik S g TIER 42 e 3 o z bk 45 ms Time ms Short time withstand current Ik kA This is the level of symmetrical rms fault current the switchgear can carry in the closed position for a short time period typically second without temperature rise exceeding predefined levels IEC 62271 1 specifies standard ratings as base 10 multiples of 1 25 1 6 2 2 5 3 15 4 5 6 3 8 Short time withstand duration tk seconds This is the period of time that the equipment is rated to carry the short time withstand current IEC 62271 1 specifies a standard rating of second although durations of 0 5 2 and 3 seconds are allowed Frequency fr Hz This is the rated test frequency of the switchgear and must match the operating frequency of the installation Two medium voltage mains supply frequencies are used globally e 50 Hz in European systems e 60 Hz in American systems 710 12280 00A Medium Voltage Application Guide Page 169 SWITCHGEAR 4 10 Prote ction index IP Ratings IEC 60529 specifies levels of protection again composed of up to four elemen
51. current produces a magnetic field in each rotor bar Interaction between the stator s rotating magnetic field and the rotor bar magnetic fields produces a torque which causes the rotor to be driven in the same rotational direction as the stator magnetic field Torque produced by the rotor varies from stationary to full running speed This torque is primarily a function of the rotor resistance and leakage reactance The latter is determined by the difference in rotational speed between stator 710 12280 00A Medium Voltage Application Guide Page 5 MOORS magnetic field and the rotor otherwise known as slip Slip is commonly expressed as a percentage of the motor s synchronous speed Motor start performance characteristics can vary greatly depending on rotor design and construction but in general a motor with high locked rotor current will produce low locked rotor torque and vice versa A high resistance rotor produces relatively high starting torque but runs at high slip which causes inefficiency To produce superior starting and running characteristics specially shaped rotor bars or double cage rotors are used Typical start performance characteristics ofan induction motor aJ Full voltage motor current 7xFLC 2 Full voltage motor torque 6 x FLC Load torque quadratic load eg 5x FLC pump 4x FLC Current 3 x FLC 2x FLC 1x FLC 10 20 30 40 50 60 70 80 90 100 Speed Useful formulae
52. e rated short time withstand current I e duration of short time withstand t e rated peak withstand current typically 2 5 at 50 Hz I e protection degree for enclosure and apparatus Operating device specifics e types of operating devices e rated auxiliary supply voltage if any e rated auxiliary supply frequency if any e rated gas pressure if any e special interlocking requirements Switchgear derating Switchgear must be derated for altitudes exceeding 000 metres and ambient temperatures exceeding 40 C Insulation derating according to altitude The relevant standards specify the derating required for equipment installed at an altitude greater than 1000 metres SM v Guideline derate by 1 2576 U peak per 100 metres above 1000 metres B This applies for lightning impulse withstand voltage and for power frequency withstand voltage 50 Hz minute Derating for altitude only applies to air insulated switchgear not vacuum or SF6 insulated equipment Current derating IEC 62271 1 defines the maximum permissible temperature rise for each device material and dielectric medium using a reference ambient temperature of 40 C The actual temperature rise is affected by e the rated current e the ambient temperature e the cubicle type and its protection index IP rating Guideline derate by 126 per degree above 40 C Current derating coefficient AMA t 0 9 be
53. equivalent inductance of banks which are switched in L The equivalent inductance is 13 3 uH Step 5 Calculate the peak inrush current is 2 Cr 1 3 eve 1G E 6300 x x 2 99x 165 R 3 554165 1 40 eg 2 9075 1 6300 x 8 220 saa 6300 x 0 67 x 41 25 x 1 s 6300 x 40 67 x 41 25 x 0 019 6300 x 40 52 45483A The peak inrush current is 4543 A To be suitable the peak inrush current I must be less than 100 times the capacitor s nominal current 100 x Irom jos ea nom BAU _ _ 689 48x 6 3 689 10 91 63 15A In this example 4543 100 x 63 15 A This installation is acceptable NOTE When selecting line fuses for upstream protection the fuse pre melt figure must be greater than the capacitor bank s peak inrush current If using a circuit breaker for upstream protection the circuit breaker s making capacity at rated voltage must be at least equal to the capacitor bank s peak inrush current Page 142 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR 4 5 Calculations Transformer Calculations Rated secondary current l A transformer s rated secondary current I is the maximum current it can supply before the output terminal voltage starts to drop below its rated voltage U The rated secondary current can be calculated using the following formula assuming the applied p
54. isolated position The interlocking mechanisms shall be provided to satisfy the following requirements ELECTRICAL SUPPLY 3 7 3 8 3 9 3 10 3 11 9 Circuit breaker truck shall only be movable from engaged position to isolated position and vice versa only when the circuit breaker is open 10 Circuit breaker truck shall be locked in cubicle panel while the circuit breaker remains closed 11 Circuit breaker cannot be closed unless the circuit breaker truck is in the fully engaged position Shutters 1 During the isolation of the circuit breaker the busbars and cable orifices shall be automatically covered by self closing shutters The shutters for the busbar and cable orifices shall be independent of each other so that one can be opened manually without interfering with the other Provision shall also be provided for padlocking the shutters All busbars or cable orifices shall have prominent markings or labelling to clearly identify them The safety shutters shall be metallic type and shall be earthed Earthing amp Earth Switch 1 2 All metal parts shall be earthed in an approved manner to the earthing system The necessary terminals on each part of the equipment shall be provided An integral earthing device shall be provided to connect each outgoing cables of each outgoing circuit breaker to earth when required without the use of loose attachments It shall be possible to switch the device on
55. kVAr NOTE AN The capacitor bank nominal voltage rating is typically 1 2 times the system voltage to protect against transient and harmonic voltages The capacitor bank power must be re rated after selection 710 12280 00A Medium Voltage Application Guide Page 139 SWITCHGEAR Calculations peak inrush current of a fixed capacitor bank To calculate the peak inrush current l of a fixed capacitor bank with no extra inrush reactance Strans 5000 kVA Z 5 U 6 3 kV ber lp Q 250 kVAr 13812 A Step Calculate capacitor bank nominal current laom Q capacitor bank power kVAr U system voltage kV a m Bai 250 The capacitor bank s nominal current is 23 A Step 2 Calculate the short circuit power of the system S Stans transformer nominal power rating kVA Z transformer impedance 76 Sco 2 x 100 9000 100 100000 kVA The system short circuit power is 100 000 kVA Step 3 Calculate the peak inrush current lom Capacitor bank nominal current A S transformer short circuit power kVA Q capacitor bank power kVA z Se m 2X laom bg c2 d 100000 4 2 x 23x v2 250 4 2 x 23x 400 2 x 23x 20 650 54 A The peak inrush current is 650 A To be suitable the peak inrush current I must be less than 100 times the capacitor s nominal current I I 100 x I p In this example 650 100 x 23 A Th
56. low voltage motor lt 500 VAC Feature List Starting Comprehensive feedback e Constant current e Starter status LE Ds e Current ramp e Date and time stamped event logging Stopping e Operational counters starts hours run kWh e Coast to stop e Performance monitoring current voltage power e Soft stop factor kWh Protection e User programmable monitoring screen e Under Overvoltage e Multi level password protection e Mains frequency e Emergency stop push button e Phase sequence Power Connection e Shorted SCR e 50Ato 600 A nominal e Motor overload thermal model e 2300 VAC to 7200 VAC e Instantaneous overcurrent two stages Accessories optional e Tlime overcurrent e DeviceNet Modbus or Profibus communication interfaces e Synchronous motor control e PCSoftware e Overvoltage protection e Control supply transformer e MV LV Control transformer e Ground fault e Undercurrent e Current imbalance e Motor thermistor e Excess start time e Power circuit e Auxiliary trip Extensive input and output options e Remote control inputs 3 x fixed 2 x programmable e Relay outputs 3 x fixed 3 x programmable e Analog output x programmable e Serial port with module 710 12280 00A Medium Voltage Application Guide Page 29 SOFT STARTERS Key Features MVS soft starters offer several special functions to ensure ease of use and to provide optimal motor control in
57. magnitudes Closed transition star delta starters are rarely used due to the increased complexity and cost The closed transition starter reduces the reclose effect but does not improve the controllability of the start parameters Start performance characteristics of a star delta starter 7xFLC a 6xFLC Full voltage start current r delta start current Full voltage torque 5xFLC 4xFLC D Current and torque transient Current Torque 10 20 30 40 50 60 70 80 90 100 Speed How does soft start compare with star delta starting Compared with star delta starters soft starters are much more flexible and provide a smooth start with no risk of transients Star delta starters offer limited performance because Start torque cannot be adjusted to accommodate motor and load characteristics e There is an open transition between star and delta connection that results in damaging torque and current transients e They cannot accommodate varying load conditions eg loaded or unloaded starts e They cannot provide soft stop The main advantages of star delta starters are e They may be cheaper than a soft starter e When used to start an extremely light load they may limit the start current to a lower level than a soft starter However severe current and torque transients may still occur 710 12280 00A Medium Voltage Application Guide Page 15 MOORS Soft starters Ele
58. metal enclosed switchgear arc withstand EC International Electrotechnical Commission EEE Institute of Electrical and Electronics Engineers Nominal current A asym la Asymmetrical fault current kA rms sm l Symmetrical fault current kA rms ne Rated back to back capacitor breaking current A b Rated back to back capacitor inrush making current kA e Rated cable charging breaking current A d Rated out of phase breaking current kA S Rated single capacitor bank breaking current A i Short time withstand current kA Rated current A p lan Peak let through fault current of an installation KA peak lt Short circuit rms current of an installation kA STP Stopping current emp Starting current FP Incomer feeder panel o Zero sequence current Positive sequence current 2 Negative sequence current VA Apparent power unit VAr Reactive power unit 710 12280 00A Medium Voltage Application Guide Page 219 RESOURCES kW LRC LRT LSC MTP MV NEMA OSI pf PFC PFP rms SF6 SC SCO SST Active power unit Locked rotor current A Locked rotor torque Nm Loss of service continuity metal enclosed switchgear classification Metering panel Medium voltage National Electrical Manufacturers Association Open systems interconnection Active power VV Power factor Power factor correction Power factor panel Root mean squared Reactive power VAr Sulphur hexafluoride Apparent power VA Short c
59. motor is a large portion of the load It is recommended that the transformer output voltage should not drop more than 0 of its nominal value when using a soft starter to start a motor Lo d or Drei 8 Where o ax U L rated secondary current A S transformer power kVA E U es U rated secondary voltage kV 100 2 E transformer internally generated EMF kV Z int EU 1000 Z percentage impedance I Z int transformer internal impedance Q HoadxZ int U int internal voltage drop kV U int 000 l load load current A LL secondary output voltage due to overload kV U E Urint Example Transformer power S 30 MVA Secondary rated voltage U 6 6 kV Impedance Z 10 Assume infinite power system Rated secondary current 208 i 43x U 30000 i 3 x 6 6 30000 1143 2624 32 A The rated secondary current is 2625 A Transformer internally generated EMF E e aa 100 Z 100 AX 100 10 6 6 x 90 6 6x1 11 7 33 kV The internally generated EMF is 7 33 KV 710 12280 00A Medium Voltage Application Guide Page 145 SWITCHGEAR Transformer internal impedance Z int Z int x 1000 r _ 1 33 6 6 2625 2 73 4600 2625 0 280 The internal impedance is 0 28 x1000 Exercise Calculate the transformer s output terminal voltage drop if the load was drawing
60. o2 L ol3 L QOVXeN H Mains supply RH Busbar system OI Forward direction circuit breaker Reverse direction circuit breaker Qio Main circuit breaker for SST Bypass circuit breaker for SST Earth switch motor side Earth switch supply side 710 12280 00A Medium Voltage Application Guide Page 59 SOFT STARTERS Operating Sequence NOTE The phase sequence of the incoming mains supply and the motor winding connections must be NOTE The motor must be stopped before changing its operating direction There is always a short time delay built into the selected changeover of the phase rotation This is typically less than 3 seconds which is enough time to allow motor flux and thus any back EMF in the motor to decay The soft starter SST can use the coast to stop or soft stop method A verified for correct motor rotation Forward control sequence Before starting both the supply side earth switch O3 and the motor side earth switch Q30 must be open and mains supply must be present 25 3 4 The forward direction circuit breaker QI is closed Electrical interlocking disables the reverse direction circuit breaker Q2 from closing The soft starter is given a start command and the main circuit breaker O10 closes The soft starter performs a series of prestart checks then starts the motor in the forward direction Once the motor has reached ful
61. part of normal operation eg conveyors b The electric VO ro Commissio ro su al principle is very sim electrically interlocked switching devices connected in paralle the mains supply while the output of the other switching device is anti phase w tage installations these switching devices are normally draw out circuit breakers or fused contactors Once the mains supply phase sequence has been preselected the moto tational direction also referred to as positive or negative motor direction all and hammer mil The output of on r is started and will to change the mechanical direction s shredders and cutting machines ple The phase sequence direction of the mains supply is preselected using two e switching device is in phase with ith the mains supply In medium run in either the forward or reverse ning of such applications is normally carried out with the motor initially uncoupled from the load If motor tation during commissioning is opposite to what is expected this is rectified by exchanging any two incoming pply phases or any two output motor phases of the switchgear arrangement Typical AuCom medium voltage switchgear arrangement for a single forward reverse motor starting system LO kV 13 8 kV with MVX soft starter For clarity current transformers and motor protection relays are not shown ve E E SST Lb T1
62. short and straight as possible and any joints shall not increase the resistance of the connection When dissimilar metals are connected approved means shall be provided to prevent electro chemical corrosion The busbars and connections shall be so arranged and supported that under no circumstances including short circuit conditions can the clearances from earthed metalwork or other conductors be less than the distances required in the standards 3 6 Circuit Breakers 1 2 3 OND CB s shall be Vacuum type for new MV Switchboards CB s must comply with IEC 62271 100 The CB breaking capacity shall be equal to or greater than the busbar Isc The circuit breaker shall be of the trip free vertical or horizontal isolation horizontal drawout carriage mounted type The number of electrical and mechanical operations must be stated The various parts of the circuit breaker shall be of substantial construction carefully fitted to reduce mechanical shock during operation to a minimum and to prevent inadvertent operation due to vibration or other causes The circuit breaker shall be arranged for trip free independent manual operation The CB method of operation to be provided as part of the submission The circuit breakers shall have been subjected to impulse voltage tests for the rated voltage The circuit breaker shall be provided with automatic locking devices to lock the movable portion of the unit in either the engaged or fully
63. switchgear and controlgear for rated voltages above kV and up to and including 52 kV to be used in severe climatic conditions voltage switchgear and controlgear Capacitive current switching capability ir insulated disconnectors for rated voltages above 52 kV voltage switchgear and controlgear Electrical endurance testing for circuit breakers above a rated voltage of 52 kV NOTE Edition dates have been deliberately omitted from the IEC Standard Number When referring to a standard always ensure you are using the latest edition gt Page 166 Medium Voltage Application Guide 710 12280 00A 4 8 Comparison of IEC and IEEE Standards SWITCHGEAR Although the IEC International Electrotechnical Commission is the main international organisation publishing international standards relating to medium voltage switchgear the Institute of Electrical and Electronics Engineers IEEE and the American National Standards Institute ANSI also publish standards AU SS IEC and IEEE have a cooperation agreement and some standards are jointly developed ANSI is the US representative to IEC In some cases th include requirements not present in another standard LN NOTE e requirements of similar standards from different organisations may conflict or one standard may If equipment must comply with more than one standard the requirements of each standard should be indi
64. the insulation medium may be degraded or the contact separation distance may need adjusting For 3 phase circuits TRV refers to the voltage that will appear across the first pole to open The ratio of TRV to single phase voltage is referred to as the first pole to clear factor and is 1 5 for systems up to 72 5 kV Rated TRV U for circuit breakers intended for use on cable systems Class S1 IEC 62271 100 defines standard TRV peak voltage ratings TRV withstand ratings for short circuit breaking current an Uc Y Source IEC 62271 100 Where U TRV peak voltage value kV U rated voltage kV U 1715 x U 3 r Voltage envelope for a two parameter TRV waveform on a cable system less than 100 kV 13722 A iy Time Source IEC 6227 1 100 Rated out of phase breaking current la kA When a circuit breaker opens with its input and output voltages out of phase larger than normal voltages will appear across the circuit breaker poles This condition reduces the circuit breaker s maximum breaking current capability TRV withstand ratings for out of phase current I U ej Une 2 i x 4 62 995 Source IEC 62271 100 Where U TRV peak voltage value kV U rated voltage kV U 2551 x U Medium Voltage Application Guide 710 12280 00A SWITCHGEAR EC 62271 100 recommends capacitive switching current rat
65. the soft starter and must be integrated into the entire system This control method becomes complex and expensive and in most cases an upgrade will involve a complete replacement of the synchronous motor for a standard squirrel cage induction motor 710 12280 00A Medium Voltage Application Guide Page 67 SOFT STARTERS 3 8 Common standards for MV soft starters and switchgear panels MV soft starters and switchgear panels are commonly designed to meet the following international standards NOTE IN This information is an overview of the most common conformance standards used in the medium voltage industry For specific equipment conformance always refer to the technical data supplied by the manufacturer Switchgear and apparatus High Voltage switchgear amp control gear Part Common IEC62271 1 Specifications High Voltage switchgear amp control gear Part 200 AC metal IEC6227 200 enclosed switchgear and control gear for rated voltages from kV to 52 kV igh voltage switchgear and controlgear Part 304 Design IEC62271 304 classes for indoor enclosed switchgear and controlgear for rated voltages above kV up to and including 52 kV to be used in severe climatic conditions AC Metal enclosed Switchgear and Control Equipment for rated voltage from kV to 52 kV Chinese standard General Technology Requirements of High voltage DL T 593 Switchgear and Control Equipment Chinese standard EEE St
66. the voltage to the motor in order to control the monitored parameters Closed loop controller eeng M 4 Current transformer feedback Common closed loop systems are 13474 A e Constant Current or Current Limit e Tlimed Current Ramp e Constant Acceleration Constant current soft start Constant current starters monitor the starting current Increasing or decreasing the output voltage increases or decreases the current supplied to the motor As the motor accelerates the stator impedance rises and in order to maintain a constant current the voltage also rises The exact relationship between voltage and speed depends on the motor design With a constant current starter full torque is available as the motor reaches full speed It is important that the starting current is high enough to accelerate the motor to full speed under all conditions If the torque is insufficient for acceleration at any time during the start the motor will continue to run at the reduced speed This will overheat the motor unless there is excess start time protection Timed current ramp soft start Timed current ramp soft starters increase the current from a selected start level to the maximum start current at a controlled rate This caters for variation in starting torque requirements or can deliver reduced starting torque without limiting the maximum starting torque Typical applications are conveyors which start under varying load
67. to an internal file There shall be two files available The equipment shall permit the operator to reload a previously saved configuration set from an internal file There shall be two files available The equipment shall permit the operator to restore default settings The equipment shall support remote management via a control network with a choice of Modbus Profibus and DeviceNet as a minimum The equipment shall provide an on board real time clock but failure of this clock due to low battery shall not trip the starter LOGIC CONTROL CONFIGURATION 3 2 Operating Configurations The equipment shall permit the user to select between multiple profiles for starting the motor The equipment shall provide a kick start option for starting the motor The equipment shall permit the user to select between multiple profiles for stopping the motor The equipment shall provide a feedback ramp option for stopping the motor The equipment shall provide a means of automatically stopping the motor at a predetermined time or after a predetermined period of operation The equipment shall be suitable for use with dual speed and slip ring motors Thermal modeling that allows the soft starter to dynamically calculate the motor temperature predict the motors available thermal capacity to predict whether the motor can successfully complete a start 3 3 Motor and System Protection Features The starter shall have the followi
68. top exit arc flaps for pressure release Bus Coupler Panel BCP Typical Bus Coupler Panel lee Front view Side view 11166 A Rear view EE Circuit breaker Current transformer set Earth switch Page 76 Medium Voltage Application Guide 710 12280 00A Bus Riser Panel BRP A bus riser panel contains a vertical 3 phase bus which connects the output of a bus coupler panel at the bottom of the enclosure to a horizontal busbar system at the top of the enclosure In order to physically connect two adjacent horizontal busbar systems together a bus riser panel must be used alongside a bus coupler panel Voltage transformers along with low voltage equipment can be supplied as optional extras AuCom provides a Bus Riser Panel as part of its L Series switchgear range This is rated at 12 kV from 630 A to 2000 A An IAC classification of 31 5 kA for second is achieved by double skin compartments special locking door designs and top exit arc flaps for pressure release Typical Bus Riser Panel 11170 A Front view Side view Rear view Voltage transformer fused and withdrawable 710 12280 00A Medium Voltage Application Guide Page 77 SWITCHGEAR Metering Panel MTP A metering panel contains a primary h
69. uc O o E z E x 0 1 s71 8x 2xlk x 0 01 0 1 1 10 Jp 100 Prospective current kA rms Source example curves based on ABB CEF fuse links Example If the prospective rms fault current was 5 kA the peak let through current would be approximately 2 kA without afuse Ifa 50 A fuse was installed the rms fault current would be limited to 1 5 kA and the peak let through current would be 3 8 kA downstream of the fuse Pr data Fuse data sheets provide two lt figures e minimum l t is the amount of let through energy required to start a fuse melt and create an arc e maximum l t is the total amount of let through energy required to extinguish an arc and completely rupture open circuit a fuse This data is important for fuse discrimination The maximum It of the downstream fuse must be less than the minimum Ft of the upstream fuse If a fuse is selected to protect a cable the maximum lt of the fuse must be greater than the A S thermal rating of the cable Ratings Irrespective of which standard a fuse has been type tested too the following generic ratings usually apply Different standards require different rating information to be published on the fuse nameplate 710 12280 00A Medium Voltage Application Guide Page 105 SWITCHGEAR Nominal current In A This is the maximum continuous current a fuse can sustain without risk of rupturing It takes into account the method of installation and the exp
70. when shorting out the rotor resistance A second voltage ramp with constant current control is provided for acceleration to full running speed Typical slip ring motor starting system using a soft starter for control K1 ji 13531 A Mains supply Rotor resistance single stage Main contactor Bypass contactor Slip ring wound rotor motor Rotor resistance contactor Operating sequence NOTE The rotor resistance must be engineered to provide the necessary acceleration torque during motor starting This example assumes a soft starter which offers a dedicated slip ring motor control function eg AuCom MVS or MVX Starting control sequence The soft starter SST is given a start command and main contactor KI closes 2 The soft starter performs a series of prestart checks then ramps up to full voltage using Ramp 3 Oncethe rotor has reached a constant speed the voltage on the output ofthe soft starter SST is backed off and rotor resistance contactor K3 closes shorting out rotor resistance RI 4 The output of the soft starter SST is ramped up to full voltage using Ramp 2 accelerating the motor to full speed 5 Bypass contactor K2 closes and the starting sequence is complete Page 66 Medium Voltage Application Guide 710 12280 00A AuCom slip ring motor control sub states ME t2 SOFT STARTERS Q S1 s2 3 S4 g E Wb E P2 P3
71. will be selected and remain as the supply as long as it is healthy If both power sources are lost both sources NI and N2 are isolated from the receiving network DB MANUAL mode Select NI or N2 as the power source 710 12280 00A Medium Voltage Application Guide Page 175 SCHEMATIC DIAGRAMS Ir K1 K3 DB AUTO mode z 14045 A is the prioritised power source and if healthy will always supply the receiving network DB If power source is lost the controller commands the standby generator to start Once the generator is at correct voltage and equency power source G is switched in to supply the receiving network DB The controller switches back to once it has been re established MANUAL mode Select NI or G as the power source N1I N2 N3 N1 N2 N3 Ki K2 K3 14046 A DB AUTO mode with line priority NI is the prioritised power source and if healthy will always supply the receiving network DB If NI is lost the controller switches over to power source N2 If power source N2 is lost the controller switches over to power source N3 The controller switches back to INI once it has been re established AUTO mode without line priority The first power source verified as healthy will supply the receiving network DB If this power source is lost the next healthy power source is selected and will remain as the supply as long as it is healthy The order of power source
72. wiring or small power circuits For other control circuits the minimum size shall be 1 0 mm sq Wiring shall be neatly run and shall be securely fixed in insulated ducting or harnesses with easy access for checking A suitable control wiring colour schedule shall be provided to differentiate voltages and functions RESOURCES 6 2 Metric Imperial Conversion Factors Length mile 1 609 km km 0 621 mile yd 0914m m 1 09 yd ft 0 305 m m 3 28 ft in 254mm mm 0 039 in Mass OZ 283g g 0 0352 oz b 0454 kg kg 2 20 b Area in 645 cm cm 0 155 in ft 0093m m 108 ft Volume in 64cnv cm 0 061 in i 0 028 m m 353f pint 0 568 J6 pint gallon imperial 4 551 0220 gallon gallon US 379 0264 gallon Velocity mile h 6l km h km h 0 622 mile h knot 1 85 km h km h 0 540 knot Power hp 0 746 kw kW 34hp kcal h 16W W 0 860 kcal h Energy cal 4187 0239 cal kWh 36M MJ 0278 kWh Force bf 445N N 0 225 Ibf kgf 9807N N 0 102 kgf Moment of Inertia ft Ib 0413 Nm Nm 2 42 ft 1b ft 1p 4 054 kgm kgm 0 247 ft 1b Temperature freezing point 32 F 0 C boiling point 2129F 100 C typical ambient 04 F 40 C e to convert a temperature from Fahrenheit to degrees Celsius C t F 32 x 0 556 e to convert a temperature from degrees Celsius to Fahrenheit F t C x 1 8 32 For a
73. with a 5 A secondary rating are becoming less common as more CT driven equipment becomes digital For long secondary cable runs CTs with A secondary windings can minimise the transformer and secondary cable size Transformer ratio Kn This is the ratio of secondary to primary winding turns z K n ler Ny N Rated thermal short time withstand current l n kA This is the highest level of rms primary fault current which the CT can endure both thermally and dynamically for second without damage When used in a medium voltage enclosure the ly rating should match the short time withstand rating of the entire switchgear Page 10 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR This is the ratio of a CT s short time withstand current rating to its primary current rating Overcurrent coefficient Ksi ks lh This coefficient indicates how difficult it would be to manufacture a CT A higher coefficient means a physically larger CT which is more difficult to manufacture K lt 100 easy to manufacture K 100 500 difficult to manufacture with certain limitations K gt 500 extremely difficult to manufacture Rated primary circuit voltage Up kV The primary circuit voltage rating indicates the level on insulation provided by the CT If a ring type CT is installed around a cable or bushing the insulation level can be provided by the cable or bushing Rated primary vo
74. x0 091 x8 9 _ 1307 39 207 33 6 31 C Asc The short circuit temperature rise is 6 3 C The maximum allowable continuous temperature of the busbar system is 90 C The potential total temperature after short circuit is 96 3 C Insulator stand offs and all other items in physical contact with the busbar must be able to withstand this temperature Page 152 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Electrodynamic withstand Electrodynamic forces Busbars parallel Support F1 e Non E Ga h 2 tere F b Cru qui H CT i 3 Id Distance between phases cm Distance between insulators on a single phase cm Force on busbar centre of gravity daN IL Peak value of short circuit current kA NOTE daN dekanewton is equal to 10 newtons Insulator height h Distance from head of insulator to busbar centre of gravity Force on head of insulator stand off daN Forces on parallel busbars Maximum forces between parallel busbars occur as a result of the peak asymmetrical fault current 1 The maximum peak fault current can be calculated from the busbar system s short time withstand rating l Values for a system with 45 ms DC time constant SsemWeueny Hg amp When short circuit current flows in a busbar the electrodynamic force exerted on a parallel busbar is l Where F 2 xox x10
75. 0 8 07 Uo Es 0 6 S S 05 ES 0 1000 2000 3000 4000 5000 Altitude m 710 12280 00A Medium Voltage Application Guide Page 73 SWITCHGEAR 4 2 Standard Enclosure Configurations Incomer Feeder Panel IFP As the name implies this panel configuration serves two purposes e Asanincomer panel This switches the incoming main supply onto the common horizontal busbar system of a metal enclosed switchgear arrangement e Asa feeder panel This switches the main supply from the common horizontal busbar system of a metal enclosed switchgear arrangement onto a specific feeder circuit The enclosure will always have a main circuit breaker normally withdrawable housed in its own compartment of the panel An earth switch at the cable termination end of the circuit provides isolation during shutdown and maintenance Interlocking ensures that the earth switch cannot be closed until the main circuit breaker is open and racked out into the test position Current transformers are fitted to interface with a protection relay for circuit breaker trip operation Depending on the required function voltage transformers can be supplied These can be 3 phase or single phase either fixed or withdrawable style A variety of low voltage equipment is used which is mounted in its own segregated compartment situated at the top front of the enclosure assembly v AuCom provides an Incomer Feeder Panel as part of its L Series switchgear ran
76. 1 _ 11 1 18 9 34 kA 43 x 0 72 J3 x0 68 7 2 5x0 525 21 312 kA 21312 A 2 5x8 82 22 05 kA 2 5x9 34 23 35 kA 710 12280 00A Medium Voltage Application Guide Page 161 SWITCHGEAR 4 6 Switchgear Inspection Checklists These checklists outline the typical minimum electro mechanical inspections for a new switchgear installation Mechanical Inspection Location Date nspection staff Cubicle serial number Passed Comments Y N Contract Eye bolts fitted Explosion vent flaps screws fitted holes taped Holes not used for arc duct filled with fixings LV doors cutouts LV doors opening and closing Cable compartment doors opening and closing lt CH Q 9 wW Q E O 0 O e d 9 O Kei bg 2 2 ca w 2 a o CO Si 2 ca Door locks king labe CB locking label Danger labels front and rear Cable compartment door unlocking label VCB compartment padlocking mechanism fitted and operating Shutter operation utter danger labels mmm gt gt od a rth switch interlock with VCB EE fo CH amp O Earth switch interlock with solenoid use N A if not fitted rth switch operation rth switch auxiliaries check alignment and O lo D oi et O 3 lt Q E Si o o ct g Q A vo
77. 1 qu 217 I am c2 7 8 I la v 2 Al Phase cassette LI L3 Input power terminals supply side 3 Phase 50 60 Hz Supply 2 Motor KI Main contactor fused withdrawable Q3 Earth switch K2 Bypass contactor fixed TI T3 Output power terminals motor side CT 1 3 Current transformers x3 A3 Power interface PCB Ul Metal oxide varistors MOVs 3 Current transformer inputs Power Circuit Configuration with Circuit Breakers MVX power circuit with main circuit breaker and bypass circuit breaker Q2 at C o es m J Q1 A1 I x We HB M n aa b T I L2 T2 T x e M Gg 2 M aum 2 m 13 M E Ge 2 I Ph Au i VA o zr I E L LU ELLE a gen i I m 22 8 a i Al Phase cassette 2 Motor 3 Phase 50 60 Hz Supply Q3 Earth switch QI Main circuit breaker withdrawable TI T3 Output power terminals motor side Q2 Bypass circuit breaker fixed A3 Power interface PCB CT 1 3 Current transformers x3 3 Current transformer inputs Ul Metal oxide varistors MOVs 4 Motor protection relay MPR LI L3 nput power terminals supply side Page 38 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Enclosures MVX soft starters can be installed easily into standard enclosures to provide a complete motor control cabinet
78. 2265 A gt 2000 A 710 12280 00A Medium Voltage Application Guide Page 151 SWITCHGEAR Short time withstand current ln A The temperature rise during a short circuit needs to be calculated assuming the current flows for the busbar s entire rated short circuit duration t The total busbar temperature Oy is the calculated temperature rise during a short circuit period A added to the maximum allowable temperature of the busbar 0 0 AO 0 Short circuit temperature rise is calculated as Where A0 temperature rise during a short circuit C p20 resistivity at 20 C copper 1 83 uQ cm aluminium 2 90 uQ cm lh short time withstand current kA L short time withstand duration s 0 0 24 x p20 x ly xt n number of busbars per phase nxSjxex8 S busbar cross section cm C specific heat C copper 0 091 kcal kg C aluminium 0 23 kcal kg C o density of metal copper 8 9 g cm aluminium 2 7 g cm 0 maximum allowable temperature of the busbar C bare copper 90 C Exercise A busbar system has two copper bars per phase with a short time withstand rating of 31 5 kA for 3 seconds Each busbar is 8 cm wide and cm deep Calculate the total temperature of the busbar after a short circuit 0 24xp20 xl xt nxS xcx8 0 24x1 83x31 5 x3 2x8 x0 091x8 9 0 24 x1 83 x992 25 x3 256
79. 27 SOFT STARTERS Local control and feedback e local keypad e emergency stop actuator e alphanumeric or graphical display e multi language interfacing e status LEDs e motor and starter monitoring data e metering data e event counters e data logging Communication options e signal level protocols eg ASi InterBus S e serial protocols eg DeviceNet Modbus RTU Profibus DP e Ethernet protocols eg EtherNet IP Modbus TCP ProfiNet e fibre optic linking provides superior EMC and LV MV isolation Special Functions e Internally bypassed when starter is in run state e Dynamic braking e Slow speed forward and reverse operation ie jogging e Auto reset and restart on selected trip types e Auto start and stop timer or clock e Slip ring wound rotor motor control e Synchronous motor control e In line 3 wire or inside delta 6 wire motor connection What is an inside delta connection Inside delta connection also called six wire connection places the soft starter SCRs in series with each motor winding This means that the soft starter carries only phase current not line current This allows the soft starter to control a motor of larger than normal full load current When using an inside delta connection a main contactor or shunt trip MCCB must also be used to disconnect the motor and soft starter from the supply in the event of a trip y PS Q1 or X
80. 280 00A SWITCHGEAR Vacuum circuit breakers Typical characteristics Environment Indoor Operating current 3000 A Operating voltage lt 36 kV Fault current rating 31 5 kA Contacts One fixed and one moveable copper chromium switching contact per pole with a contact separation distance of 10 15 mm Contacts reside in a vacuum within a totally sealed cast resin enclosure Arc extinguishing properties good Typical characteristics Environment Indoor outdoor Operating current 4000 A Operating voltage lt 52 kV Fault current rating lt 50 kA Contacts One fixed and one moveable copper chromium switching contact per pole with a contact separation distance of 10 15 mm Arc extinguishing properties quick and efficient Special design techniques use compressed sulphur hexafluoride gas to extinguish the arc Oil circuit breakers These circuit breakers use an oil blast method to extinguish the arc When the switching contacts separate the arc vaporises the oil surrounding it This produces a gas which inhibits arc ionisation At the same time convectional movement of the oil aids in cooling after the arc has been extinguished Due to oil fire hazard these circuit breakers are generally used for outdoor applications only and are being replaced in indoor applications Mechanical operation Circuit breakers are electromechanically driven using magnetic or stored energy techniques
81. 3 C54 Programmable input A 2 To motor C63 C64 Programmable input B A2 Control voltage terminals 6 Programmable outputs 3 Control supply 43 44 Programmable Relay output A A3 Power interface PCB 51 52 54 Programmable Relay output B 4 Relay outputs 61 62 64 Programmable Relay output C C73 C74 Bypass contactor feedback signal 7 Motor thermistor input 13 14 Main contactor KI 8 Analog output 23 24 Bypass contactor K2 A5 Communications module optional 33 34 Run output PFC 710 12280 00A Medium Voltage Application Guide Page 33 SOFT STARTERS MVX Soft Starter Overview The MVX provides compact and robust soft start solutions for control of medium voltage motors MVX soft starters provide a complete range of motor and system protection features and have been designed for reliable performance in the most demanding installation situations Each MVX soft starter comprises e a Phase Cassette e a Controller module The Phase Cassette and Controller module are supplied as a pair and share the same serial number Care should be taken during installation to ensure the correct Controller and Phase Cassette are used together NOTE Feature list Starting e Constant current e Current ramp Stopping e Coast to stop e Soft stop Protection e Under Overvoltage e Mains frequency e Phase sequence e Shorted SCR e Motor overload thermal model H nstantaneous overcurrent e Time overcurrent e G
82. 4 VDC 8 mA approx Input B Terminals C63 C64 24 VDC 8 mA approx Motor Thermistor Terminals Eh ememr Trip point gt 2 8 kQ NOTE IN All control inputs are potential free Do not apply external voltage to these inputs Low Voltage Supply Rated Voltage MVXxxxx V 85 275 VAC ated nr AE 50 60 Hz Typical power consumption MVX gt oxxx V I Start Stop Outputs EVA M 10 A 250 VAC resistive T 6 A 250 VAC ACI5 pf 0 3 10 A 30 VDC resistive 24 VDC 8 mA approx Outputs on interface PCB Main Contactor 13 14 Bypass Contactor 23 24 Run Output PFC 33 34 Outputs on Controller Normally Open Normally Open Normally Open Output CC M M y Open Output Relay B 51 52 54 ngeover Output SEES IM M c Changeover Analog Oute LOC CCRA 0 20 mA or 4 20 mA Environmental Degree of Protection Phase Cassette emgeet cte tetti tatu cupri b cup Put ctu eti sut IP00 Controller mounted on a panel netten IP54 NEMA 12 Operating Environment EC60721 3 3 IE34 Climatic 3KA4 5 C to 40 C with derating to 55 C Relative aisle rr EE 5 to 95 Storage Environment zm pH Mp 5 C to 55 PC serus aen 5 to 95 POUN DESEE hiarr eiai T Pollution Degree 2 leue IEC 60068 2 6 Fc EMC Emission EquipmentGlass EMG usitato bitrate ptas tt
83. 5 times continuous operating voltage U U 1 25 x15 U 2 18 75 kV ominal discharge current For a secondary distribution system use a lightning impulse nominal discharge current rating I of 10 kA e Residual protection voltage D The residual protection voltage U developed across the MO arrester when discharging 10 kA must be ess than 70 of the equipment lightning impulse rating U Uu lt U x 0 7 lt 95 x07 lt 66 kV Step 2 Using the calculated ratings select an MO arrestor from the manufacturer s data sheet Page 134 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Solution A type MWDI5 meets the selection criteria Type R d d Resided voliage U in kV pk at specified impulsa current Qontinuaus Fated voege pperstng Wave 1 us Wee 8 20 jis Wave 30 80 ps volage kV rms Ls kY rms _1 WA pk GkApR 10 kA pk TkA pk OA px PU kA pk 125A pk 250 A pk 00 A pk n m 50 4 10 5 1258 104 ms 13 6 9 0 8 5 Su t02 43 5 13 1 160 130 45 17 0 13 11538 12 3 12 8 7 5 h 157 192 156 74 20 4 134 14 3 14 8 15 4 n n 15 3 224 16 2 aS 23 8 15 8 36 7 17 2 17 9 10 0 H 210 256 20 8 232 222 181 19 0 19 7 205 113 3 23 6 259 23 4 26 1 30 6 203 214 221 230 125 10 262 321 26 0 290 34 0 225 238 24 6 23 8 138 1 2B 8 353 28 6 319 37 4 249 27 1 28 2 16 0 12 31 4 355 312 MS 408 771 29
84. 7 A 710 12280 00A Medium Voltage Application Guide Page 65 SOFT STARTERS Slip ring motor control The principle of a slip ring motor is that external rotor resistance provides the necessary motor torque during acceleration to full speed Once the motor is close to full speed the external rotor resistance is shorted out and the motor operates as a standard three phase induction motor Old slip ring motor systems typically consist of a liquid resistance tank with an electrode or else a series of cast iron or wire wound resistor banks with a changeover switch These systems require mechanical intervention for motor starting can become mechanically unreliable and require regular maintenance AuCom medium voltage soft starters include a unique function specifically for slip ring motor control This function is not suitable for applications where a slip ring motor is being used for speed control or to develop excess start torque ie more than 100 motor full load torque to break away Some rotor resistance is required in order to start the motor This rotor resistance R1 is shorted when the motor is close to full speed using rotor resistance contactor K3 The contactor must be AC2 rated for the nameplate rotor current AuCom medium voltage soft starters use a Dual Ramp start function This provides a voltage ramp with constant current control while the rotor resistance is in the circuit This is followed by a smooth transition
85. AuCen Contents oe e 4 2 Mere m 5 2 commo types of industrial motors icit t tlm tti a RE t Dni tne n cd 5 IEE OA Re ee 5 Eleefkkgrpgd e a D 6 SII PIS ACEO IS E 7 SYMGMFOMOUSIMOLO MS es ees ees Ra sU A MN eal ee MUN MU E 9 2 2 Motor startinigietbiods d ee eS MEME M MEME 0 ee Oe 0 PRIMARY resistarice ETH iso e casks ties e cua iet ee aee ente ate dae dta efe eee Auto transforimer EE ET 3 Stars Delta Starting nirai oo oo Rn tam lana en bud ole Ee bue Lb alat LH TET s 5 SOFT STATES anisan aan M 6 Varlabl frequeney Dee NH 7 3 Soft Starters en 19 3 1 What is a Soft Starter 9 Open eent tbe 20 Closed loop sott Start OBEtFOl aio atto e M nM PUO URS P OM gu Ga Des Ate 2 32 Benefitsz out e tL uunc cce 22 Electrical Bemettte aseene tq ade dq RR Sto 22 IMechanical Benefitss 51 itte odisti nin ANEKA dE e dE 22 Application Benefits 222 3 3 Anatomy 223 Key components 223 SCRS coim KE Snubber circuits 2A lnc TS 24 E e 25 Bebe MD A 25 EU 25 PGBS ictum tacts Ment ea NENTA E OENE E cited 25 aee 25 Common functienality and features Eeer 26 34 AuGomy Medium Voltage Soft Starters EAR 29 MYS Soft Statens aAA KENANA RA AARNA NANA A EEN AEN
86. C classification Switchgear which passes indoor testing is also considered suitable for outdoor use with the same accessibility requirements Accessibility is divided into two categories Type A is for authorised personnel dressed with adequate protective equipment and Type B for general public access Equipment is also tested for different directions of access front rear or lateral side Cotton cloth indicator panels are placed 2 m above ground level and on each accessible side of the equipment under test If pressure relief ducts are part of the switchgear design these must also be subjected to cloth indicator panel testing Tests are carried out by supplying a predetermined level of fault current for a specific duration Using various test procedures the applied fault current creates an internal arc to ground within a specific region of the switchgear In general test results are considered acceptable if e correctly secured doors and covers do not open deformation is acceptable providing it doesn t protrude as far as the indicator panels e no fragmentation of the enclosure occurs within the test time small particles up to 60 g are acceptable e arcing does not cause any holes in the accessible areas up to a height of 2 metres e indicator panels do not ignite due to hot gas emissions e the enclosure remains connected to its earth point verified by a continuity test IAC certification example
87. Cables Zee 0 1 O km Busbars Z 0 15 Q km Page 158 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Impedance Method Calculations Case eer gr ource etwork e Feeder U 36KV 80 3X A 3 S 1000 MVA Transformer TR U 36kV 11 kV 50 Hz 20 MVA Z 10 13851 A Generator G kv 50 Hz 5 MVA 5 20 For the purposes of this calculation ignore all impedances of circuit breakers cables and busbars The first step is to calculate the individual impedances Generator impedance Zo Z LU Xe US 100 dd 45 x 15 100 1 210 The subtransient impedance is 1 2 Q U A s x S 100 i 20 15 100 1 60 The transient impedance Is 1 6 Q U 2 Z ES ye R sm d 20 100 0 610 The permanent impedance is 0 6 Q Transformer impedance Zp Network impedance Ze as seen on the U 2 z 40 y Us secondary side of the transformer NET Sa U Q9 IT 1000 Le 1 30x0 31 0 120 The permanent impedance is 0 12 Q 710 12280 00A Medium Voltage Application Guide Page 159 SWITCHGEAR Short circuit impedances and ratings of switchgear devices Device Equivalent circuit Short circuit impedance Break rating Make rating Q kA rms kA peak CBI i Transient stage Z 160 ZG lt S Get Subtransient stage 2254529 Z 120 13 23 kA CB2 ieee Zsc duech Za 43 x0 72 2 5x8 82 0 12 0 6 _ 1 0720 7125 22
88. Guide 710 12280 00A SWITCHGEAR Minimising the effects Certain design techniques are used to provide a high level of safety to personnel by minimising the effects of internal arcing e compartmenting of enclosure e pressure relief methods e double skin panels e arc venting away from access areas e remote control of switchgear e rapid fault clearance Rapid fault clearance requires fast detection and isolation of the arc This can be achieved using e light heat or pressure sensors combined with a relay to trip a fast acting circuit breaker e pressure operated earth switch capable of diverting the internal arc to ground arc eliminator e fast acting current limiting line supply fuses 710 12280 00A Medium Voltage Application Guide Page 87 SWITCHGEAR 4 4 Switchgear Apparatus Medium Voltage Circuit Breakers A circuit breaker is a main switching device providing control and protection of an electrical circuit It is a very fast acting device capable of switching high fault current levels Some medium voltage circuit breakers have integrated current monitoring and protection facilities but in most cases external current transformers and a protection relay are required to trip the circuit breaker under abnormal conditions 13680 A A circuit breaker must operate under various conditions without damage or safety risk to personnel e acircuit breaker operates mostly in the closed position and m
89. Incoming and motor supply configuration MV soft starter panels can be constructed for standalone use or with a horizontal busbar system for an MCC line up If the soft starter panel will connect to a different switchgear style busbar system a termination or transition panel will be required All panels can accommodate top or bottom exit for the outgoing motor cables Standalone MV soft starter panel Incoming supply Front view top or bottom cable entry z 13521 A Motor cable top or bottom exit o EE Bros Bee fee Bo Typical MCC panel line up aJ Existing switchgear panel pa Transition panel Soft starter MVS E3 panels LM Mains supply busbar system p 13522 A Page 50 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Customer specific requirements Additional equipment can be designed and integrated into AuCom MVS and MVX panel solutions depending on the customer s specific needs In some cases extra switchgear panels matching the soft starter panels may be required in order to house the extra equipment Motor protection relay in addition to soft starter motor protection RTD PT100 temperature protection relay nsulation monitoring relay Predictive Maintenance Module PMM Metering relay PLCs auto changeover contactors PFC controllers etc nverters and switch mode power supplies Low voltage control equipment e
90. P00 SCRs a TUS NN E e E SCRs silicon controlled rectifiers also called thyristors are the primary component of any soft starter The SCR is a controlled diode that only allows current to flow in one direction An SRC has three terminals When the gate terminal is triggered with a low voltage signal the SCR is turned on This allows current to pass through from the anode to cathode terminals An SCR is self commutating and current stops flowing when it reaches the zero point crossing A soft starter has at least two SCRs per phase connected in reverse parallel configuration so that current can be controlled in both directions The soft starter can con There are two physical styles of SCR trol one two or all three phases modular pack SCRs are a self contained reverse parallel device These are often found in low voltage soft starters with a voltage range of 200 VAC to 690 VAC and a current rating less than 300 A disk or hockey puck style devices are a single SCR which needs to be electromechanically configured in reverse parallel configuration for soft starter use This style of SCR is used on higher current rated low voltage soft starters with current ratings greater than 300A Medium voltage soft starters with an operating voltage range of 2 3kV to 3 8kV always use disk style SCRs connected in series for each half of a phase to obtain Modular SCR the necessary volt
91. Specifications The following soft starter and power factor panel specifications provide detail of AuCom supplied equipment The switchgear specification is more generic These specifications can be used entirely or in part when tendering for a project NOTE IN AuCom reserves the right to modify or change the specification of its products at any time without notice Page 182 Medium Voltage Application Guide 710 12280 00A SPECIFICATION MVS Solid State Reduced Voltage Motor Starter MEDIUM VOLTAGE CONTENTS Contents DEAE UCU OIA DUET TREE 2 AVN Kee 2 1 2 Supplier Oualtftcattons nenne 2 Environmental Speclficallons oii iod Ie ee eee es eee eee 3 2 1 Environmental Specifications sseesseeseeeeeese enee eeetr ee terttntnetennnrrnnrrnnrrne e 3 2 2 Physical Gpechflcations nennen 3 CN EE 3 Logic Control Confiqurallon eege ee 4 3 4 Control Interface onte te eaten t ian eds 4 3 2 Operating Configurations ssssssssesssseseenenneee nennen 5 3 3 Motor and System Protection Features 5 3 4 Programmable Relay Outputs nnns 6 3 5 Programmable Control Inputs sse 6 3 6 Metering and Performance Monitoring sse 7 3 7 Remote Communications eene 7 Support atid Papeete EE tese un EE cese Eege Eege 8 4 1 X Commtssioning seen aea aa asaite iei snnt inttr 8 4 2 DOCUMENTATION iR EE RR GA Herr ERI RE ERR OR 8 e GC ENN EC
92. Start time seconds Start current multiple of motor full load current ter current rating amperes Starter current rating The full load current rating of the soft starter given the parameters detailed in the remaining sections of the utilisation code Start current The maximum available start current Start time The maximum allowable start time Off time The minimum allowable time between the end of one start and the beginning of the next start 1 Start current 350767 5 se time t oe This includes time while the p starter is running but the SCRs are g Ju not conducting 100767 lt 4 Nominal motor current NOTE IN AuCom MVS and MVX soft starters are AC53b rated and must always be used with a bypass contactor or circuit breaker 710 12280 00A Medium Voltage Application Guide Page 53 SOFT STARTERS 3 6 Calculations What is the minimum start current with a soft starter Soft starters can limit start current to any desired level However the minimum level of start current for a successful start depends on the motor and load To start successfully the motor must produce more acceleration torque than the load requires throughout the start Reducing the start current also reduces the torque produced by the motor The start current can only be lowered to the point where the torque output remains just greater than the load torque requirement The likely start current can be estimat
93. The main standard applying to MV voltage transformers is 61 869 3 Nominal voltage Example 3 3 kV 110 VAC Denotes a primary phase to phase voltage rating of 3300 V and a secondary phase to phase voltage rating of 10 VAC 3300 110 VAC 13762 A Example 3 3 kV N3 110 N3 VAC Denotes a primary phase to phase voltage rating of 3300 V and phase to earth rating of 1905 V ie 3300 x V3 and a secondary phase to phase voltage rating of 10 VAC and phase to earth rating of 63 5 VAC ie 110 x N3 3300 3 110 V3 VAC 13763 A 710 12280 00A Medium Voltage Application Guide Page 127 SWITCHGEAR Many manufacturers use a continuous overload rating of 2 times the primary voltage rating without exceeding thermal capabilities which can lead to winding and insulation failure Output power This is the apparent output power rating of a transformer when nominal voltage is applied to the primary For a 3 phase voltage transformer Where arrangement S V3 x U x S apparent output power VA U secondary line voltage rating V For a single phase voltage transformer secondary line current rating A arrangement S U x Standard values are 10 15 25 30 50 75 100 120 VA Control supply power transformers are usually single phase transformers with an output power rating of 500 VA to 5000 VA For further details refer to Control power supply transformer sizing on page 128 Accuracy class De
94. a short circuit fault In the event of short circuit current flow l the surface temperature of a busbar must not exceed the thermal limits of any material coming in contact with it ie insulator standoffs e Check the maximum expected electrodynamic forces imparted on the busbars and insulator standoffs due to the peak short circuit fault current I e Check that the busbar system wi dyn Refer to Busbar Calculations on page 149 for calculation details and examples Busbar bolting arrangements Typical busbar bolting details for single overlap copper bar Do not exceed the mechanical limitations of the material not resonate under normal operating and fault conditions Bar width Joint Joint area Number offMetric bolt size Bolt Hole size Washer Washer mm overlap mm bolts coarse thread torque mm diameter thickness mm Nm mm mm 16 32 512 2 M6 72 7 14 1 8 20 40 800 2 M6 72 7 14 1 8 25 60 1500 2 M8 7 0 21 2 30 60 1800 2 M8 7 0 21 2 40 70 2800 2 MIO 28 11 5 24 2 2 50 70 3500 2 M12 45 4 28 2 7 60 60 3600 4 MIO 28 1 5 24 22 80 80 6400 4 MI2 45 4 28 2f 100 100 10000 5 MI2 45 5 28 2 7 120 120 14400 5 MI2 45 5 28 2 7 160 160 25600 6 MI6 9 20 28 2 7 200 200 40000 8 MI6 9I 20 28 2 7 Source Copper for Busbars http www coppennfo co uk busbars pub22 copper for busbars homepage shtml Numbe
95. a single stage of rotor resistance soft starters can be successfully applied to slip ring motors Refer to Sip ning motor control on page 66 for further details Page 8 Medium Voltage Application Guide 710 12280 00A MOOLS The construction of a synchronous motor stator is the same as a standard induction motor although the stator configuration is such that relatively low operating speeds are common eg 300 600 rpm Synchronous motors When 3 phase voltage is applied to the stator windings a magnetic field is generated which rotates at a synchronous speed around the stator and rotor The synchronous speed is determined by the stator construction and frequency of the supply voltage Motor synchronous speed Where N synchronous speed rpm f mains supply frequency Hz p number of stator pole pairs The rotor design incorporates a squirrel cage winding combined with a DC excitation winding This allows the motor to start as a standard squirrel cage induction motor reaching a running speed of approximately 95 synchronous speed At this point a DC voltage is applied to the excitation winding via a slip ring and brush arrangement A fixed magnetic field is created in the rotor which locks in with the rotating magnetic field of the stator The motor shaft now runs at synchronous speed Synchronous motor Fan inside H Excitation rings x2 Three phase stator windings DH Rotor with poles and exci
96. actor as a main switching device a fixed bypass contactor overvoltage MOVs on the line side and an earth switch on the motor side Refer to the MVX section for details of optional panel equipment The panel can be supplied as a stand alone format or with an upper horizontal busbar system for an MCC switchgear line up Typical MVX contactor panel HM Three phase supply MV protection fuses x3 RH MVX contactor panel Main contactor withdrawable fused MVX soft starter CT 1 3 Current transformers Overvoltage MOVs Page 180 Medium Voltage Application Guide 710 12280 00A SCHEMATIC DIAGRAMS This panel option is currently supplied for a maximum motor FLC of 400 A It consists of a withdrawable circuit breaker as a main switching device a separate motor protection relay MPR a fixed bypass circuit breaker overvoltage MOVs on the line side and an earth switch on the motor side Refer to the MVX section for details of optional panel equipment Circuit breaker panel option The panel can be supplied as a stand alone format or with an upper horizontal busbar system for an MCC switchgear line up Typical MVX circuit breaker panel 14052 A o Three phase supply OI Main circuit breaker withdrawable MVX circuit breaker panel SC circuit breaker fixed B pos 7 AL MVX soft starter UI 3 Overvoltage MOVs CTI3 710 12280 00A Medium Voltage Application Guide Page 181 Resources 6 1 Equipment
97. aded or unloaded starts Page 12 Medium Voltage Application Guide 710 12280 00A MIO en Auto transformer starting Auto transformer starters use an auto transformer to reduce the voltage during the start period The transformer has a range of output voltage taps which can be used to set the start voltage and the start time is controlled by a timer The motor current is reduced by the start voltage reduction and further reduced by the transformer action resulting in a line current less than the actual motor current The initial line current is equal to the LRC reduced by the square of the voltage reduction A motor started on the fifty percent tap of an auto transformer will have a line start current of one quarter of LRC and a start torque of one quarter of LRT Ifthe start voltage is too low or the start time is too short the transition to full voltage will occur with the motor at less than full speed resulting in a high current and torque step The simplest auto transformer starters are single step and often control two phases only More sophisticated starters may step through two or more voltage steps while accelerating from the initial start tap to full voltage Auto transformer starters are usually rated for infrequent starting duties Frequent or extended start rated auto transformers are large and expensive due to the heating in the transformer Auto transformer starters can be constructed as
98. age rating Disk style hockey puck SCR 710 12280 00A Medium Voltage Application Guide Page 23 SOFT STARTERS Snubber ci rcuits Snubber circuits are used to suppress a phenomenon called notching which occurs at the zero voltage crossing point Snubber circuits provide SCR control stability and a level of overvoltage protection In the simplest form a snubber is a resistor capacitor network connected in parallel across each SCR Resistors used for this purpose are typically wire wound for the necessary power rating In medium voltage soft starters grading resistors are connected in a series parallel configuration across all SCRs This divides the voltage across SCR in each phase evenly Basic LV snubber arrangement LV supply MV supply Heatsinks 13490 A Motor 13489 A gr 0 RC snubber network Bros Motor Heatsinks are designed to efficiently dissipate the heat generated by SCR switching during motor starting and stopping Opti mum heatsink design temperature below 30 C SCRs are alwa e mod e fordi ys bonded to a heats ular SCRs are bonded sk SCRs the conduct Many soft starters reduce the heatsi arrangement during motor running maximises to an Isola the rating of the soft starter by keeping the SCR internal junction nk using an appropriate thermal paste ted heatsink arrangement ng faces of each SCR are compressed against a con
99. ain repeated motor start overload currents without degradation Fuses are installed to provide short circuit protection only and the motor circuit must have separate overload protection Fuse selection for a motor application is typically carried out using graphs provided by the fuse manufacturer These graphs consider motor starting current A motor run up time s and starts per hour Typical fuse ratings for 2 4 or 8 starts per hour starting time lt 60 seconds H Starts per hour 8 2x315 4 2 2 x 200 315 250 200 160 Fuse rating A 100 63 13697 A 200 1000 1000 Motor starting current A Typical fuse ratings for 2 4 8 16 or 32 starts per hour starting time lt 15 seconds 1 977 H Starts per hour C 2x315 2 x 250 2 x 200 315 250 NAROD 200 Fuse rating A 160 100 13745 A 63 200 1000 10000 Motor starting current A Source example curves based on ABB CMF fuse links Exercise A 3 3 kV motor has a full load current of 150 A Its expected start current is 5 5 times full load current for 0 seconds and it operates at 2 starts per hour Select the required protection fuse Use the graph for Starting time lt 15 seconds The start current will be 5 5 x 150 A
100. ak switch with minimal short circuit making and breaking current capacity Back up short circuit protection fuses must be used the contactor manufacturer will specify the maximum allowable fuse size The switching contacts are sealed inside the vacuum interrupters and mechanical operation uses the magnetic technique 13681 A Medium voltage contactors are suitable for high frequency switching gt 10 000 operations with continuous AC current ratings greater than 800 A and rated voltages from kV to 12 kV Manufacturers provide standard utilisation category ratings which can be matched to a specific application and the required number of operations Indoor contactors can be fixed or withdrawable style Withdrawable style contactors can usually house primary protection fuses Withdrawable style contactor Fixed style contactor ASS Construction Medium voltage contactors usually consist of e flame retardant plastics to house the vacuum interrupters and fuses in the case of a withdrawable contactor e metal chassis and truck in the case of a withdrawable contactor e busbars for main power circuit connections or cluster style power connections in the case of a withdrawable contactor e magnetic and mechanical linkage components for operation of the vacuum interrupter contacts e auxiliary circuit components such as auxiliary contacts truck position contacts undervoltage or shunt trip coils interlock coil etc
101. al faults at numerous locations causing a wide range of physical damage Internal Arc Classification IAC of metal enclosed switchgear considers the damage that can affect covers doors inspection windows ventilation openings etc as a result of overpressure within panel compartments IAC also takes into consideration damage from thermal effects ejected hot gases and molten particles Internal arc classification When selecting metal enclosed switchgear the probability of internal arcing and the safety risk to operators and the general public needs to be considered Where the safety risk is considered relevant the switchgear should be IAC classified The IAC classification indicates the maximum fault current level and duration to which the switchgear has been tested When choosing switchgear the IAC rating should exceed the expected fault current level and duration at the point of installation The rating also takes into account the accessibility of the switchgear IAC tested and certified switchgear must always be clearly marked with the classification fault level and duration and accessibility of each side Relevant standards and testing The primary standard for internal arc classification of medium voltage metal enclosed switchgear is IEC 6227 200 IEC 6227 202 is also relevant IEC 62271 200 details test procedures to assess damage to switchgear from internal arcing Test results provide the switchgear with an IA
102. al to the primary current Accuracy is typically 1 up to 10 times the rated primary current and 5 up to 200 times the rated primary current The customer must specify the required nominal primary current short time fault current withstand rating and the insulation level requirements No other specifications apply as rogowski coils are supplied by the manufacturer as a matched item with the associated relay device JO Current to be measured RH Secondary winding Non ferromagnetic support D Output voltage 13750 A Hall effect sensor Hall effect sensors consist of a semiconductor hall cell placed in the air gap of a magnetic circuit The strength of the magnetic circuit is directly influenced by the primary current The hall cell is supplied by a steady state current and the generated secondary output voltage is proportional to the magnetic field strength Inaccuracies in this measurement method are compensated for by using integrated digital circuitry Hall effect sensors are usually integrated into other equipment for measurement of AC and DC primary current H urrent to be measured Magnetic circuit cel D all cell supply current B all output voltage O Voltage or current amplifier Zero flux current transformer A zero flux current transformer consists of a single primary winding and a secondary made up of two windings on a toroidal magnetic core The fir
103. all the Contract Drawings will be provided to the Contractor Supplier upon receipt of the Contractor s Suppliers written request Electrical wiring and circuit diagrams shall be neat clear un crowded and shall show all equipment using standard symbols All electrical equipment wiring and terminals shall be numbered in accordance with the Specification requirements Project Manuals The Contractor Supplier shall supply manuals for the operation and maintenance of all electrical and instrumentation and control systems supplied under the Contract In addition the Contractor shall provide comprehensive manuals which detail the programming and configuration of any programmable systems The Contractor Supplier shall also provide an electronic copy of the manual In general sufficient information shall be provided to enable the plant s operations and maintenance personnel to understand the function of all equipment and its components and to correctly perform the required operation and maintenance Factory Testing amp Commissioning Test Sheets Contractor Supplier shall prepare detailed check sheets to record each phase and item of testing and commissioning as required by the Client The check sheets shall include separate items for each test and check of each input output and each step and sequence of functional operation Each item on the check sheets shall have provision for recording the date of the activity and name and signatur
104. amperes Starter current rating The full load current rating of the soft starter given the parameters detailed in the remaining sections of the utilisation code Start current The maximum available start current Start time The maximum allowable start time On load duty cycle The maximum percentage of each operating cycle that the soft starter can operate Starts per hour The maximum allowable number of starts per hour 9 9 B Starts per hour 4 D i i Run time 100964 md i 5 6 oe One dek 7 Nominal motor current Time 350 Current 09593 A Duty cycle Start time Run time Start time Run time Off time Page 52 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS he AC53b utilisation code defines the current rating and standard operating conditions for a bypassed soft starter internally bypassed or installed with an external bypass contactor AC53b Utilisation Code The soft starter s current rating determines the maximum motor size it can be used with The soft starter s rating depends on the number of starts per hour and the length and current level of the start The soft starter s current rating is only valid when used within the conditions specified in the utilisation code The soft starter may have a higher or lower current rating in different operating conditions 80A AC 53b 3 5 15 345 Off time seconds
105. ance starter 7x FLC 6 x FLC 5xFLC 4x FLC 3 x FLC Current 2x FLC 1x FLC 10 20 30 40 50 60 70 80 90 100 Speed Torque a Full voltage start current 2 Primary resistance start current 3 H Full voltage torque 4 Primary resistance torque 5 Start performance characteristics of an incorrectly selected primary resistance starter 7x FLC 6 x FLC 5xFLC 4xFLC 3xFLC 2xFLC Current 1xFLC 1096 20 30 2x FLT 1x FLT 40 50 60 70 80 90 100 Speed Torque How does soft start compare to primary resistance starting Compared with primary Primary resistance starters offer limited performance because 1 Full voltage start current 2 Primary resistance start current Ful voltage torque 4 Primary resistance torque Stall point D Current and torque transient resistance starters soft starters are more flexible and reliable e Start torque cannot be fine tuned to match motor and load characteristics e Current and torque transients occur at each vo e They are large a e liquid resistance versions require frequent main nd expensive e Start performan controlled e They cannot accommodate changing load cond e They cannot provide soft stop tage step tenance ce changes as the resistance heats up so multiple or restart situation are not well itions eg lo
106. andard for Metal Clad Switchgear Internal arc resistance High Voltage switchgear amp control gear Part 200 AC metal IEC6227 200 enclosed switchgear and control gear for rated voltages from Annex A 6 criteria to kV to 52 kV 5 EEE Guide for Testing Medium Voltage Metal Enclosed IEEE C37 20 7 NEC Switchgear for Internal Arcing Faults IE E nsulation coordination Part Application guide IEC60071 2 Evaluation and qualification of electrical insulation systems IEC60505 nsulation coordination for equipment within low voltage systems Part Principles requirements and tests Dry solid insulating materials Resistance test to high voltage ow current arc discharges Degrees of protection provided by enclosures IP ratings amp tests Classification of groups of Storage EC60721 3 environmental parameters and their severities Transportation IEC60721 3 2 IEC60068 2 32 Insulation tion coordinati finitions principles and EC60071 1 Page 68 Medium Voltage Application Guide 710 12280 00A 4 Switchgear This section provides information and guidance on the design of metal enclosed medium voltage switchgear panels and associated switchgear apparatus If further information is required refer to the appropriate international standards or contact your local AuCom representative AuCom offers MVS and MVX soft starters in their own unique pane
107. aniples of differencesin ratingirequibertienits Au 67 49 IEG Switchgedr Rating Eelere 68 EE 68 VE le 68 Frequency fr Hz dod dod tci enel dert Ae tg 69 4 10 Protection If dex se e UU a Ud UR REIR IRL IRA DDR RIEF 70 IP cup Y 70 NEMA Ratings 2 e PU pne Ro a HR er te om ee a AL H 5 SEH IG e Diderar iss ed nOD URRUUR RAND GOENTEH REGAIN UD OH UER aO UMEN GM RRN 5 Electrical Symbols Common Switching Functions 52 Circuit Breaker Control Typical en 5 3 Et Gontro ee 5 4 A t matie Changeover Systems nuda it RO ad tO uM MM e E 5 5 Een e RE Page 2 Medium Voltage Application Guide 710 12280 00A CONTENTS EE Deler i R al sachet E E E E MM ME MH 78 SH Bee 79 5 6 NS Schematic EAST AAS vote bad Rad MM MEM 80 Contactor palielOptlOElss ssusssscn tene ra VM M RUTRUM RN CLAMOR IA UNAN NRN 80 Circuit breaker panel DEELEN n devi ote RR dle 8l 6 iced s p 182 6 1 Eq ipmernt Specifications zi oo Ria aliod ao alte ote Reda tee ne ted 82 6 2 Metric lmpe rial Conversion Factors engen Seele 216 6 3 Wire Diameter Conve rsionit ss asl ossa ira anale aede ela AAA 217 6 4 UES E a A EE EE E IE O E ET IEA AA A A A TR 218 6 5 ComrnonlyUsed AbBreviations uua aoi A D PARU ade 219 7 RST SNCS cele AE DM D MEE 221 710 12280 00A Medium Voltage Application Guide Page 3 INTRODUCTION l Introduction This reference gu
108. are available in this style of enclosure Fanel compartments a Busbar compartment Cable compartment Switching compartment Low voltage compartment 11158 A Busbar Compartment The busbar compartment houses the main busbar system which is connected to the fixed upper isolating contacts of the main switchgear apparatus by means of branch connections The main busbars are made of high conductivity copper The busbar compartment of each panel is isolated from the busbar compartments of the neighbouring compartments Single or double busbar configuration is used depending on the current rating Cable Compartment The cable compartment houses some of the following components e Branch connections e Earthing busbar e Earth switch e Power cables e Surge arrestors e Instrument transformers current transformers voltage transformers Switching Compartment The switching compartment houses the bushing insulators containing fixed contacts for the connection of the switching apparatus to the busbar and cable compartment The bushings are single pole type and are made of cast resin They are covered by metallic shutters The metallic shutters operate automatically during movement of the switching apparatus from the test position racked out to the service position racked in and vice versa Shutters may be locked if required The position of the switching apparatus can be seen from the front of the panel through
109. at altitudes up to 1000 m above sea level without derating The equipment shall be suitable for use in environments with relative humidity between 5 and 95 non condensing 2 2 Physical Specifications The equipment shall be suitable for supply in IPOO format or integrated into a stand alone package The equipment shall be modular in design and construction The thyristor assembly for each phase shall consist of a discrete module and be individually replaceable Replacement of a thyristor assembly by a qualified service technician shall not take longer than 10 minutes No single module of the equipment shall exceed 80 kg in weight The integrated starter must be enclosed up to IP54 and include e Line contactor Bypass contactor e Line fuses optional e A pad lockable earthing Isolator optional 2 3 Safety The equipment shall employ only air insulation between phases The IPOO starter should be capable of being enclosed without any additional clearances at the side of the product The equipment shall employ fibre optic cabling to ensure complete isolation between low voltage and high voltage circuitry The equipment shall provide means to safely test its correct installation e The equipment shall provide a means to test the installation using a low voltage motor e The equipment shall provide a means to test operation of all control circuitry and protection mechanisms without connection to medium voltage Func
110. ault current rating l No continuous overload capability No switching capability Used with a circuit breaker or contactor and fuse combination Switch Disconnector Switching and isolation Rated for carrying continuous load current with load break isolator a short time withstand fault current rating I Can switch rated current I but has no fault make capability Used with line fuses or a circuit breaker Earth switch Earthing Rated for carrying continuous load current with a short time withstand fault current rating l No load switching capability but can make on a fault 1 Used with a circuit breaker or contactor and fuse combination Gas insulated Earth disconnector Switching isolation and Rated for carrying continuous load current with fixed or rotary earthing a short time withstand fault current rating l Can switch rated load current I Can make on fault current l Used with line fuses or a circuit breaker Applications A typical medium voltage metal enclosed switchgear feeder circuit will have a combination of switchgear able to provide the following functions e switching of load current e short circuit protection e means of isolation e means of earthing In most cases air insulated earth switches or gas insulated earth disconnectors are used The following examples show common configurations for medium voltage metal enclosed switchgear feeder circuits Page 100 Medium Voltage Applicatio
111. bar system can be tapped off the main horizontal system for incomer feeder bus coupler bus riser metering or motor starter circuit i 8 mm S ur re is sl Ga m d E eu wi ER Ratings 11185 A The nominal current rating l of an incomer busbar system usually matches the rating of the main busbar system it is feeding Likewise bus coupler and bus riser systems have the sam e current rating as the main busbar system they are connecting A feeder circuit busbar system has a nominal current rating to match the expected load The nominal current rating is determined by the cross sec ividual phase bars tional area shape and configuration of the The short time withstand current rating lj of the busbar system m ust be greater than the highest expected symmetrical fault current at the point of installation This rating is for a short time withstand period of or 3 seconds t All busbar systems installed in the same switchgear line up usually have the same short time withstand current time rating The nominal frequency rating f of a busbar system must match th The nominal voltage rating U of a busbar system must be greater than the installation s operating voltage This voltage rating determin
112. be in English The Client will either 1 Review the submittal or 2 Review the submittal subject to notations or Where the submittal is reviewed it will be so endorsed by the Client and one copy returned to the Contractor Supplier The Contractor Supplier shall make the required alterations and transmit the required copies of the altered submittal All work under the Contract shall comply in all respects with the submittals reviewed by the Client described above Review by the Client of any drawing method of work or any information regarding materials and equipment the Contractor proposes to furnish shall not relieve the Contractor Supplier of responsibility for any errors therein and shall not be regarded as an assumption of risks or liability Such acceptance shall be considered to mean only that the Client has no objection to the Contractor Supplier using upon the Contractor s own full responsibility the plan or method of work proposed or furnishing the materials and equipment proposed Quality Assurance The Contractor Supplier shall be ISO 9000 certified The Contract Supplier must provide certification compliance and demonstrate this to the Client DOCUMENTATION Documentation 2 1 2 2 2 3 Drawings Unless approved by the Client all drawings shall be prepared using AutoCAD or an approved computer aided drafting CAD package All drawings shall be A3 size CAD files of
113. cable Calculate the minimum required VA rating of the CT kx VA case kx S 0 0176x 22 25 0 14 VA V Aneres 3 V VA xor 0 14 3 3 14 VA The total burden Is 3 14 VA Usea 5 VA CT 2 ACT with a 5 A secondary is connected to a digital protection relay located 2 metres away using 1 5 mm copper cable Calculate the minimum required VA rating of the CT VA oe ket 0 44x 4 1 5 21 17 VA VA_avmeter 1 V VA oi 7 1 175 1 22 17 VA The total burden is 2 17 VA Usea 25 VA CT Metering class A metering class indicates the accuracy of the CT secondary current at 5 to 125 of rated primary current Above this level the CT starts to saturate and the secondary current is clipped to protect the inputs of a connected metering instrument e general metering CT would use a metering class CL 0 5 1 0 e revenue metering CT would use a metering class CL 0 2 0 5 Operating range for metering class current transformer gg Linear operating range at accuracy class tolerance Flux b Se EC 5 125 13702 A le Page 12 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR A protection class CT provides a linear transformation of the primary to secondary current at high overload levels This characteristic makes them suitable for use with overcurrent protection relays A relay trip setting is normally 0 15 times the maximum load current and this level should fall o
114. cal cable length the cable capacitance must be negated by line inductance to avoid damaging current transients Air core line inductors are specified according to the installation and are fitted close to the soft starter output terminals eed EE 0 eii e LOE 3 phase supply oee E Soft starter SCRs are most vulnerable to current transient damage at two stages of the motor starting procedure e inthe initial ramp up to the start current current limit level e when the SCRs reach full conduction and just before the motor current falls to the running current level The latter stage is potentially more damaging AuCom medium voltage soft starters are bypassed in run state and the SCRs are turned off minimising the risk of current transient damage Current transient influences The di dt current transients that occur at SCR turn on are influenced by the following factors e System voltage and frequency e Total cable capacitance upstream and downstream of the soft starter e Motor characteristics kW efficiency starting power factor e Soft starter snubber component values RC network components e Control stage of the motor start up period e Start current current limit level Page 130 Medium Voltage Application Guide 710 12280 00A Saa Line inductor sizing Various software tools and calculation methods are used to determine the inductance value required f
115. ces including busbars Material and dielectric medium Maximum permissible Temperature rise temperature C above 40 C ambient CO Bolted connection or equivalent Bare copper bare copper alloy or bare aluminium alloy sulphur hexafluoride SF or nickel coated sulphur hexafluoride SF oll in coated air sulphur hexafluoride SF oll Source derived from IEC 6227 1 NOTE When engaging parts with different coatings or where one part is of bare material the permissible temperature and temperature rise shall be those of the surface material having the lowest permitted value Electrodynamic withstand During short circuit conditions the peak current associated with the first loop of the fault current produces electrodynamic forces which stress the busbar and insulator standoff supports Stress on the busbars must not exceed the limits of the material used Bending forces must not exceed the mechanical limits of the insulator standoffs Electrodynamic forces Busbars parallel Support h NM Fi TET Fo C 2 H i E ere 5 13678 A Id Distance between phases cm E Distance between insulators on a single phase cm Force on busbar centre of gravity daN Insulator height h Distance from head of insulator to busbar centre of gravity Force on head of insulator stand off daN
116. chanically interlocked to prevent both being closed at the same time The earth switch can only be closed once the circuit breaker is open and racked out to the test position The circuit breaker can only be racked in for closing once the earth switch is open An additional level of interlocking is required The incomer earth switch cannot be mechanically operated until power is removed from the incoming supply This prevents closing the earth switch onto a live supply This interlocking is achieved in one of two ways Mechanically by using key access The incomer earth switch E IL or E IR handle operation is only accessible by using a key retrieved from the upstream circuit breaker when it is open and racked out 2 Electrically by using a solenoid A solenoid is energised when the upstream circuit breaker is open and racked out allowing access to the incomer earth switch E IL or E IR handle operation Interlock scheme 3 Feeder circuit breaker and earth switch interlocking The feeder circuit breaker Q FL or Q FR and earth switch E FL or E FR are mechanically interlocked to prevent both being closed at the same time The earth switch can only be closed once the circuit breaker is open and racked out to the test position The circuit breaker can only be racked in for closing once the earth switch is open Page 84 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Metal enclosed switchgear can suffer intern
117. ct specification ANSI codes commonly specified for medium voltage feeders transformers motor and power factor banks ANSI Function Description Application Components code required CT 24 Volts per hertz Activates if the Volts Hertz ratio falls relay outside a preset range 25 Synchronising or Oper hen the voltage frequency synch ch and ph ngles between two AC 2 Incomer feeder Power factor 3 4 34 ee x 3 X 444 Jidd LL device system within a preset acceptable ran 6 Apparatus Activates if the monitored apparatus device exceeds a preset temperature 27 Undervoltage Activates if the voltage falls below a preset relay evel Undercurrent Activates if the current or power falls power relay a preset level 38 Bearing tivates when the upper temperature protective imit of a machine bearing is exceeded or d D evice bearing wear is detected hase reversal or it ine currents and activates w 46 current se reversal is detected or when lin imbalance relay current imbalance of negative phase sequence currents fall outside a preset range 47 Phase sequence nitors line voltages and activates w voltage relay phase reversal is detected 48 ncomplete Trips or turns off a device if a particular sequence relay sequence has not been completed within a preset time period 49 Machine or Activates if the monitored machine or PR transformer transformer part exceeds a preset thermal relay tempera
118. ctronic soft starters control the voltage applied to the motor by means of an impedance in series with each phase connected to the motor The impedance is provided by AC switches reverse parallel connected SCR diode or SCR SCR circuits The voltage is controlled by varying the conduction angle of the SCRs Soft starter control he SCR SCR switch is a symmetric controller which results in odd order harmonic generation he SCR diode switch is an asymmetric controller which causes even order harmonic currents to flow in the motor and supply Even order harmonics are undesirable for motor control because of the increased losses and heating induced in the motor and supply transformers Electronic soft starters come in two control formats e Open loop controllers which follow a timed sequence The most common open loop system is timed voltage ramp where the voltage begins at a preset start voltage and increases to line voltage at a preset ramp rate e Closed loop controllers which monitor one or more parameters during the start period and modify the motor voltage in a manner to control the starting characteristics Common closed loop approaches are constant current and current ramp Page l6 Medium Voltage Application Guide 710 12280 00A MOORS A variable frequency drive VFD converts AC 50 or 60 Hz to DC then converts the DC back to AC with a variable output frequency of 0 250 Hz The running sp
119. d Insurance Paid to destination named place of destination Buyer assumes risk when goods are received at the carrier Buyer assumes costs when goods reach the named destination CIF Seller arranges and pays for transportation and insurance to named Cost Insurance and Freight destination named port of destination Buyer assumes risk when goods are loaded on board the ship at the point of departure Buyer assumes costs when goods reach the named port of destination DDP Seller arranges carriage to the named place of destination ready for Delivered Duty Paid unloading named place of destination Buyer assumes risks when goods are available for unloading at the named place of destination Buyer assumes costs when goods are available for unloading at the named place of destination Page 218 Medium Voltage Application Guide 710 12280 00A RESOURCES 6 5 Commonly Used Abbreviations ACU Automatic changeover unit ANSI American National Standards Institute ATL Across the line ATS Automatic transfer switch BCP Bus coupler panel BRP Bus riser panel BIL Basic lightning impulse level kV peak DCO Double command operated DOL Direct on line FLA Full load amps A FLC Full load current A FLT Full load torque Nm f Nominal frequency Hz f Rated frequency Hz HP Horse power HRC High rupturing capacity AC Internal Arc Classification classification for
120. date of manufacture The supplier shall guarantee to provide servicing support for the equipment for a period of not less than 10 years 3 4 Standards and Approvals The equipment must as a minimum comply with and be certified to IEC 62271 200 IEC 60947 4 2 IEC 60664 IEC 60529 NZS4219 IEEE 242 IEC60871 CE EMC EU Directive C tick EMC Requirements Marine Lloyds SPECIFICATION Switchgear MEDIUM VOLTAGE CONTENTS Contents ld rere D ile SENSOR 2 1 1 ET 2 1 2 SUBMISSION EEN 2 1 3 Quality E EE 2 Doc mentat oN 3 2 1 Drawings itte pepe ap ite tei ttt 3 2 2 Project Manuals etie e aee idea etg 3 2 3 Factory Testing A Commissioning Test Sheets ssssnneesnnnnenennnneenn nenene neee 3 Electrical Supply 22 2 rr edicere re Nerei nd Io nee anes eae anes 4 3 1 General ett entes Ee batte ect ot fte tee dn 4 3 2 SHANG te 4 3 3 lee net EE 5 3 4 Material Quality eege tae ee tii aes 5 3 5 Busbar System ine neta HET etai cr ea ta ita iad eee 6 3 6 le KEE 6 3 7 Shi llers ie tac tat te ott us eit e eis 7 3 8 Earthing amp Earth Switch ssssssssssssseseseenennene enne 7 3 9 Cable Te rminatioris c unig aaa Ariel de ede AAR eee 7 3 10 Protection Relays siet tepidis 7 3 11 Current amp Voltage Transformers sssssssssseeeeeeeen nns 7 3 12 lc S M fades Deve 8 3 13 Control Wiring
121. dditional information on the International System of Units see http www bipm org Page 216 Medium Voltage Application Guide 710 12280 00A RESOURCES 6 3 Wire Diameter Conversion The American wire gauge AWG system is commonly used in the US and Canada to specify the diameter of electrical wires AWG number a a a standard metric equivalent mm 9 y 7 5 3 3 2 2 4 4 2 2 l 2 5 0 0 0 5 5 5 5 5 5 5 5 5 Source derived from ASTM 2002 and IEC 60228 NOTE UN This table does not provide a one to one correspondence between AWG and metric cables This table states the smallest standard metric cable which will provde at least as much carrying capacity as the AWG cable To substitute an AWG cable for a specified metric cable use an AWG cable with the same or greater cross section 710 12280 00A Medium Voltage Application Guide Page 217 RESOURCES 6 4 Incoterms International Commercial terms Incoterms are published by the International Chamber of Commerce and define the responsibilities costs and risks associated with the transportation and delivery of goods Key Incoterms for AuCom supplied equipment are EXW r arranges carriage from named place of delivery Ex Works r assumes risk when goods are made available named place of delivery r assumes costs when goods are made available CIP Seller arranges and pays for transportation and insurance to named port of Carriage an
122. de range of applications from pumps and fans to compressors and crushers By directly monitoring the voltage and current waveforms at the motor PMM can quickly and reliably detect changes in the characteristics and reports these through a streamlined easy to understand interface Because the PMM uses a model based fault detection and diagnostic system it is largely immune to noise making it ideally suited to erratic loads PMM can detect and identify a very wide range of mechanical electrical operational and efficiency problems affecting both the load and the motor itself e Mechanical loose foundation or components imbalance misalignment mechanical looseness deterioration of the couplings bearings or gearbox e Electrical loose windings stator fault insulation and capacitor breakdown supply problems damaged rotor bars bad connections phase imbalance e Operational abnormal loads cavitation filter blocking e Electrical performance power factor active reactive power Vrms Irms 3 phase voltage or current imbalance frequency total harmonic distortion Page 42 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS 3 5 Selection Guidelines Considerations The following information is required to select the starter appropriately This information is required regardless of whether you are integrating an IPOO soft starter into a custom built enclosure or choosing a complete soft starter panel o
123. deflection of six to nine times that expected under full load conditions O mm cb ull voltage starting also causes a torque transient from zero to locked rotor torque at the instant of contactor osure The instantaneous torque application causes a severe mechanical shock to the motor drive system and the machine The damage resulting from the torque transient is more severe than that due to the maximum torque amplitude SY CTI Current and torque profile for DOL starting Jg Full voltage motor current uat 2 Full voltage motor torque 6 Load torque quadratic load eg pump 7xFLC 6xFLC 5xFLC 4xFLC Current 3xFLC 2xFLC 1xFLC a 10 20 30 40 50 60 70 80 90 100 Speed DOL starter installation Da a Overload relay lt e LO 4 o e Page 10 Medium Voltage Application Guide 710 12280 00A MOOLS Primary resistance starting Primary resistance starters use resistors connected in series with each phase between the isolation contactor and the motor which limit the start current and torque The resistors may be wound cast or liquid resistors Primary resistance starter S K LE LEE The motor current is equal to the line current and the starting torque is reduced by the square of the current reduction ratio The current reduction depends on the ratio of the motor impedance to the sum of the added primary resistance and motor impeda
124. dering the following operating parameters expected start current percentage of motor FLC expected start time seconds expected stop time seconds starts per hour ambient temperature degrees celsius installation altitude metres Expected start current and time can be based on typical requirements for a particular load or can be calculated using a fully engineered solution AuCom uses a purpose designed selection software to select appropriate soft starter models 710 12280 00A Medium Voltage Application Guide Page 43 SOFT STARTERS Medium voltage starter selection software MYS Calculate Max FL Calculo Max FLC MIER Ch ation Parcel m Stars pew xa Sial cmt Andet ieepesahuam 40 Sud We X iude 100 Stop tere r ra mae FLO WA ALS 4020 1790 Power spe 425 ep 13491 A Page 44 Medium Voltage Application Guide 710 12280 00A Switchgear Requirements MVS Panel Options The MVS soft starter is suitable for operating voltages between 2 3 kV 7 2 kV and currents lt 600 A and can be supplied in switchgear panels In all MVS panel options the following LV equipment is standard and is mounted on the LV compartment door e Controller e emergency stop pushbutton e soft starter reset pushbutton E3 panel E3 panel schematic for use with MV motor 2 3 kV 7 2 kV 80 A 600 A Te td OW GOD E RR Soft starter power assembly OI Incoming isolator earth switch R rated li
125. des of the device to determine the difference between the input and output currents individual or 3 phase average If the difference exceeds a preset limit this indicates a phase loss or short circuit fault condition A trip will occur isolating the affected electrical device from the rest of the system Differential Transformer application H HV supply E eB Differential protection device Bi MV motor application gt gt CT1 o Incoming supply Br 8B Differential protection device MV generator application desch CT1 H Output supply Bvee B Differential protection device Bus zone This protection is used on bus distribution systems The 3 phase line currents are measured on all feeders connected to a busbar system The sum of currents entering should equal the sum of currents leaving the busbar system f the difference in individual or 3 phase average currents is not close to zero a trip will occur Bus configurations can be complex but by using the status information of all the switching devices on a busbar system logic within the protection device can selectively isolate the faulty zone 710 12280 00A Medium Voltage Application Guide Page 123 SWITCHGEAR Distance This protection is predominantly used on long transmission lines running between primary substations with radial feeders along the length of the transmission line The dista
126. dium voltage motors Each switchgear arrangement consists of a soft starter panel and a multi start panel for each motor Depending on the system a transition panel may be required and a main incomer panel is optional The entire system is controlled using a PLC mounted in the transition or incomer panel The proprietary PLC logic program provides the end user with flexible motor control options selected via a touch screen Typical arrangement of an MVS multi start system for 2 motors Key features e User interface touch screen e Selectable control options for individual motors e Selectable command source options for individual motors e Motor protection for individual motors e Robu st safety interlocking system e Comprehensive panel indication and bus mimicking 13872 Page 64 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS User interface touch screen The screen provides the user with direct access to all control options PW screen selects between contactor or circuit PW 2 screen selects between soft stop or coast to stop breaker control of individual swrtchgear for individual motors 13870 A 13869 A MIMIC screens emulate switchgear soft starter and M I to M 8 screens select the command source for motor status motor starting and stopping and select between DOL or soft start for each motor separate screen per HII MI START STOP ENABLE START LOCAL REMOTE 1386
127. ducting heatsink face nk size by turning the SCRs off at the end of a start and bypassing the SCR Page 24 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Fans Fans are often used in conjunction with SCR heatsink assemblies to increase the thermal rating of soft starters in arduous conditions eg e applications requiring high start current and or times eg 450 FLC start current for 30 seconds e applications with excessive starts per hour eg 710 starts per hour e installations with excessive operating ambient temperatures eg 45 60 C Busbars Busbars are used to connect the motor and the mains supply to the SCR power assembly Busbars are sized according to the soft starter s maximum current rating For lower current rated soft starters aluminium busbars are common Higher current applications use tinned copper busbars to minimise the cross sectional area There are various methods for connecting conductors to busbars Low current terminations may use small cage clamps High current terminations may use large spreader plates To ensure a good electrical connection when clamping together two conducting faces e clean all conducting surfaces so they are free from oil grease and other contaminants Use an appropriate industrial solvent for best results e lightly buff the mating surfaces of busbars spreader plates cable lugs etc then remove any leftover residue e apply an approved electrical joi
128. e for use in environments with relative humidity between 5 and 95 non condensing Physical Specifications The equipment shall be modular in design and construction The power factor correction components must be installed in a dedicated panel and not the soft starter panel The integrated power factor panel must be enclosed up to IP4X and include e Withdrawable Vacuum fused contactor with ratings 1 Class indoor withdrawable 2 Rated Voltage 12 kV 3 Rated lightning impulse withstand voltage 75 kV peak 4 Rated 1 minute power frequency withstand voltage 28 kV rms 5 Rated Frequency 50 Hz 6 Rated short circuit breaking current 20 kA with fuses 7 Rated short circuit making current 62 5 kA with fuses 8 Duty continuous o Utilisation factor AC6 10 Protection coordination Type 2 11 Minimum Service Life 100 000 operations at full operating current e Inrush reactors designed to reduce the inrush current to that required by IEC60871 1 The supplier must provide calculations for the correct selection of the reactors e Capacitors shall be selected to improve the power factor to the level required by the local utility e The capacitor shall have a voltage rating 20 above the nominal operating voltage so as to be able to withstand high voltages associated with capacitor switching e The capacitor circuit must be supplied from the line side of the soft starter e All panels must provide separate chamb
129. e of the Contractor s personnel who carried out the activity ELECTRICAL SUPPLY Electrical Supply 3 1 General The main power supply to the plant shall be from the power supply authority at XXkV All equipment provided under this Contract shall be suitable for continuous operation at the voltage and conditions noted below Compliance is required to clause 9 101 of IEC 62271 200 Information with enquiries and orders All equipment and work associated with the Contract shall be entirely suitable for operation on the plant power supply systems as specified and tabled below Nominal voltage between phases xxkV Number of Phases 3 System fundamental frequency TBA Hz System Neutral TBA Design Fault Level Xx kA for xx sec Loss of Service Continuity Category TBA Internal Arc Classification TBA 3 2 Standards The work equipment and other items shall comply with the requirements of relevant IEC and other nominated standards codes and regulations including those referenced throughout the Specification and any other Authorities having jurisdiction over any portion of the work and on the method of performing such work Where there is any discrepancy between the referenced standards and this Specification and associated Contract Drawings the requirements of this Specification and associated Contract Drawings shall have precedence 3 24 Switchgear D
130. e rating must be greater than the peak fault current and the break rating must be greater than the short circuit current Upstream network Where Z network short circuit impedance Q S short circuit power MVA U system voltage kV network through to the secondary of the transformer Where Z SC sec network short circuit impedance at the secondary of the transformer network short circuit impedance at the primary of the transforme U t Z sc prim ransformer secondary voltage kV ransformer primary voltage kV The total impedance seen by a short circuit fault at the secondary terminals of the transformer is the sum of the transformer impedance Zu and the short circuit network impedance at the transformer secondary Z U sec E 48 x ae T Zo Transformers Where Zr transformer output short circuit impedance Q Zip transformer impedance 96 LL transformer secondary voltage kV Dun transformer power MVA 710 12280 00A Medium Voltage Application Guide Page 157 SWITCHGEAR Synchronous generator Where Z synchronous machine short circuit impedance Q sc syn Xyn synchronous reactance 76 syn LL synchronous machine output voltage kV syn S synchronous machine output power MVA syn A synchronous machine has three stages of reactance during a short circuit fault The r
131. e start and run characteristics are very important Motors consist of two major components e he stator consists of magnetic poles created from stator windings located in slots within the frame of the motor The full load running characteristics of the motor are determined by the winding configuration and the contour of the stator slots and laminations Motor speed is determined by the number of pole pairs and the supply frequency applied to the stator windings e he rotor consists of a cylindrical short circuited winding embedded within iron laminations The rotor winding is often referred to as a squirrel cage This cage is constructed from a number of bars running parallel to the motor shaft near the surface of the rotor The rotor bars are short circuited at each end of the rotor using shorting rings The material position and shape of the rotor bars determines the starting characteristics of the motor v The rotor design determines the starting characteristics of the motor The stator design determines the AN running characteristics of the motor When 3 phase supply voltage is applied to the stator winding of an induction motor a rotating magnetic field is produced which cuts through the rotor bars The rotating speed of this magnetic field is referred to as synchronous speed Interaction between the rotating magnetic field and the rotor bars induces a voltage which causes current to flow in the rotor bars This rotor
132. eactance is lowest at the beginning of a fault causing the highest level of short circuit current From this level the short circuit current decays to a steady state Subtransient stage This is usually the first few cycles of a fault occurrence The peak short circuit current at this stage determines the fault make rating of a circuit breaker and the mechanical withstand Transient stage This stage typically lasts for 10 to 20 power cycles and determines the thermal withstand and break rating of a circuit breaker Permanent stage This is the short circuit current level until the fault is interrupted by protection and clearing ofthe fault In reality this stage never occurs as the fault is cleared beforehand Stages of a short circurt o a G 8 Wess g LA lien 00 0 0 0 B Subtransient stage Transient stage Permanent stage Current 7 7 ao TD Be LA Ee 13850 A Transient levels for a synchronous generator Subtransient Xd 10 20 1536256 20096 35056 Exposed poles 15 25 25 35 70 20 Transient levels for a synchronous motor Subtransient XE High speed gt 1500 rpm Low speed lt 1500 rpm 00 Asynchronous motors motor output short circuit impedance Q motor input voltage kV motor rated power KW An asynchronous motor will contribute approximately 4 to 6 times its rated current into a short circuit fault
133. ected ambient temperature Manufacturers provide derating factors for high ambient and special mounting configurations Typical nominal current ratings I 1 2 4 6 10 16 20 25 31 5 40 50 63 80 100 125 160 200 250 315 A For a given fuse type and size the maximum possible nominal current reduces as the nominal voltage increases Example For a 12 kV general purpose 442 mm style fuse it is common to have a maximum nominal current rating of 200 A However for the equivalent 7 2 kV fuse the maximum nominal current rating might be 315 A Minimum breaking current A This is the minimum current guaranteed to rupture the fuse and can be obtained from the pre arcing curves or the fuse data sheet This is determined by the overload characteristics of the fuse Depending on the fuse type it can be anywhere from 2 to 4 times the nominal rating of the fuse Overload currents below the minimum breaking current are not guaranteed to rupture the fuse Maximum breaking current kA This is the maximum safe rupturing current determined by the short circuit characteristics of the fuse The maximum breaking current must be higher than the prospective short circuit current at the point of installation The current limiting nature of a fuse means the equipment downstream can have a short circuit withstand rating which is much less than the prospective short circuit current Nominal voltage Un kV This is the rat
134. ection their ability to limit the rms and peak values o immediately downstream at the point of insta tting into fuse bases or bolt style Most fuse types come with the option of a striker pin o activated immediately after the fuse has ruptured The disconnect switch or operate auxiliary contacts tection th f the pros lation Fuse selection depends on the maximum load terminations for busbar fixing r fuse blow pin which is striker pin can directly trip a eir main use is for short circuit One of the major advantages of fuses over circuit breaker protection is pective short circuit current current type of load prospective fault current system voltage and ambient temperature of the installation In a 3 phase installation it is assumed that all three fuses are subjected to the same rate of degradation If one fuse ruptures it is highly recommended that all three be replaced Two categories of fuses are commonly use for medium voltage primary and secondary switchgear installations e General purpose fuses also called E rated fuses by NEMA are typically used in combination with contactors or switch disconnectors e Motor rated fuses also called R rated fuses by NEMA are used for motor feeder circuits and must be used in conjunction with a thermal overload protective device Motor rated fuses have time delayed time current curves and higher minimum melt characteristics to acc
135. ection of parts no ignition of cloths enclosure remains earthed 710 12280 00A Medium Voltage Application Guide Page 71 SWITCHGEAR ANSI defined switchgear ANSI defined switchgear is equivalent to IEC classification LSC2B PM with the following characteristics e the main switching device is withdrawable with disconnecting auxiliary control circuits e separate compartments are provided for voltage transformers and control power transformers e busbar compartments are divided between adjacent enclosures e metal barriers isolate the withdrawable compartment when the main switching device is drawn out into test position e main circuit busbars and connections are covered with fire resistant insulating material e mechanical interlocking prevents stored energy discharge of withdrawable parts e alocking method prevents the withdrawable switching device from being moved into service position e low voltage control parts are segregated from medium voltage apparatus e all voltage transformers must have primary circuit current limiting fuses Switchgear Ratings Switchgear is rated according to IEC 62271 1 When choosing switchgear its rating must be sufficient for the electrical characteristics at the point of installation the environmental conditions it needs to operate under and the safety requirements Future expansion of the switchgear distribution system needs to be considered as this may affect initial rating
136. ed from experience but more precise predictions require analysis of motor and load speed torque curves Successful soft start 7004 T z 1 Full voltage start current 600 200 o 2 Current limit 5004 i zi Full voltage start torque 4004 Z E lt 4 Torque output at current limit 3 3004 L100 z VU E 5 Acceleration torque 200 3e e 6 Load torque 1004 3 en T T T T T T T T T E E 10 20 30 40 50 60 70 80 90 100 8 Speed full speed Unsuccesstul soft start 7004 T S a Full voltage start current 6007 200 S Se 2 Current limit 5004 S Full voltage start torque ao s c 5 4 Torque output at current limit 3 300 4 100 8 M 5 Acceleration torque 2004 3e es Gi Load torque 1004 E 5 E D T T T T T T T T 1 S E T ata 10 20 30 40 50 60 70 80 90 100 Speed full speed Calculating required start current for new or existing AC induction motor installations A number of methods are available to estimate the level of start current a particular machine will require These methods range from generalisations producing approximations through to advanced calculations which yield precise predictions Typical Start Current Estimate Where motor and load start characteristics are unknown and an estimate of typical start current is sufficiently accurate basic application information can allow experienced personnel to estima
137. ed voltage of the fuse and must be greater than or equal to the operating voltage of the system In the case of capacitor applications it is recommended that the fuse s nominal voltage be twice the rated voltage of the capacitor bank Typical nominal voltage ratings U 3 6 72 12 17 5 24 36 kV Selection Cable protection The nominal current rating of the fuse must be equal to or less than the current rating of the cable after cable derating factors have been applied n FUSE l cage The maximum lt total clearing E of the fuse must be less than the A S thermal rating of the cable t rust A S CABLE Switchgear apparatus f a medium voltage fuse is used in combination with a switch disconnector or contactor the nominal current rating of the fuse is determined predominantly by the load However such switching devices have a relatively low maximum breaking current compared with fuses so switchgear manufacturers stipulate a maximum sized fuse which can be used with their switching device Power transformers Fuse manufacturers provide selection tables for the primary input of a medium voltage power transformer These tables consider the transformer s power rating S kVA and nominal primary voltage rating U_prm kV The information may also specify the maximum sized fuse required on the low voltage transformer secondary output for coordination with the primary input fuse fthe manufacturer s selection
138. eed of a motor depends on the supply frequency so controlling the frequency makes it possible to control the speed of the motor A VFD can control the speed of the motor during starting running and stopping Variable frequency drives VFD VFDs generate significant emissions and harmonics and a filter is generally required VFDs are also called variable speed drives VSD or frequency converters VFD motor starting When a VFD starts a motor it initially applies a low frequency and voltage to the motor The starting frequency is typically 2 Hz orless This avoids the high inrush current that occurs when a motor is started DOL The VFD increases the frequency and voltage at a controlled rate to accelerate the load without drawing excessive current e the current on the motor side is in direct proportion to the torque that is generated he voltage on the motor is in direct proportion to the actual speed he voltage on the network side is constant e ct oc cc he current on the network side is in direct proportion to the power drawn by the motor FDs are ideal for applications with an extremely limited supply because the starting current is never more than the motor FLC VFD motor stopping The stopping sequence is the opposite of the starting sequence The frequency and voltage applied to the motor are ramped down at a controlled rate When the frequency approaches zero the motor is shut off A small
139. eeeseeeee eseese teire ee tnetttnttnetnnnrrnnrrnnene e 3 2 2 Physical Gpechflcations nennen 3 S pport ANG aere e T 4 GT Documentation Cep IBI Reis 4 3 2 JEE eet det t t eR tee 4 3 3 Warranty and Repalr neret EE 4 3 4 Standards and Approvals nennen 4 INTRODUCTION Introduction 1 1 Scope This document specifies the minimum requirements for power factor correction when used in conjunction with electronic soft starters This specification is intended as a guideline for suppliers wishing to supply their product to lt customer name gt for their lt project name outline of requirement gt 1 2 Supplier Qualifications The equipment shall have been manufactured by a single vendor The manufacturer shall be certified under ISO9000 The manufacturer shall be able to demonstrate previous successful application of power factor correction with soft starters ENVIRONMENTAL SPECIFICATIONS Environmental Specifications 2 1 2 2 Environmental Specifications The equipment shall be suitable for storage at temperatures from 25 C to 55 C The equipment shall be suitable for use at temperatures from 10 C to 60 C The equipment shall be suitable for use at temperatures up to 40 C without derating The equipment shall be suitable for operation at altitudes up to 1000 m above sea level without derating The equipment shall be suitabl
140. elay M1 F1 K1 CTI a M 6 6 kV MP6s ams So pe FLC 120 A PR 7 S Step Select the contactor e Rated voltage U operating voltage U and AC3 rating 2 motor FLC A 7 2 kV 50 Hz contactor with an AC3 rating of 200 A will be adequate Step 2 Select the fuse e The manufacturer will specify the maximum allowable fuse size As a general rule the nominal rating of the fuse should be 1 5 times the motor FLC In this case lus 1 9 x 120 180 A Use a 200 A fuse e Onatime current curve check that the contactor thermal withstand curve lies outside the total clearing curve of the fuse e From the fuse cut off curve the limited prospective short circuit current of the fuse must be less than the short time withstand current rating of the contactor I fuse lt I contactor Assume the 7 2 kV 50 Hz 200 A contactor has a short time withstand current rating of 8 kA and the prospective rms fault current level at the point of installation is 10 kA 100 EV 50 be 0 Q V 20 5 n oN Ts D apr LATI AFTC e Z iN S 5 e o 5 E 2 E x gt 2 3 1 0 2 5 10 20 50 100 Prospective current kA rms From the fuse cut off curve we can see that a prospective rms fault current of 10 kA l will be limited to 4 kA le by the 200 A fuse Check that fuse lt
141. ending resistance of 1000 daN Wit 15cm Check that the busbars and insulator stand offs are suitable for the installation 14011 A 15cm Step Calculate the forces between the parallel busbars of different phases Assume a short time withstand current rating l of 31 5 kA at 50 Hz ly 2 5 x lk 2 5 x 31 5 78 75 KA F 2x Sxl x10 2 x 80 79 75 x 10 15 2 x 5 33 x 6201 5625 x 0 01 661 09 daN The force between busbars is 661 daN Step 2 Calculate the forces absorbed at the head of each insulator stand off H h x H 15 4 15 F F 661x 661x 1 267 837 27 daN The force to be absorbed by each individual standoff F FxK 837 x1 14 954 18 daN The force imparted on each stand off is 954 daN The imparted force is less than the bending resistance of the insulator stand off 954 lt 1000 daN The insulators are suitable for the application Step 3 Calculate the maximum stress exerted on the busbars According to the selection table the modulus of inertia V for 8 cm x cm end mounted copper busbar pairs is 11 55 cm _Fxl V ES x eeN 12 661x80 1 12 11 55 1 4406 67 x 1155 381 53 daN cm The stress imparted on the busbars is 381 daN cnr The imparted stress is less than the maximum allowable stress for 4 hard copper busbars 381 lt 1200 daN cnr The busbar di
142. ent Ix kA This is the maximum rms symmetrical fault current the device can withstand for a short time period without risk of damage This rating must be higher than the prospective rms fault current at the point of installation Where ERR Ik short time withstand current rating kA Ss L prospective rms fault current kA S 48 U Sic system short circuit power kVA U system operating voltage kV Standard values for 6 3 8 10 12 5 16 20 25 31 5 40 50 63 kA source IEC 62271 1 MV switches tend to have a maximum I of 31 5 A Rated short circuit duration tk s This is the time the device can endure its rated short time withstand current lj without damage This value must be greater than the total expected clearing time of a fault at the point of installation Standard values for t 0 5 2 3 seconds source IEC 62271 1 MV switches tend to have a t rating of second Page 102 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR This is the maximum peak fault current level which the device is able to close make on This rating must be greater than the expected peak let through fault current at the point of installation Rated peak withstand current kA Rated peak withstand current 2 l Where pe Boe Or ae Ue SUE tne asymmetrical peak let through fault current from the first fault 45 ms DC time constant P l
143. ent shall provide at least three additional relays with user selectable functionality enabling indication of e Ready state e Low current state e High current state e Motor temperature state e Trip states with adjustable delays e Motor overload e Current imbalance e Undercurrent e Instantaneous Overcurrent e Mains frequency e Ground fault e Time overcurrent e SCR over temperature e Phase loss e Motor thermistor e Undervoltage 3 5 Programmable Control Inputs The equipment shall provide at least two programmable inputs with the following functionality e Parameter set selection e Auxiliary Trip N O e Auxiliary Trip N C e Local Remote Select e Emergency Mode Operation e Emergency Stop N C Each input must be able to be set for N O or N C operation and must have selectable delays LOGIC CONTROL CONFIGURATION 3 6 3 7 Metering and Performance Monitoring The equipment shall include comprehensive metering and monitoring functions The equipment shall provide real time feedback of operating conditions including e average current e L1 L2 amp L3 currents e average voltage e L1 L2 amp L3 voltages e mains frequency e motor real power consumption kVA e motor active power consumption KW e motor power factor e elapsed running time e time to run before programmed stop when running The equipment shall provide feedback of historical operating information including e lifetime ho
144. er CT is designed to produce a secondary current which is accurately proportional to the primary current lt consists of a single primary winding which an external busbar or cable runs through or it can have a single primary bar brought out to two ends for termination A medium voltage current transformer can have up to three independent secondary winding sets The entire current transformer assembly is encapsulated in resin inside an insulated casing Current transformers are used for metering or protection purposes The accuracy class and size depends on the individual application for example revenue metering would use high accuracy metering CTs NOTE AN Never leave the secondary winding of a CT open circuit This creates extremely high voltages which pose a real danger to personnel Ring style CT DIN style CT 13704 IEC Ratings Rated primary current lpr A The primary current rating of a CT must be greater than the expected maximum operating current it is monitoring e ametering CT s primary current rating should not exceed 1 5 times the maximum operating current e a protection CT s primary current rating needs to be chosen so that the protection pick up level is attained during a fault Standard values for IEC 60044 1 10 12 5 15 20 25 30 40 50 60 75 A and decimal multiples of these values source pr Rated secondary current Isr The secondary current rating of a CT is either A or 5 A CTs
145. er s name equipment model and serial number and certain rating information Many manufacturers also provide additional rating information Rated voltage Ur kV Maximum operating voltage rms the device can continuously withstand during normal operation The rated voltage must be greater than or equal to the system s operating voltage Standard values for U 3 6 7 2 12 17 5 24 36 kV source IEC 62271 1 MV switches tend to have a maximum U of 36 kV Rated lightning impulse withstand rating Up kV This is the peak voltage the device can withstand for a 1 2 50 us standard test wave Standard values for U source IEC 62271 1 EXC Umm 4 e 75 5 ms 170 Rated frequency fr Hz This rating must match the system s operating frequency Rated frequency only has to be marked on the device nameplate if it is not suitable for 50 Hz and 60 Hz operation Rated current Ir A This is the rms level of current which can continuously flow through a device without exceeding its maximum allowable contact temperature rise Temperature rise limits are defined in IEC 62271 1 for an ambient temperature of 40 C The rated current must be greater than the maximum expected load current at the point of installation Standard values for 630 800 1000 1250 1600 2000 2500 3150 4000 A source IEC 62271 1 MV switches tend to have a maximum I of 2500 A Rated short time withstand curr
146. er the complete training programme if required by the customer The training programme shall be delivered at the customer s premises or at the supplier s premises as required by the customer The training programme shall deliver to the customer the skills to e appropriately programme the equipment to meet customer requirements e safely commission the equipment e safely operate the equipment e identify and rectify operating problems caused by incorrect programming e identify and diagnose operating problems caused by faulty equipment Warranty and Repair The supplier shall guarantee the equipment against faults of materials or manufacture workmanship for a period of not less than 18 months from the date of manufacture The supplier shall guarantee to provide servicing support for the equipment for a period of not less than 10 years Standards and Approvals The equipment must as a minimum comply with and be certified to e UL cUL UL508 UL347 e CE EMC EU Directive e C tick EMC Requirements e Marine Lloyds SPECIFICATION MVX Solid State Reduced Voltage Motor Starter MEDIUM VOLTAGE CONTENTS Contents DEVE UCU OIA oT TRE 2 Ti Scopen Du E EE 2 1 2 Supplier Oualtftcattons essen 2 1 3 Starter Ratings 2 1 sh eene d EES 2 Environmental Speclticalloiis oec I IIo eed ee es ee eee 3 2 1 Environmental Specifications seesseeeeeeeeese enee eeneerietnettetnesnen
147. erated Fixed Ma X operate Fixed stored ee operate SCO control uses a single contact This contact is maintained open to trip the circuit breaker and maintained closed to close the circurt breaker DCO control uses two momentary normally open contacts One contact is pulsed closed to trip the circuit breaker The other contact is pulsed closed to close the circuit breaker IEC Ratings Medium voltage circurt breakers must be type tested to provide standard ratings The most commonly used standards for this testing are IEC 62271 1 and IEC 62271 100 The following information provides details of some of the more common ratings which must be marked on the circuit breaker nameplate after type testing Page 90 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Rated voltage Ur kV Maximum operating voltage rms the device can continuously withstand during normal operation The rated voltage must be greater than or equal to the system s operating voltage Standard values for U 3 6 7 2 12 17 5 24 36 kV source IEC 62271 1 Rated lightning impulse withstand rating Up kV This is the peak voltage the device can withstand for a 1 2 50 us standard test wave Standard values for U source IEC 62271 1 SNC ENM o 9 5 5 7 Rated frequency f Hz This rating must match the system s operating frequency Rated frequency only has to be marked on the device nameplate if it i
148. ers for all main sections including Busbars Contactor Capacitors The entire panel including inter chamber must be arc fault certified to 31 5kA for 3 seconds e All panels shall have the following ratings 1 IAC classified AFLR 2 Rated short term withstand current 31 5kA for 3 seconds 3 BIL 75kV SUPPORT AND SERVICES Support and Services 3 1 Documentation The equipment shall be provided with a complete set of user and support documentation including e User manual e Recommended list of spare parts e Schematic amp GA drawings 3 2 Training The equipment supplier shall be capable of providing a complete training schedule with the equipment The equipment supplier shall undertake to deliver the complete training programme if required by the customer The training programme shall be delivered at the customer s premises or at the supplier s premises as required by the customer The training programme shall deliver to the customer the skills to e appropriately programme the equipment to meet customer requirements e safely commission the equipment e safely operate the equipment e identify and rectify operating problems caused by incorrect programming e identify and diagnose operating problems caused by faulty equipment 3 3 Warranty and Repair The supplier shall guarantee the equipment against faults of materials or manufacture workmanship for a period of not less than 18 months from the
149. es the minimum phase to phase and phase to earth busbar clearances e installation s operating frequency NOTE AN The nominal current must be derated for high ambient temperatures usually above 40 C metres The nominal voltage and insulation ratings of a busbar system must be adjusted for altitudes over 1000 710 12280 00A Medium Voltage Application Guide Page 79 SWITCHGEAR Design Busbar system design must consider e adequate minimum required clearance between phases and phase to earth e selection of adequate busbar insulator standoffs e bolting arrangements for continuous busbar connections e thermal effects on busbar and insulator standoffs under normal and fault conditions e electrodynamic forces applied to busbars and insulator standoffs under fault conditions e avoidance of mechanical resonance under normal operating and fault conditions Voltage ratings and clearance IEC 62271 1 gives typical voltage ratings for busbar systems and insulator standoffs Typical voltage ratings and minimum clearances for busbar systems and insulator standoffs Rated voltage Power frequency withstandLightning impulse withstand Clearance recommended P P and P E mm Source derived from IEC 6227 1 Current ratings and dimensions The nominal current rating of a busbar is determined by the type of material shape and cross sectional area of the bar and the maximum permissible temperature rise of the ma
150. esigned to a Switchgear and apparatus IEC62271 1 IEC62271 200 IEC62271 304 GB3906 2006 DL T 404 DL T 593 b Internal arc resistance IEC62271 200 Annex A 6 criteria 1 to 5 C Levels of insulation coordination guide IEC60071 d Degrees of protection IEC60529 e Seismic The Uniform Building code Section 1629 6 8 IEC60721 2 6 Table 1 for static load test f Drilled holes and screw connections for busbars DIN43673 1 9 Classification of groups of environmental parameters IEC60721 3 1 and their severities Storage h Classification of groups of environmental parameters IEC60721 3 2 and their severities Transportation IEC60068 2 32 i Classification of groups of environmental parameters IEC60721 3 3 and their severities Stationary use at weather protected locations ELECTRICAL SUPPLY 3 2 2 3 2 3 3 3 3 3 1 3 3 2 3 4 MV Equipment a Circuit breakers IEC62271 100 b Alternating current disconnectors and earthing IEC62271 102 switches C Contactors IEC60470 d Fuses IEC60282 1 e PFC capacitors IEC60871 1 f Current transformers IEC60044 1 g Voltage transformers IEC60044 2 h Current sensors IEC60044 8 i Voltage sensors IEC60044 7 LV Equipment a LV Switchgear and Controlgear Part 1 General Rules IEC60947 1 b LV Switchgear and Controlgear Part 2 Circuit breakers IEC60947 2 C LV Switchgear and Controlgear Part 5 1 Contro
151. ettable start count e resettable kWh count The control interface shall allow the user to select which parameters to display on the LCD The equipment shall record full details of its state at the time of every protection activation The recorded details shall include at minimum e time and date stamp e protection type e motor operating status e mains frequency e line current e line voltage The equipment s protection log shall store no fewer than eight trips The equipment shall record all changes to its configuration The equipment s change log shall store no fewer than 99 events Remote Communications The starter must have the ability to download parameters and monitor via a computer during commissioning Optional Remote communications be available for the following interfaces to both monitor and control the soft starter e Modbus RTU e Profibus e Devicenet SUPPORT AND SERVICES Support and Services 4 1 4 2 4 3 4 4 4 5 Commissioning The equipment supplier shall be capable of providing commissioning of the equipment Documentation Training The equipment shall be provided with a complete set of user and support documentation including e User manual e Recommended list of spare parts e Schematic amp GA drawings The equipment supplier shall be capable of providing a complete training schedule with the equipment The equipment supplier shall undertake to deliv
152. f bars per phase Shape ratio e a o 008 Oro 012 O14 016 O18 TENERE e RETURN DRE SERE RUNE DNA DEN i6 3 176 18 186 15 15 18 268 270 bare painted e K3 isa function of the mounting arrangement edge mounted one bar base mounted 0 95 multiple bars base mounted 0 75 e K4 is a function of the installed location outdoors indoors enclosed e Kb5isafunction of any artificial ventilation no ventilation ventilation requires validation e K6isa function of the type of current The table below lists the value for K6 for an AC supply 50 Hz and 60 Hz where the separation between busbars is equal to the thickness of each bar Number of bars Page 150 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Exercise Check that the busbar rating per phase is greater than the required e 1 e 1 nominal rating of 2000 A The busbar system is installed in an ES enclosed duct Characteristics two edge mounted bare copper bars per phase Width 8 cm thickness cm spacing cm a 13858 A K Kt K2 K3 K4 K5 K6 1 83 1 1 0 8 1 1 1 464 o 249x 9 8 xS xp vp20x 1 6 20 24 9 90 40 x85 189 1 83 x 1 0 004 x 90 20 24 9x10 87 x2 83 x3 09 41 83x1 28 2366 87 42 34 1 464x 1 464x 1 464x 1 464 x 1546 97 2264 77 A This system is adequate gt Ir
153. g indicators switches pushbuttons LV section panel light Panel anti condensation heaters Motor heater circuit MV LV control supply transformer Voltage transformer or 3 phase Extra CTs for protection or metering LV control transformer Power factor correction requires dedicated panel to install capacitor banks and associated switchgear 710 12280 00A Medium Voltage Application Guide Page 51 SOFT STARTERS AC53 Utilisation Codes The IEC60947 4 2 standard for electronic starters defines AC53a and AC53b Utilisation Categories for detailing a soft starter s current capability AC53a Utilisation Code The AC53a Utilisation Code defines the current rating and standard operating conditions for a non bypassed soft starter The soft starter s current rating determines the maximum motor size it can be used with The soft starter s rating depends on the number of starts per hour the length and current level of the start and the percentage of the operating cycle that the soft starter will be running passing current The soft starter s current rating is only valid when used within the conditions specified in the utilisation code The soft starter may have a higher or lower current rating in different operating conditions 35 A AC 53a 35 15 50 36 ts per hour On load duty cycle WN ES J Lo ime seconds t current multiple of motor full load current ter current rating
154. g qi ertt ceu dn ptu ente eati mete Class A Conducted Radio Frequency Emission 10 kHz to 150 kHz lt 120 69 dB uV 0 15 MHz to 0 5 MHz 79 dB uV Page 36 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS 0 5 MHz to 30 MHz lt 73 dB uV TRENT UE 0 15 MHz to 30 MHz lt 80 50 dB uV m 30 MHz to 100 MHz lt 60 54 dB uV m Radiated Radio Frequency Emission 100 MHz to 2000 MHz lt 54 dB uV m EMC Immunity Electrostatic Discharge 6 kV contact discharge 8 kV air discharge Radio Frequency Electromagnetic Field enn 80 MHz to 1000 MHz 10 V m Fast Transients 5 50 ns main and control circuits ee 2 kV line to earth kV line to line Surges 1 2 50 Us main and control circuits e 2 kV line to earth kV line to line Voltage dip and short time interruption 5000 ms at 0 nominal voltage safe shutdown Standards Approvals CY EMC requirements CE EMC EU Directive Short circuit current with appropriate protection 710 12280 00A Medium Voltage Application Guide Page 37 SOFT STARTERS Power Circuit Configuration with Contactors MVX power circuit with fused main contactor and bypass contactor K2 m qM Ki Tal m A ae UM T e ies wl H ae e M 1 L BE e T8 T3 i e 8 BUS 4 Ut Qs re 1 rra
155. g starting and stopping e ifthe VFD malfunctions the motor can still be started and run DOL via the bypass switch In this case the mains supply must have the capacity to start the motor Control of the bypass switch can be automatic or manual 710 12280 00A Medium Voltage Application Guide Page 7 MOORS Bypassed VFD installation KIA VFD input contactor o Three phase supply a KIB VFD output contactor K1A K1B i E 4 l l l l l l l l l l L 13228 A Operation Motor protection relay e Contactors KIA and KIB close and the motor is run up to full speed Once the output of the VFD reaches main supply frequency contactors KIA and KIB open After a short delay bypass contactor K2 closes e Contactors KIB and K2 are electrically and mechanically interlocked The VF operation by racking out contactors KIA and KIB e Motor protection relay PR protects the motor when K2 is closed D can be isolated from Page 18 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS 3 Soft Starters 3 1 What is a Soft Starter A soft starter is an electronic motor controller used on three phase squirrel cage induction motors During motor starting the soft starter controls the voltage or current supplied to the motor Motor start performance is optimised by reducing the total start current while optimising the torque produced by the motor M
156. ge This is rated at 12 kV Q from 630 A to 2000 A An IAC classification of 31 5 kA for second is achieved by double skin s compartments special locking door designs and top exit arc flaps for pressure release Typical Incomer Feeder Panel H m Jesse OR 00 ls o f a7 K P 5 ze KH fE OR B d i B d up lt pp HET ELO ED ES 8 oo e Front view Side view Rear view SE Circuit breaker withdrawable 4 Voltage transformer fused and withdrawable Page 74 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR A direct incomer panel connects the incoming main supply onto the common horizontal busbar system of a metal enclosed switchgear arrangement without any primary switching device Direct Incomer Panel DIP An earth switch is typically provided at the cable termination end of the circuit for isolation during shutdown and maintenance Access to earth switch operation must be interlocked with the supply end switchgear so that the earth switch cannot be closed onto a live circuit Current and voltage transformers can be supplied as optional items along with a variety of low voltage equipment which is mounted in its own segregated compartment situated at the top front of the enclosure assembly ut AuCom provides an Direct Incomer Panel as part of its L Series switchgear range This is rated at 12 kV Ws
157. ge dip and short time interruption safe shutdown 5000 ms at 0 nominal voltage Standards Approvals CY EMC requirements EMC EU Directive GE Short circuit current with appropriate R rated fuses fitted Excludes contactors and or circuit breakers Page 32 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Power Circuit Configuration MVS power circuit with main contactor bypass contactor main isolator earth switch R Rated fuses and control supply K2 oT E d id MEE NE up eese LX dies b lou I E i o L l Me mg j 2 Eat LI rm ebe M ed i l l C T5 3 4 i P D prom ig E e LH rap I d B l Bl Se E bar 7o 78 7 7 7 7 E c73 110 130 VAC He C74 ELS 220 240 VAC 10 29 l Zi pu T TK 2g 23 LI oba p Sir l LCS l l mu A121 TX o RXo I A M BO CR Se oA oh RX XS TS AB Lt a 44 csi 54 l C r o S cl s i m cali r8 I PU ERN Lo e Ce ced I p l E B10 l A ee 7 ag Bri I ee 4 lt gt ig LESE BE Al Power assembly A4 Controller l 3 Phase 50 60 Hz Supply 5 Remote control inputs QI Main isolator Earth switch C23 C24 Start FI 3 R Rated protection fuses C31 C32 Stop KI Main contactor C4 C42 Reset K2 Bypass contactor C5
158. ge is ikely to occur Auxiliary supply voltage Control supply voltage Typical values are e 10 120 220 230 240 VAC 24 48 VDC 24 250 VAC VDC universal supply perating voltage tolerance 0 15 t range gt 70 50 Derived from IEC 62271 1 and IEC 62271 106 Contactors are primarily selected by their rated voltage U and rated current for a specific utilisation category le Medium voltage contactor utilisation categories Utilisation category Typical application ACI Resistive or slightly inductive loads AC2 Starting and running slip ring motors AC3 Starting and running induction motors AC4 Reversing plugging and inching induction motors AC6b Switching single or back to back capacitor banks Source IEC 6227 1 106 710 12280 00A Medium Voltage Application Guide Page 97 SWITCHGEAR Circuit Design Motor circuit with fuses A contactor always needs some form of back up short circuit protection Although circuit breakers can be used for this purpose itis more common to use MV HRC fuses Fuses have higher fault breaking capacity are very fast acting and are a good current limiting device Consider the following direct on line motor circuit which includes a line contactor short circuit protection fuses and a motor protection relay providing overload protection Assume an operating supply of 6 6 kV 50 Hz and a motor FLC of 120 A Typical DOL circuit with contactor fuses and r
159. gear control and interlocking Protection devices are primarily covered by IEC 60255 1 Protection functions Overcurrent This is the most widely used form of protection In a 3 phase power system all three line currents are measured using current transformers The secondary output of a A or 5 A current transformer is connected to the current input of a protection device Within the protection device analog signals are filtered and sampled before being converted to digital signals for processing A trip condition occurs if a preset current level is exceeded for a specific time There are two basic methods of overcurrent protection e Time overcurrent protection provides overload protection similar to a bimetallic thermal overload device except thermal modelling adjusts the trip curve shape to allow for dynamic heating and cooling conditions If the measured current reaches a point on the overload curve a trip will occur Time overcurrent is also referred to as inverse I protection e Instantaneous overcurrent protection provides medium level and high level short circuit protection Ifa set current level is exceeded for set time period a trip will occur This protection is also referred to as definite minimum time DMT protection Devices may combine time overcurrent and instantaneous overcurrent protection Time overcurrent is normally only applied to electrical machines such as transformers and motors whereas instantaneous
160. he inrush current has a power factor of 0 3 Using the power factor adjustment factor the transformer has a revised Nominal VA rating of 222 VA 200 x 1 11 The next highest standard size would be 250 VA Use a 72 kV 110 VAC 250 VA single phase control supply power transformer gt Transformer primary fuses must withstand the inrush magnetising current which flows when a AN transformer primary is switched on With a medium voltage primary E rated fuses are used and often selected to withstand 25 times the nominal primary current for 0 01 second and 2 times the nominal primary current for 0 1 second 710 12280 00A Medium Voltage Application Guide Page 129 SWITCHGEAR Motor Line Inductors on Soft Starter Applications Long motor cables on the output of a soft starter are seen as a capacitive load which creates a di dt current transient at each SCR turn on event Ifthe current transient repeatedly exceeds the di dt rating of the SCR failure will occur Soft starter start current waveform 15004 10004 500 1000 1500 T r r r r r 55 59 63 67 71 The current transient peak value and rate of rise are are installation dependent and are determined by many factors external to the soft starter The di dt value of the current transient is proportional to the system voltage for example the value for a 6 6 kV system will be approximately twice as much as a 3 3 kV system At a criti
161. he prior consent of AuCom Electronics Ltd AuCom endeavours to ensure that the information contained in this document including images is correct but does not accept any liability for error omission or differences with the finished product Page 4 Medium Voltage Application Guide 710 12280 00A Motors 2 1 Common types of industrial motors Induction motors An induction motor performs two primary functions e start convert electrical energy into mechanical energy in order to overcome the inertia of the load and accelerate to full operating speed e run convert electrical energy into productive work output to a driven load Full voltage starting also referred to as direct on line or across the line starting results in a high starting current equal to locked rotor current The locked rotor current LRC of a motor depends on the motor design and is typically between five and ten times motor full load current FLC A value of six times FLC is common Shaft loading only affects start time not LRC High motor starting currents can cause voltage fluctuations on the electrical supply system and electrical supply authorities often require reduction in motor starting current Reduced voltage starting of an induction motor reduces the available starting torque and loads with demanding start torque requirements may not be compatible with reduced voltage starting When selecting a motor for a specific application both th
162. ial products are constructed to provide a certain level of electrical and mechanical protection against foreign solid objects and the ingress of moisture IEC 60529 and NEMA 250 are the main international standards which rate the level of protection that a product provides Open chassis soft starters Open chassis gear tray style IPOO starters have very little protection from the outside world and must be mounted in a suitable electrical enclosure This style is common with medium voltage soft starters which need to be integrated into an adequately rated switchgear cabinet along with other associated switchgear 710 12280 00A Medium Voltage Application Guide Page 25 SOFT STARTERS Enclosed soft starters Enclosed soft starters have varying levels of electrical and mechanical protection from the outside world Housings are made from a combination of metals alloys and plastics with many different finishes This style is more common amongst low voltage soft starter products In some cases the housing provides enough protection that the soft starter can be wall mounted and does not have to be fitted inside an electrical enclosure Common functionality and features Soft starters vary widely in functionality and choosing the correct product depends mainly on the performance and features required Serviceability and product support are also important factors In fewer cases the main consideration is product cost The most common featu
163. ications The equipment shall have been manufactured by a single vendor The manufacturer shall be certified under ISO9000 The manufacturer shall have produced solid state reduced voltage starters for a minimum of 20 years 1 3 Starter Ratings The ratings of the equipment shall be stated as per IEC 60947 4 2 The supplier must be able to provide documentation confirming that the equipment is correctly rated and fit for purpose ENVIRONMENTAL SPECIFICATIONS Environmental Specifications 2 1 2 2 Environmental Specifications The equipment shall be suitable for storage at temperatures from 25 C to 55 C The equipment shall be suitable for use at temperatures from 10 C to 60 C The equipment shall be suitable for use at temperatures up to 40 C without derating The equipment shall be suitable for operation at altitudes up to 1000 m above sea level without derating The equipment shall be suitable for use in environments with relative humidity between 5 and 95 non condensing Physical Specifications The equipment shall be modular in design and construction The thyristor assembly for each phase shall consist of a discrete module and be individually replaceable Replacement of a thyristor assembly by a qualified service technician shall not take longer than 10 minutes The integrated starter must be enclosed up to IP4X and include e Withdrawable Vacuum fused Line contactor with
164. ide is designed to help engineers in the field of medium voltage select and specify the right MV equipment for their application This guide provides an overview of all the main components in a motor control system in a format that is readily understood by people with limited or no experience with motor control in general and soft starters in particular We hope this document will help e consulting engineers wanting to specify motor control equipment e technical departments using motor control equipment e maintenance engineers at locations with soft starters installed We would welcome your feedback so we can continue to improve this guide The examples and diagrams in this manual are included solely for illustrative purposes The information contained in this manual is subject to change at any time and without prior notice In no event will responsibility or liability be accepted for direct indirect or consequential damages resulting from the use or application of this equipment 2012 AuCom Electronics Ltd All Rights Reserved As AuCom is continuously improving its products it reserves the right to modify or change the specification of its products at any time without notice The text diagrams images and any other literary or artistic works appearing in this document are protected by copyright Users may copy some of the material for their personal reference but may not copy or use material for any other purpose without t
165. ie impedance of feeder cables switchgear busbars etc All switchgear has a short time withstand current rating lj which is typically type tested for 3 seconds t aO Transformer B Switchgear installation Q1 Q2 Q3 Example Transformer power S Secondary rated voltage U Impedance Z Assume infinite power system Rated secondary current Short circuit current Switchgear rating Li 20 MVA I kV 8 To calculate the short time withstand current rating of the downstream switchgear l we must calculate the rated secondary current and the short circuit current of the feeder transformer o S r RS _ 20000 48x11 1050A The transformer rated secondary current is 050 A ks 100 Z 1050x100 _ 105000 8 13125A sc The transformer short circuit current is 13125 A I 2 L 2 13125 A An appropriate switchgear rating is 16 KA 3 seconds Page 144 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR If a load draws more current than the transformer s rated secondary current I load gt I the transformer s output voltage will drop from its rated value U The amount of voltage drop is determined by the internal impedance of the transformer and the level of overload Terminal voltage drop Voltage drop analysis is useful for determining the suitability of a transformer when a
166. ilable external rotor resistance is in the circuit As the motor speed increases the external rotor resistance is reduced by using shorting contactors until all the external resistance is shorted out At this stage the motor has reached full running speed Motor start current is limited by the relatively high impedance of the motor due to the external rotor resistance The major advantage of a slip ring motor is that it produces very high starting torque 150 250 of full load torque from standstill to full running speed while consuming a relatively low level of start current 200 350 of full load current 710 12280 00A Medium Voltage Application Guide Page 7 MORO NS Typical start performance characteristics of a slip ring motor Current 13188 A Speed Speed Slip ring speed control In some cases the variable resistance is used for speed control of the load This method of speed control can cause erratic fluctuations in speed if the load demand changes and heat loss from the resistors causes major inefficiencies Compared with using a slip ring motor for speed control a better result can be achieved by using a variable frequency drive VFD to operate a standard squirrel cage motor A VFD typically provides more precise speed control as well as being more efficient less expensive and easier to install and maintain Provided sufficient start torque is developed with
167. incomer circuit breaker open Q IR 3 Right incomer and bus coupler circuit breakers closed Q IR and Q BC with left incomer circuit breaker open Q IL Typically these interlocking conditions are met using both a mechanical and electrical method Mechanical interlocking Interlocking uses a key system which includes 3 identical locks and 2 identical keys Both incomer and the bus coupler circuit breakers Q IL Q IR Q BC require an interlock key to be inserted into the circuit breaker body and the circuit breaker racked into the service position before the circuit breaker can be closed This interlock key can only be removed when the circuit breaker is open and in the racked out test position When the circuit breaker is in service the interlock key is not accessible Both incomer and the bus coupler circuit breakers O IL Q IR Q BC are fitted with identical locks but only two matching keys are available Under normal operating conditions the two incomer circuit breakers are closed using the two available interlock keys The bus coupler circuit breaker is not permitted to close If one of the incomer supplies is lost the associated circuit breaker is opened and racked out to the test position The interlock key can be moved to the bus coupler circuit breaker allowing it to be racked into the service position and closed When normal supply resumes the bus coupler circuit breaker has to be opened before the revived incomer circ
168. ings for circuit breakers based on the following conditions Rated capacitive switching currents rated cable charge breaking current A bb rated single capacitor bank breaking current A bb rated back to back capacitor bank breaking current A bi rated back to back capacitor bank inrush making current kA NOTE AN These ratings are recommendations only Individual circuit breaker ratings may specify different values Preferred values of rated capacitive switching currents Rated voltage Rated cable charging Rated single capacitor Rated back to back Rated back to back breaking current bank breaking current capacitor bank capacitor bank inrush breaking current making current Ur kV rms ly A rms Derived from IEC 62771 100 IEC Classifications Medium voltage circuit breakers can be type tested and categorised according to the classifications in IEC 62271 100 Classifications of switching devices S extended electrical endurance designed so no maintenance of circuit interrupting parts is required during the expected operating life extended mechanical endurance 10000 operations intended for use on cable systems intended for use on overhead line systems Source IEC 62271 100 standard mechanical endurance 2000 operations 710 12280 00A Medium Voltage Application Guide Page 95 SWITCHGEAR Medium Voltage Contactors Contactors are a 3 pole load bre
169. ircuit power VA Single command operated Soft starter CP IP ransmission control protocol Internet protocol S VFD ransient recovery voltage Ambient temperature Rated short time withstand duration s Stopping time s Starting time s Nominal voltage kV Power frequency withstand voltage KV rms for minute Rated voltage kV Lightning impulse withstand voltage kV peak for 1 2 50us Variable frequency drive Page 220 Medium Voltage Application Guide 710 12280 00A 7 References ABB 2000 MWD Surge Arrestors CHHOS AR 3209 00E ABB 2006 ABB Switchgear Manual Ith Edition http www02 abb com global seitp seitp 6 nsf O bf 43 b2c459e7a3cl1256f5d004a29bb Sfile index abb en html ABB 2007 Fuses Catalogue 3405PLO04 W en ASTM 2002 Standard specification for standard nominal diameters and cross sectional areas of AWG sizes of solid round wires used as electrical condu EC 2005 General EC 2007 EC 201 transformers EC 2007 EC 2008 IEC 6227 1 100 High vol EC 201 1 IEC 62271 102 High vo and earthing switches EC 2011 IEC 62271 106 High vo EC 201 I IEC 62271 200 High vol controlgear for rated voltages above contactor based controllers and mot ctors BIPM International Bureau of Weights and Measures http bipm org opper Development Associati
170. is installation is acceptable abe Page 140 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Calculations peak inrush current for multiple capacitor banks To calculate the peak inrush current l of a number of capacitor banks with extra inrush reactance x E e C1 C2 C3 C4 capacitor banks Cl C2 C3 C4 are each rated for 900 kVAr at 7 2 kV inrush reactance LI L2 L3 L4 are each rated at 40 uH Step Calculate the re rated capacitor bank power Q at system voltage U Q re rated capacitor bank power at required system voltage kVAr Q capacitor bank power at manufacturer s specified nominal voltage kVAr U system voltage U capacitor bank nominal voltage Q uy Q LL U 2 Q Q ta Up 2 amp w S2 7 2 900x0 766 7689 kVAr The re rated power at 6 3 kV is 689 kVAr Step 2 Calculate the individual capacitance of each power bank C capacitance uF Q capacitor bank power kVAr U system voltage kV f system frequency Hz ONES EPOR TIN F 2550 689 70 6 C mie 1000 689 85 69 x 314 16 1000 _ 689 apes gi 1000 55 26 UF The capacitance of each bank is 55 uf 710 12280 00A Medium Voltage Application Guide Page 141 SWITCHGEAR Step 3 Calculate the equivalent capacitance of banks which are switched in C Dan 204040 55 55 55 165 uF The equivalent capacitance Is 165 uf Step 4 Calculate the
171. is selected using two rotary switches on the interface The interface automatically detects the data rate e he GSD installation file is available from the AuCom website For more information on using the Profibus Interface refer to the Profibus Interface instructions ou J B UJS Tested and certified by Profibus Page 40 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS DeviceNet Interface MVS and MVX soft starters can connect to a DeviceNet network using the DeviceNet Interface Rp 49 i5 Standard 5 wire connection onto a wu EN BENIN DeviceNet network 120 Q termination PE resistors are required at each end of the y pu CN oi network cable E BK A e The Devicenet Interface is powered from the network e Each soft starter requires a separate DeviceNet Interface e A DeviceNet network can support up to 63 DeviceNet Interfaces as slaves e The DeviceNet node address MAC ID and data rate are selected using three rotary switches on the interface e he EDS installation file is available from the AuCom website For more information on using the DeviceNet Interface refer to the DeviceNet Interface instructions Ethernet options Industrial plant automation is rapidly moving towards Ethernet based protocols Ethernet is a real time high speed technology which provides a seamless and unified system linking information from the factory and plan
172. ith minimum amount of labour All relays except where otherwise stated shall be capable of breaking or making the max current which can occur in the circuit which they have to control and they shall not be affected by vibration or by external magnetic fields Permanent facilities shall be provided for testing protective equipment in situ without having to remove any connecting wires Current amp Voltage Transformers 1 The switchgear panels shall be provided with current and voltage transformers to the specifications provided or shown on the drawings having ratios and quantity as shown in the drawings Only voltage transformers with proven reliability shall be used In general voltage transformers shall be of epoxy resin encapsulated type to the requirements of IEC 60044 2 The primary windings shall be connected to the switchgear through readily accessible renewable high rupturing capacity fuses of approved type Secondary fuses or MCB s shall be provided for each transformer and the secondary windings shall be earthed at one point ELECTRICAL SUPPLY All current transformers C Ts shall be of the epoxy resin encapsulated type and shall conform to the requirements of IEC 60044 1 for the type of duty required The CT s shall be installed on the side of the circuit breaker remote from the busbars The primary winding shall be of the bar type and of approved cross section compatible with the circuit breaker rating
173. l circuit 1EC60947 5 1 devices etc d LV Switchgear and Controlgear Part 7 1 Auxiliary IEC60947 7 1 equipment terminal blocks Service Conditions All equipment provided under this Contract shall be suitable for operation and standby duties for the nominated operating conditions under the following service and climatic conditions Climate TBA Ambient air temperature minimum 5 C maximum 60 TC derate above 40 Altitude 1000 m above mean sea level Relative humidity minimum 35 maximum 95 Atmosphere TBA Seismic Zone TBA Ventilation and thermostatically controlled heaters shall be provided where necessary to prevent condensation of moisture on idle or stored materials and equipment Ventilation shall be provided to dissipate heat from heat producing electrical equipment and keep them and other materials and equipment in the affected area within the safe temperature limits recommended by the respective manufacturers Corrosion Protection All equipment provided shall be painted or protected against nominated corrosive environments The Contractor Supplier to specify the coating system provided Anti corrosive paint to a minimum thickness of 50 micron shall be applied to the cleaned metal surface The finish shall be resistant to the harmful effects of the specified environment Enclosure Protection Unless otherwise specified or shown on the Drawings all electrical control
174. l current of a 500 kVAr power factor bank operating on a 6 6 kV 50 Hz supply system _ Q C ent x1000 500 6642150 000 500 43 56 x 314 16 36 uF The capacitance is 36 uF _ Q nom 48 xU x1000 The nominal current is 44 A Capacitor peak inrush current When a capacitor bank is initially switched on a large inrush current flows for several cycles before settling down to a steady nominal current value The peak value and duration of the inrush current is determined by e system voltage U e system short circuit power S e capacitor bank power Q e number of back to back capacitor banks feeding back into the system The values of peak inrush current and oscillation frequencies are typically in the order of a few kA at some 100 Hz for a single capacitor bank and a few 10 kA at some 100 kHz for multiple back to back capacitor banks Voltage switching transients Capacitor bank switching produces oscillating voltage transients which are reflected back onto the network supply The severity of this phenomenon can be lessened by reducing the capacitor bank peak inrush current Capacitor bank switching transients Us aO Network voltage a B Capacitor voltage Capacitor current i frre E 13810 A Page 138 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR IEC 6087 1 specifies that the peak inrush current of a capacitor bank must not exceed 100 times its rated nominal current
175. l speed the soft starter SST is bypassed using circuit breaker Q20 Reverse control sequence Before starting in reverse both the supply side earth switch Q3 and the motor side earth switch Q30 must be open and mains supply must be present l 2 3 The reverse direction circuit breaker Q2 is closed Electrical interlocking disables the forward direction circuit breaker O from closing The soft starter is given a start command and the main circuit breaker QIO closes The soft starter performs a series of prestart checks then starts the motor in the reverse direction Once the motor has reached full speed the soft starter SST is bypassed using circuit breaker Q20 Page 60 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Multi motor s tarting This standard method of starting several medium voltage motors is often found in the water and mining industries Most multi start control systems have 2 4 motors of the same kW size Each motor is started and stopped from the output of an electronic motor starter The starter is usually a soft starter SST providing the utility system has the capacity to supply the maximum required current without any significant disturbance A guideline for maximum required current is 4 n x motor FLC where n total number of motors in the system H supply capacity is limited a variable frequency drive VFD may be used instead of a soft starter Once a
176. l styles We also offer a range of metal enclosed switchgear panels rated up to 36 kV and 2500 A covering all standard industrial configurations e Incomer feeder panel e Direct incomer panel e Buscoupler panel e Bus riser panel e Metering pane e Direct on line motor starting panel e Power factor correction panel e Transition termination panel Metal enclosed medium voltage switchgear panels and associated apparatus rated from kV to 52 kV are covered by IEC 62271 200 this standard supersedes IEC 60298 Panel design and construction is determined by several key operating factors and classifications e Rated voltage U kV Determines the minimum insulation level requirements e Rated current I A e Rated frequency f Hz e Short circuit power Sec MVA Determines elements of mechanical panel design and selection of integrated switchgear apparatus e Accessibility to panel compartments e Continuation of service with main compartment open e Necessary isolation and segregation of live parts e level of internal arc withstand 710 12280 00A Medium Voltage Application Guide Page 69 SWITCHGEAR 4 1 Switchgear Classifications There are many different types of enclosure designs for medium voltage switchgear use However the most commonly accepted and used style is metal enclosed with segregated and insulated apparatus compartments AuCom s MVX soft starter range and medium voltage distribution range
177. lates iary labels VT fuses fitted in fixed VTs LJ Test sheets VCB a Earth switch aux Test sheets withdrawable VT Test sheets fixed VT Solenoid for earth switch interlock use N A if not fitted Solenoid on cable compartment door use N A if not fitted Programming reay J Too KEEN D se an feel Vottage test on withdrawable Vs ll Bushings for holes between cubicles EO E Drawings as built information eS See eee nter cubicle cabling marked and ready for To be done on site termination 710 12280 00A Medium Voltage Application Guide Page 163 SWITCHGEAR Commissioning Tools and Equipment Typical Crimp tool for VCB socket Terminal screwdriver for LV terminals Ferrule crimp tool Pin punch removing sockets VCB plug Multimeter Insulation tester Torch Scotch pad De burring tool Wedges for cubicle alignment Plumb bob and string Appropriate spanner and or socket set Appropriate allen key set Appropriate screwdriver set Torque wrench Commissioning sheets Spare parts As built electrical and mechanical drawings Page 164 Medium Voltage Application Guide 710 12280 00A 4 7 Switchgear Related IEC Standards IEC Standard Title Supersedes old Number standards 6004 1 Instrument transformers Curetwamfomes fO y 6004 8 Instrument transformers Electronic current transformers 0060 1 High voltage
178. line fuses R rated Refer to the MVS section for details of optional panel equipment The panel can be supplied in a stand alone format or with rear horizontal busbars for an MCC switchgear line up Typical MVS E3 panel Q1 Els T UA L1 eo nyw S 14049 A LOE Mains supply FI 3 MV protection fuses pee MVS soft starter OI Isolator earth switch Page 178 Medium Voltage Application Guide 710 12280 00A SCHEMATIC DIAGRAMS The standard E2 panel option consists of a main and bypass contactor A means of isolation and earthing as well as some form of line protection must be supplied and installed separately upstream of the E2 panel Refer to the MVS section for details of optional panel equipment E2 panel option Typical MVS E2 panel 14050 A Oo Mains supply MVS soft starter reas 710 12280 00A Medium Voltage Application Guide Page 179 SCHEMATIC DIAGRAMS 5 6 MVX Schematic Diagrams The MVX medium voltage soft starter is rated up to 200 A at kV AuCom supplies the soft starter in an IP4X metal clad style panel with two switchgear configurations These are referred to as the contactor or circuit breaker panel options Contactor panel option This panel option is limited by the contactor fuse rating to a maximum motor FLC of 160 A It consists of a withdrawable fused cont
179. ltage Suitable operating range Power frequency withstand Lightning impulse withstand voltage voltage e kV kV rms rer minute kV peak 1 2 50 us Source IEC 6227 Rated frequency f Hz This rating must match the system s operating frequency Standard frequencies are 50 Hz and 60 Hz ur Xy A 50 Hz CT can be used on a 60 Hz system but a 60 Hz CT cannot be used on a 50 Hz system ux S Rated real output power VA The maximum power a CT secondary can deliver to guarantee its accuracy and performance The total sum VA including cable connectors and load must not exceed the rated real output power of the CT Standard values are 2 5 5 10 15 VA e Cable burden Where VA ca cb k 0 44 for 5 A secondary 0 0176 for A secondary D S L total feed return length of cable metres S cross sectional area of copper cable mm e Metering instrument burden Metering instrument digital VA approx Metering instrument electromagnetic or induction 3 VA approx Transducer self powered 3 VA approx e Protection instrument burden Protection instrument digital VA approx Protection instrument electromagnetic overcurrent 3 10 VA approx 710 12280 00A Medium Voltage Application Guide Page SWITCHGEAR Exercises A CT with a A secondary is connected to an electromagnetic ammeter located 10 metres away using 2 5 mm copper
180. ly when the circuit breaker is in the open and isolated position by means of a mechanical interlocking system The earthing device shall have sufficient capacity to withstand full fault level at the point of installation Provisions shall be provided for prominent indication when any of the earthing devices has been activated The cross sectional area and construction of the earthing busbar shall be capable of withstanding the full rated short circuit current of the switchgear for 3 seconds Cable Termination 1 2 3 Power cable terminating compartment shall be suitable for reception of the specified cable type number of cables and direction of entry Upon completion the cable termination compartment shall be sealed by approved method to prevent ingress of rodents and insects Entry into the control cable ducts for multi core PVC SWA PVC cables shall be provided and shall be in a readily accessible position in each switchgear panel Protection Relays 1 2 3 Electronic protection relays providing functions as stated in the Drawings are preferred All relays shall confirm to the relevant IEC standards or approved equivalent All relays shall be contained in dust proof cases All cases shall be earthed unless otherwise stated The relays shall be mounted on the switchgear panel in a balanced and approved arrangement They shall be of flush mounted type and shall be arranged so that replacements can be effected quickly and w
181. maximum peak fault current kA lk short time withstand current kA Forces on insulator stand offs Insulator stand offs must also withstand the forces imparted on the parallel busbars during a short circuit fault Uh Where Pak H F force absorbed by head of insulator stand off daN F force on busbar centre of gravity daN The force absorbed at the head of each insulator stand off is derived using a multiplication factor K according to the total number of evenly spaced insulator stand offs per phase Multiplication factor K uberi sand Mutpcation factor K 35 5 CC The absorbed force per insulator stand off daN is F FxK The bending resistance of an individual insulator stand off must be greater than the calculated absorbed force F 710 12280 00A Medium Voltage Application Guide Page 153 SWITCHGEAR Mechanical strength of busbars The maximum allowable stress which a busbar can absorb n is determined by the busbar material ExL V Where I2 a distance between insulator stand offs on the same phase cm VI inverse modulus of inertia for bars of the same phase cm Maximum allowable values for n for different busbar materials Maximum s sen Copper A hard 1200 Copper hard 2300 Copper 4 4 hard 3000 200 Moment of inertia 1 and modulus of inertia VV of busbars
182. mensions and material are suitable for the application 710 12280 00A Medium Voltage Application Guide Page 155 SWITCHGEAR Resonant frequency The busbar system must be designed to avoid resonance at the nominal system frequency and twice this value The calculations should include some tolerance Where f resonant frequency Hz E modulus of elasticity copper 1 3 x 10 daN cm f 112 EL aluminium 0 67 x 10 daN cm mod m linear mass of busbar daN cm moment of inertia of the busbar cross section relative to the perpendicular vibrating plane er l distance between insulator stand offs of the same phase cm Exercise Verify the resonant frequency of the busbar system in the Exercise above ExI mx 4 1 3 10 x 17 33 0 071x 80 22529000 2908160 112V7 75 112x 2 78 311 36 Hz f 112 112 112 The resonant frequency is well away from 50 Hz and 100 Hz The busbar solution is suitable Short Circuit Calculations Short circuit fault currents at different points on a system are determined by the power feeding into the fault and the equivalent short circuit impedance seen by the fault Power sources feeding a fault include supply networks transformers generators and motors Impedance is a vital factor in limiting the level of short circuit current Sources of impedance include all electrical machines as well as cables overhead lines busba
183. motor has reached full running speed it is fed directly from an input bus In this mode of operation some form of motor protection is required for each motor A master contro ler is required to control and supervise the entire multi start system This can be a PLC or an integrated part of the starter There are typical e In Auto y two modes of operation mode the start and stop sequence can be preselected and the master controller handles the entire switchin e n Manu g procedure al mode the starter is disabled and DOL control of each motor is provided by manual switching of each motor bypass circuit breaker or contactor The entire system relies on critical time switching of circuit breakers or contactors which are usually fixed switching devices Withdrawable switching devices are often used on the starter input and output to provide physical isolation This allows the starter s input and output to be isolated for servicing in the event of a fault NOTE The fo availab llowing example shows a typical configuration There are many different control methods le for multi motor starting systems 710 12280 00A Medium Voltage Application Guide Page 6l SOFT STARTERS Typical multi start system with 3 motors For clarity current transformers and motor protection relays are not shown
184. n Torque Over Speed Range n Speed Range n Speed Range n Speed Range n Speed Range n Speed Rangen MA 95 FLT secs FLT secs 96 FLT secs 96 FLT secs 96 FLT secs 0 10 8 4 1 50 5 8 2 40 ae 10 53 38 3 35 97 1 31 10 20 1 5 8 59 1 7 7 58 SU 2 22 10 6 1 19 16 4 0 77 20 30 0 0 283 04 3 2 3 96 72 EE 12 2 1 04 18 0 0 70 30 40 23 5 45 0 9 13 49 5 1 2 47 10 2 1 23 16 3 0 78 40 50 ER 2 78 St 11 78 34 3 73 88 1 43 15 3 0 83 50 60 Ee 1 75 3 5 3 65 1 3 9 39 12 1 75 142 0 89 60 70 11 2 1 13 7 1 1 78 1 8 7 09 47 2 69 12 3 1 02 70 80 14 7 0 86 9 8 1 28 3 6 3 53 4 1 3 08 132 0 96 80 90 17 6 0 72 10 6 1 19 1 6 7 70 93 136 222 0 57 90 10095 11 8 1 07 1 9 6 62 10 8 im 263 0 48 447 0 28 259 secs 4 secs 8 secs 18 secs 8 secs 4 0x FLC 4 5x FLC 5 0 x FLC 5 5 x FLC 6 0 X FLC n FLT secs FLT secs FLT secs FLT secs FLT secs 0 10 16 4 0 77 24 1 0 52 32 7 0 39 42 0 0 30 42 0 0 30 10 20 23 2 0 55 30 8 0 41 39 3 0 32 48 0 0 26 48 0 0 26 20 30 24 8 0 51 32 4 0 39 40 9 0 31 49 0 0 26 49 0 0 26 30 40 23 2 0 54 31 1 0 41 40 0 0 32 47 5 0 27 47 5 0 27 40 50 227 0 56 31 1 0 41 40 6 0 31 475 0 27 475 0 27 50 60 22 2 0 57 31 2 0 40 414 0 31 475 0 27 475 0 27 60 70 21 2 0 60 31 2 0 40 42 4 0 30 475 0 27 475 0 27 E 70 80 23 6 0 53 35 5 0 36 48 7 0 26 51 0 0 25 51 0 0 25 80 90 37 1 0 34 54 0 0 23 67 0 0 19 67 0 0 19 67 0 0 19 2 90
185. n Guide 710 12280 00A SWITCHGEAR Withdrawable circuit breaker The withdrawable circuit breaker provides load switching short circuit protection and circuit isolation when opened and in the draw out position The cable side earth switch is interlocked with the circuit breaker and can only be closed when the circuit breaker is in the drawn out position A protection device is required to provide overload and short circuit protection The withdrawable contactor with integrated fuses provides load switching and circuit isolation when opened and in the draw out position The fuses provide short circuit protection The cable side earth switch is interlocked with the contactor and can only be closed when the contactor is in the drawn out position isconnector The gas insulated rotary disconnector has three physical operating positions It provides load switching in the ON position isolation in the OFF position and earthing in the EARTH position Short circuit protection is provided by fuses but a fixed type circuit breaker could be used instead 710 12280 00A Medium Voltage Application Guide Page 101 SWITCHGEAR IEC Ratings Disconnectors and earth switches are type tested to specific IEC standards IEC 62271 1 provides standard ratings and IEC 62271 102 details test methods and specific requirements for medium voltage disconnectors and earth switches The nameplate label must show the manufactur
186. n the linear part of the CT secondary current curve Ifa CT saturates before the relay trip level is reached the fault will remain undetected leading to equipment damage and serious danger to personnel Protection class CT The most commonly used protection class is a 5PX where X is the accuracy limit factor ALF or multiplication factor of the rated primary current The secondary current is 1 accurate at rated primary current and 5 accurate at X times rated primary current Typical protection class CT ratings are 5P10 5P15 5P20 Operating range for protection class current transformer Ja Saturation Linear operating range at accuracy class tolerance Ideal protection setting trip zone 50 100 ALF Flux E a A E 100 ALF 13701A Lg Example A 200 1 A CT has a protection class rating of 5P15 The secondary current is guaranteed to be linear up to 5 times the rated primary current The secondary current will be A 1 at 200 A primary current and 15 A 5 at 3000 A primary current For guaranteed operation any overcurrent trip setting should be between 7 5 15 A secondary current Selection The main considerations for selecting a CT are the primary and secondary current ratio real output power rating VA and accuracy class Secondary selection considerations are rated primary voltage frequency and thermal short time withstand current Primary and secondary current ratio
187. nce As the motor accelerates the stator impedance increases resulting in increasing stator voltage with speed Once the motor reaches full speed the resistors are bridged by a second contactor to supply full voltage to the motor The initial start voltage is determined by the value of the resistors used If the resistors are too high in value there will be insufficient torque to accelerate the motor to full speed so the step to full voltage will result in a high current and torque step The reduced voltage start time is controlled by a preset timer which must be correctly set for the application If the time is too short the motor will not reach full speed before the resistors are bridged Excessive start time results in unnecessary motor and resistor heating Several stages of resistance can be used and bridged in steps to control the current and torque more accurately This minimises the magnitude of the current and torque steps Primary resistance starters dissipate a lot of energy during start due to the high current through and the high voltage across the resistors For extended times or frequent starts the resistors are physically large and must be well ventilated Primary resistance starters are closed transition starters so they are not subject to reclose transients 710 12280 00A Medium Voltage Application Guide Page MOORS Start performance characteristics ofa correctly selected primary resist
188. nce to a fault is determined by calculating the impedance with a healthy line impedance Both line voltages and currents are measured to calculate the impedance line fault fault Selective line isolation is achieved by setting a trip zone within the protection device This trip zone covers a specific distance along the length of the transmission line from where the protection device is installed Protection devices are used in pairs installed at each end of a transmission line and a fast speed real time communication link is between devices Distance protection system 13754 A 0 3 2 Radial feeders B Communication link Voltage required D Distance protection device K 7 Voltage protection is often used on transformers motor generators and power factor banks which can be damaged due to long term undervoltage or overvoltage conditions If the average 3 phase or any individual line voltage falls outside a specific range for a specific period a trip will occur A time delay is used to override temporary surges and dips in the mains voltage Page 124 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR ANSI protection codes The American National Standards Institute developed a standardised table of numerical codes indicating specific protection functions These codes are internationally recognised and are often used in single line diagrams or tender documents as part of a proje
189. ndoor or outdoor some protection from windblown dust rain splashing P 66 water hose directed water and ice 4X ndoor or outdoor some protection from corrosion windblown dust P 66 rain splashing water hose directed water and ice 6 ndoor or outdoor some protection from ice hose directed water entry P67 of water when submerged at limited depth 12 ndoor protection from dust falling dirt and dripping non corrosive P 54 iquids 13 ndoor protection from dust spraying water oil and non corrosive liquids P 54 NOTE NEMA and IP ratings are not directly equivalent and this information provides an approximate correlation only 710 12280 00A Medium Voltage Application Guide Page 171 SCHEMATIC DIAGRAMS 5 Schematic Diagrams 5 1 Electrical Symbols Common Switching Functions The following table shows the standard IEC and ANSI symbols for common switching functions y IEC 60617 2 is a European standard ANSI Y32 2 is a North American standard As a general rule 9 countries using a 50 Hz supply normally adhere to IEC standards and countries using a 60 Hz supply E normally adhere to AINSI standards Designation and Symbol ANSI Function Switches operating Switches fault symbol IEC current current E CE NEM EN Earthing disconnector EP T Earths short circuit making Switch Switches o Sw EE Ces ET MERENN Fixed circuit breaker p Switches and protects x o o Withdrawable circuit Swi
190. ne fuses Q1 F1 3 Bypass contactor E2 panel E2 panel schematic for use with MV motor 2 3 kV 7 2 kV 80 A 600 A Soft starter power assembly Bypass contactor Short circuit line protection is provided externally using R rated fuses or an MV circuit breaker 710 12280 00A Medium Voltage Application Guide Page 45 SOFT STARTERS Fanel physical layout iP a 14078 B Front view Side view Control components mounted on the LV compartment door 0 B Front view of a typical MVS starter panel 2 Controller 3 Emergency stop pushbutton Main isolator earth switch O1 R rated protection fuses F1 3 Main contactor K1 Bypass contactor K2 Power assembly A1 nput terminals LI L2 L3 Rear cable compartment oJ NISI A wj rN Output terminals TII T2 T3 Reset pushbutton Page 46 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS MVX panel option Soft starters such as the MVX are rated for a maximum operating voltage U of I I kV The MVX is available as an IPOO unit or an indoor style metal enclosed switchgear panel with a rated voltage U of 12 kV and an arc proof classification of 31 5 kA for second For operating currents FLC gt 60A circuit breakers are required For operating currents lt 60A the switching device can be either contactors
191. ng adjustable protection functions included as standard ANSI Codes The equipment s sensitivity and response for protection functions shall be programmable gt Overload 49 51 Undercurrent 37 Instantaneous Over current 50 Current Imbalance 46 Frequency 81 Auxiliary Trip A 86 97 Auxiliary Trip B 86 97 Excess start time 66 Maximum start Time 48 Starter Communications Failure 3 Battery Clock Failure 3 SCR Temperature Ground Fault 50G Overvoltage 59 Under voltage 27 Phase sequence 47 Phase Loss 47 Power Loss 32 VVV VV VV VV VV VV VV WV v The following protection states are also provided e Motor not detected e Auxiliary trip A e Auxiliary trip B e Network communications e EEPROM failure e Gate drive failure e Conduction 1 invalid e Conduction 2 invalid e Conduction 3 invalid LOGIC CONTROL CONFIGURATION e Assembly control voltage low The equipment s possible responses to protection activation shall include at minimum e trip cease operation and disable the motor e warn notify the condition to the operator and continue operating e ride through write the event to memory 3 4 Programmable Relay Outputs The equipment shall provide output relays to control operation of e main contactor e bypass contactor e power factor correction capacitor bank The equipment shall provide an output relay to indicate that the unit is operating The equipm
192. nting compound to all mating surfaces e use the correct type and size of fasteners and tighten to the specified torque e insulate bare exposed electrical joints according to local electrical regulations Current sensors Soft starters which control motor start current or provide a motor protection function will have some form of current sensing on the controlled phases If only two phases are monitored the current in the third phase is normally surmised using vector calculation Current transformers are widely used but other forms of current sensing are becoming mode widely used PCBs Compact printed circuit boards are used to mount all the necessary electronic firmware such as e digital microprocessors for I O function SCR firing control motor protection function communications etc e SCR firing circuits e current sensing input circuits necessary for certain soft starter types e metering circuits e user interface e digital and analog input and output circuits e terminals for customer interfacing e communication port options Some soft starter manufacturers have protective conformal coating as an option Conformal coating protects PCBs from moisture and general dust and grime In aggressive gaseous and chemical environments the soft starter should be installed in a suitable totally sealed enclosure DARE AN amp Conformal coating is standard on all AuCom soft starters Housing Industr
193. ny resistive loading 2 Findthe corresponding transformer power rating in the Nominal VA rating column 3 Check that the Nominal VA rating value is larger than the calculated total sealed VA of the transformer secondary load 4 If the inrush VA power factor is different from 0 4 multiply the Nominal VA rating by the Power Factor Adjustment factor Page 128 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR CPT selection Inrush VA at selected voltage drop Inrush VA Nominal VA rating 85 voltage drop 90 voltage drop 95 voltage drop 347 38 m CPT selection power factor adjustment factor GE o1 9 o3 4 os os 97 98 9 19 Adusment er RER 125 111 109 091 982 ove 07 067 964 Exercise A transformer with its primary connected to 7 2 kV has a 10 VAC secondary with a total inrush loading of 850 VA and a resistive load of 100 VA The total sealed VA of the load is 200 VA A voltage drop of 85 is acceptable during the inrush stage The power factor of the inrush current is 0 3 Calculate the necessary power rating of the control supply power transformer The total inrush loading is 950 VA 850 VA 100 VA The next highest Inrush VA figure in the 85 volt drop column is 1267 VA 2 An Inrush VA of 1267 VA equates to a Nominal VA rating of 200 VA 3 200 VA seems acceptable as this is equivalent to the total sealed load VA 4 T
194. of each individual pole are externally connected in star configuration Each end of the secondary winding is brought out to a customer termination box The secondary windings can be externally connected in star or delta configuration and must always be separately fused Star connection of the secondary winding is preferable as this provides voltage stability through solid earthing of the neutral point and 3 phase and neutral is available for voltage measurement Switchgear installations use either fixed or withdrawable voltage transformers Withdrawable voltage transformers are mounted on a draw out truck arrangement The power rating and accuracy of a transformer arrangement will depend on its application For metering protection and indication power ratings are small with accuracies in the range of 0 5 3 0 A voltage transformer used to provide a control supply may have a power rating above 5 kVA In this case accuracy is not as important Relevant standards IEC 61869 3 IEEE C57 13 Voltage transformer 3 phase fixed Control supply transformer single phase fixed L1 L2 L3 L1 L2 L3 3 3 kV 110 VAC 4 2 WA 99 Q V Mains supply Mains supply 2 3 x single phase VT poles B 10 VAC secondary external fusing required Primary winding B Secondary winding 3 phase and neutral 10 VAC phase to phase external fusing required IEC ratings
195. ommodate the high currents associated with motor starting Fuse characteristics Pre arcing curves Pre arcing curves are sometimes referred to as time current curves They indicate minimum break currents and the ability for a fuse to pass through medium level overload current such as motor starting current The dashed part of each fuse curve indicates an area of uncertain fuse interruption Sample fuse pre arcing curves 7 60 16 202531 540 Pre arcing time seconds or minutes Jon 2 3 4 5678 10 2 3 45 6 78 10 2 3 4 5678 10 63 80 100 125 160 200 13700 A Prospective current A Source example curves based on ABB CEF fuse links Page 104 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR A fuse with a nominal rating of 50 A has a minimum break current of 200 A and is capable of passing an overload current of 240 A for 10 seconds Example Let through curves Sometimes referred to as cut off curves they indicate the ability of a fuse to limit the peak let through and rms values of short circuit current immediately downstream of the fuse installation Sample fuse let through curves 100 Ky v gt 10 bel a 2 a y Si oS t ws 5 LT c 3 1
196. on 2001 Copper for Busbars tage swi tage swi tage swi kV an tage swi or starters C http www copperinfo co uk busbars pub22 copper for busbars homepage shtml http www copperinfo co uk busbars pub22 copper for busbars homepage shtml EC 2003 IEC 60044 1 Instrument transformers Part Current transformers EC 2003 P IEC 60044 2 Instrument transformers Part 2 Inductive voltage transformers EC 2004 IEC 60228 Conductors of insulated cables EC 2009 IEC 60255 1 Measuring relays and protection equipment Part Common requirements EC 1988 P IEC 60255 6 Electrical relays Part 6 Measuring relays and protection equipment IEC 60871 1 Shunt capacitors for AC power systems having a rated voltage above 1000 V Part I IEC 61869 1 Instrument transformers Part General requirements IEC 61869 3 Instrument transformers Part 3 Additional requirements for inductive voltage IEC 62271 1 High voltage switchgear and controlgear Part Common specifications tchgear and controlgear Part 00 Alternating current circuit breakers tchgear and controlgear Part 102 Alternating current disconnectors tchgear and controlgear Part 106 Alternating current contactors tchgear and controlgear Part 200 AC metal enclosed switchgear and d up to and including 52 kV EC 2006 IEC 62271 202 High vo prefabricated substation tage swi tchgear and controlgea
197. on to medium voltage Functions to be tested include at minimum e motor starting e motor stopping e protection activation NOTE AN For installations with motor FLC gt 160 A the line and bypass contactors must be replaced by a withdrawable and fixed circuit breaker respectively LOGIC CONTROL CONFIGURATION Logic Control Configuration 3 1 Control Interface The controller must have a minimum environmental rating of IP55 The user interface shall comprise at minimum e anLCD screen for information feedback in plain English e be able to be multilingual e status LEDs indicating e motor state e starter control state e trip status e output relay activity e local pushbuttons to control e motor start e motor stop e starter reset e menu access e parameter configuration Remote control of the starter shall be possible using either two or three wire control Have multi level password protection system to prevent unauthorized parameter access but still allowing access for operators to metering functions and logs All terminals shall be of the pluggable type The control interface shall provide a means for an operator to quickly access and configure parameters The control interface shall provide an operator with a short list of critical parameters for common applications including e pump e fan e compressor e generic The equipment shall permit the operator to save the current configuration
198. open transition starters but most commonly the Korndorfer closed transition configuration is employed to eliminate the reclose transients Auto transformer connection D B9 yu o e 7xFLC MUT CUR RENE m E 4 SC DN Full voltage start current SCH Fi M 2 x FLT a X 2 Auto transformer start current x X o Full voltage torque M Y o Mg II H dee 4 Auto transformer torque 1 1 5 Load torque 6 xFLC 5xFLC 4xFLC 3xFLC Current Torque 2xFLC 1xFLC 13194 A T T T T T T T T 10 20 30 40 50 60 70 80 90 100 Speed Start performance characteristics of an incorrectly selected auto transformer starter Full voltage start current 2x FLT Auto transformer start current 1xFLT Current Torque Stall point Current and torque transient 10 20 30 40 50 60 70 80 90 100 Speed 710 12280 00A Medium Voltage Application Guide Page 13 MOORS How does soft start compare to auto transformer starting Compared with auto transformer starters soft starters are much more flexible and provide a much smoother start Auto transformer starters offer limited performance because e They offer only limited ability to adjust start torque to accommodate motor and load characteristics e There are still current and torque transients associated with steps between voltages e They are large and expensive e They
199. or a specific soft starter application In most cases the required inductance per phase will be at least 100 uH The required inductance increases as the mains supply voltage increases The following rating information is usually provided with line inductors Voltage must be at least equal to system voltage Frequency must equal system frequency Current must at least equal motor FLC Inductance as calculated Sizing guidelines for AuCom MV soft starter applications For AuCom MV soft starter installations with output motor cable runs exceeding 100 metres compensation inductance may be required Consult AuCom for advice on these applications As a general guideline compensation inductance required per phase can be calculated as Where TTE V3 x2 x Us Lcowe compensation inductance per phase uH OW 2 x didt U line supply voltage V didt SCR maximum didt rating A us NOTE AN This calculation involves many assumptions Double the required compensation inductance before selecting the output inductors Exercise Calculate the compensation inductance required for a 4 2 kV MVS soft starter installation Assume the maximum SCR didt rating to be 100 A us V3 x42 x U ko 7 y didt V3 x2 x 4200 2x100 251 pH This calculation should be doubled to use a minimum compensation inductance of 102 uH per phase 710 12280 00A Medium Voltage Application Guide Page 131 SWITCHGEAR Medium Vol
200. or vacuum circuit breakers e The main switching device is a rack in out component housed in the main switching compartment e The bypass switching device is a fixed component housed in the cable compartment In all MVX panel options the following LV equipment is standard and is mounted on the controller compartment door e Controller e emergency stop pushbutton e soft starter reset pushbutton MVX panel with contactors Pea voltage lt I kV Bowe on KI Main contactor withdrawable o Operating voltage lt kV B Oeren nox OI Main circuit breaker withdrawable 710 12280 00A Medium Voltage Application Guide Page 47 SOFT STARTERS MVX panel physical layout Front view Side view Rear view a ri STE 3 4 a c os F oi LIT D Jr pcs eS a XV Fd TER TER 3TEHIERHIEHSNI 11081 C 6 Bypass contactor circuit breaker K2 O2 Surge arrester U1 E Phase cassette power connections EN Earth switch O3 1 Controller compartment Upper LV compartment 3 Main contactor circuit breaker compartment
201. orizontal busbar system with a bus tap off that drops vertically to the bottom of the enclosure The vertical bus is connected to voltage transformers which can be of the fixed or withdrawable type Sometimes a main earth switch is supplied Metering equipment is often contained within the segregated low voltage compartment located at the top front of the enclosure geb AuCom provides a Metering Panel as part of its L Series switchgear range This is rated at 12 kV from AKS 630 A to 2000 A An IAC classification of 31 5 kA for second is achieved by double skin compartments special locking door designs and top exit arc flaps for pressure release Metering Panel MTP Typical Metering Panel p Ng Lm il BE ud 11173 A Front view Side view Rear view Oe 2 Voltage transformer fused and withdrawable Page 78 Medium Voltage Application Guide 710 12280 00A Busbar Systems Overview SWITCHGEAR Medium voltage busbar systems consist of two general arrangements The main switchgear distribution bus has three busbar sets one set per phase which run horizontally through all the panels in a line up These distribution busbars run through a dedicated chamber within each metal enclosed panel Segregation of busbar chambers between adjacent panels is provided by using insulated through bushings Inside the horizontal busbar chamber of each panel a vertical feeder bus
202. otor stopping can also be controlled by ramping down the output voltage over a predetermined time period This is particularly useful for eliminating water hammer in pumping applications Soft starters use SCRs silicon controlled rectifiers also called thyristors arranged back to back for each controlled phase of the soft starter This provides phase angle control of the voltage waveform in both directions Controlling the voltage controls the current supplied to the motor The stepless control of motor terminal voltage eliminates the current and torque transients associated with electromechanical forms of reduced voltage starting such as star delta or autotransformer starters SCR configuration per phase L1 T1 13477 A Voltage waveform QI Firing angle Conduction angle 13478 A A soft starter designed to control motor voltage is referred to as an open loop controller A soft starter designed to control motor current is referred to as a closed loop controller 710 12280 00A Medium Voltage Application Guide Page 19 SOFT STARTERS Open loop soft start control Open loop soft start controllers have no feedback of the starting performance to the controller and follow preset voltage transitions controlled by timers Open loop controller 13473 A Open loop soft start controllers can use a voltage step or timed voltage ramp approach Voltage step controllers al
203. overcurrent is applied to cables busbar systems etc Overcurrent protection can be directional which is sometimes used for more advanced selective isolation of faults Overcurrent protection HM Time overcurrent I B Instantaneous overcurrent Time s Current A 710 12280 00A Medium Voltage Application Guide Page 121 SWITCHGEAR Overcurrent protection based on measuring the 3 phase line currents produces positive sequence current I indicative of phase to phase faults or negative phase sequence current I indicative of phase loss or phase imbalance Overcurrent protection based on measuring the residual or ground current produces zero sequence current Io indicative of ground fault or earth leakage The configuration of the CTs depends on the functionality of the protection device Line current protection Line current and residual current protection L1 L2 L3 L1 L2 L3 13758 A 13759 A Positive sequence current l Positive sequence current l Negative sequence current Negative sequence current Zero sequence current lo Ground current protection Ground current protection L1 L2 L3 Zero sequence current lo Zero sequence current lo Page 122 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR In medium voltage installations differential protection is mainly used on transformers motors and generators Line currents are measured on both si
204. pe la im Lh 76 Bus Riser Panel BRPJsssssaeatncncoati gotta posit RETRAITE NITE 77 Metenne Panel TIT e sss oot ltem ilte beide ue e eines Sa uM dus 78 TEE 79 4 3 RUE 83 SwiteheearIriterloeklnig SVSEBTTIS cocti be ibt DID b tede Dd e Hue denn 83 Herman leeft ation tiet eee va etre itane tamtn tdt 85 44 Switchgear Apparate 88 Medium Voltage Circuit Breakers 88 Medium Voltage Contactors 2496 Il e Voltage e o esos tae debe oe Ec E Ren e e ER eet tu ol datura o 00 Ideas Voltage FRC Uses Ec bou M LUDUM M ME 04 C rrert LranstOrfiers soot metit te ota e d cte ctc inis bends nein dt mares 10 E e 19 Protection Deeg seenen senger 2 Moltage Transformers ace aee trend ipai cerno detalle end uid odd i ae eee din 27 Motor Eine Inductors on Soft Starter Application S ici noc ciet TEAM ERR RO 30 Medini Voltage Surge ANETO S titan oen ORO RR eva t nn N d 32 e lee TE 36 4 5 WEE EC 43 Transformer Galcvilations acssagencusingianuniadiadaniadsatimanimctimarimatimerametmaimetmarimetmalinins 43 Pente Gal Ul eth iS x t ot I og ED mU I IN co al 47 Busbar e aled ONS te o eo RR Rb a Ratte A A 49 Short Circuit Calculati risiu t n e Ua eU aad 56 Impedance leegen 59 4 6 SwiteheearInspecHon GhesldistSmisn eee menti e UU EUER RUD RUM HUE UR Ho dni UN 62 Mechanical tee Ee ee 62 Bleech Geet ere 63 Commissioning Tools and Equipment Typical e 64 4 7 Switchgear Related IEG Standards cotone t RHONE NoD de 65 4 8 Comparson er EG RE Die ET 67 Ex
205. perational or trip status e monitor the starter s current level and motor temperature using the motor thermal model Some protocols also allow you to read and write soft starter parameters For installations with no existing network AuCom also offers WinMaster a PC based software program which allows control monitoring and parameter management via an RS485 or USB connection Modbus Interface MVS and MVX soft starters can operate as slaves on a Modbus network via a Modbus Interface s B1 o GND B2 oe B3 o B Modbus interface RS485 connection onto a Modbus RTU network 13013 A e The Modbus Interface is powered by the soft starter e Each soft starter requires a separate Modbus Interface e A Modbus RTU network can support up to 31 Modbus Interfaces as slaves e The interface is configured using 8 way DIP switches For more information on using the Modbus Interface refer to the Modbus Interface instructions Profibus Interface MVS and MVX soft starters can connect to a Profibus network using the Profibus Interface pcc B Profibus interface Standard DB9 connection a D Profibus DP 3 wire network cable lt ri 5 e e The Profibus Interface requires an external 24 VDC supply e Each soft starter requires a separate Profibus Interface e A Profibus DP network can support up to 31 Profibus Interfaces as slaves e he Profibus node address
206. position e disconnectors providing isolation for maintenance and servicing must have a locking facility Methods The illustration shows a common switchgear arrangement for a medium voltage power distribution system This switchgear arrangement uses three separate interlocking methods Typical MV power distribution switchgear arrangement with interlocks TXR L TXR R X x TE ock scheme typical ck scheme 2 typical y y ck scheme 3 typical Si Fri ker left incomer m m Um left incomer transformer left b oL ae oar Ni ircuit breaker right inco R itch right incomer En l em transformer right bus zo bi ircuit breaker bus coup B En ircuit breaker left feede q itch left feeder m ircuit ker right feed on V Se H opp V m 3 itch right feeder E FL E FR E V V 13679 A 710 12280 00A Medium Voltage Application Guide Page 83 SWITCHGEAR Interlock scheme l Two incomers and bus coupler interlocking The two incomers and the bus coupler circuit breakers use a standard 2 out of 3 interlocking system to prevent a parallel feed from the two incomers onto a common bus Interlocking allows the following conditions The two incomer circuit breakers closed Q L and Q IR with the bus coupler circuit breaker open O BC 2 Leftincomer and bus coupler circuit breakers closed Q IL and Q BC with right
207. pply Once the primary power source is re established the power source is switched back to the primary power source In medium voltage systems switching is performed using either contactors or circuit breakers Most ATS controllers can control both types of switching devices Automatic changeover systems range from simple main standby set ups to highly complex distribution systems and this is where the selection of an appropriate ATS controller is important Systems can be operated in automatic or manual mode e In AUTO mode supervision and power source switching is carried out entirely by the ATS controller e n MANUAL mode power source switching is carried out by manual selection via the ATS controller NOTE For safety reasons manual mode cannot be used in certain network configurations Overview The following are examples of common operating modes in automatic changeover systems Most ATS controllers can be programmed to operate in any one of these modes NI N2 N1 N2 K1 K2 14044 A DB AUTO mode with line priority NI is the prioritised power source and if healthy will always supply the receiving network DB If NI is lost the controller switches over to power source N2 The controller switches back to INI once it has been re established AUTO mode without line priority The first power source verified as healthy will supply the receiving network DB If this power source is lost the other power source
208. pposite sides of a machine or transformer are not equal to each other L line T transformer G generator ae AuCom soft starter ANSI protection functions The following ANSI code protections are standard in AuCom medium voltage soft starters For details of additional protections in MVS and MVX which are not listed in this table refer to the relevant user manual ANSI ANSI Function MVS MVX Trip Code 26 4 4 5 s Ir Frequency relay Supply frequency 7 2 z 8 0 AC instantaneous or di dt relay Instantaneous overcurrent 64 Temperature related protection functions such as motor winding and bearing protection require a separate protection device which can be installed in the LV section of the soft starter panel Page 126 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR A voltage transformer VT or instrument transformer is used to produce a lower secondary voltage which is directly proportional to the primary voltage both in value and phase angle Voltage Transformers In medium voltage switchgear a 3 phase voltage transformer arrangement is typically derived by using three single phase transformer poles Each pole consists of a single primary and secondary winding encapsulated in epoxy resin and encased with insulating material In most single phase pole designs the primary winding has integrated fusing In a 3 phase arrangement the primary windings
209. ption POO SOR Starter Sof Starter Pana Operating current I Expec Expec Expec Altitude Alt ted start current lerr ted start time Don ted stop time tstp Switchgear requirements Incomi across the soft starter s power terminals LI L2 L3 The opera ng and motor supply configuration Operating Voltage U kV Operating voltage is the voltage kV ofthe network where the equipment is installed and is the line voltage applied ting voltage will dictate the rated voltage U kV for the equipment to be used AuCom solutions are designed to conform to the insulation requirements of IEC 62271 1 where th m th m e power frequency withstand voltage Uy kV rms minute simulates high level voltage surges on the ain supply line at standard frequency e rated impulse withstand voltage U kV peak simulates a high level voltage transient induced on the ain supply from a lightning strike This is a 1 2 50 us transient wave Operating Rated Voltage Power Impulse Rated Voltage Power Impulse Voltage U kV U kV Frequency withstand U Frequency withstand U withstand U kV peak withstand U kV peak Operating Current A Lon Los tstp SPH Ta Alt The maximum operating current I of a soft starter installation is the full load current FLC of the motor he soft starter s rated current I A must be equal to or greater than the motor FLC after consi
210. r Output Relay 61 62 64 eege eren ecce aet icut cipue Changeover Analog Output BIO B TY tege 0 20 mA or 4 20 mA Environmental Degree of Protection POWEr ASSEMBLY IPOO Controller sesse IP54 NEMA 12 Operating Temperature ww 10 C to 60 C above 40 C with derating Storage E LAN 25 C to 80 C Humidity 5 to 95 Relative Humidity Pollution EE Pollution Degree 3 710 12280 00A Medium Voltage Application Guide Page 3l SOFT STARTERS leie ME Designed to IEC 60068 EMC Emission Equipment E lee DEET Class A Conducted Radio Frequency Emission 10 kHz to 150 kHz lt 120 6 dB pV 0 15 MHz to 0 5 MHz lt 79 dB uV 0 5 MHz to 30 MHz lt 73 dB uV Radiated Radio Frequency Emission sssrin 0 15 MHz to 30 MHz lt 80 50 dB uV m 30 MHz to 100 MHz lt 60 54 dB uV m 100 MHz to 2000 MHz lt 54 dB uV m This product has been designed as Class A equipment Use of this product in domestic environments may cause radio interference in which case the user may be required to employ additional mitigation methods EMC Immunity Electrostatic Discharge 5 eot ee o tim Rd 6 kV contact discharge 8 kV air discharge Radio Frequency Electromagnetic Field sn 80 MHz to 1000 MHz 10 V m Fast Transients 5 50 ns main and control circuits 2 kV line to earth kV line to line Surges 1 2 50 us main and control circuits 2kV line to earth kV line to line Volta
211. r Part 202 High voltage low voltage EEE 2008 C57 13 2008 IEEE Standard Requirements for Instrument Transformers Melsom S W and Booth H C 1922 The Efficiency of Overlapping Joints JIEE 60 889 899 Schneider Electric 2000 Medium Voltage Technical Guide AMTED300014EN 710 12280 00A Medium Voltage Application Guide Page 221
212. r of bolts based on using high tensile steel or bronze CW307G formerly C104 Page 82 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR 4 3 Safety Considerations Switchgear interlocking systems Interlocking between different switchgear apparatus and enclosure access covers and doors enhances personnel safety as well as improving operational convenience If a switching device can cause serious damage in an incorrect position this must also have a locking facility Interlocking uses electrical and mechanical methods or a combination of both IEC 62271 200 states mandatory rules for switchgear interlocking For metal enclosed switchgear with removable switching apparatus e the switching device must be in the open position before it can be withdrawn e the switching device can only be operated in the positive service or test position e the switching device cannot be closed unless the auxiliary control circuits required to open the switch are connected Auxiliary control circuits cannot be disconnected with the switching device closed in the service position For metal enclosed switchgear with disconnectors e a disconnector cannot be operated under conditions other than those for which it is intended to be used e a disconnector cannot be operated unless the main switching device is open e operation of a main switching device is prevented unless its associated disconnector is in a positive service test or earth
213. r the motor installation and is switched in once the motor has reached full speed This method is often used on large motors running fully loaded for extended periods of time Page 136 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR To calculate the fixed capacitor bank power Q required to improve the power factor of an individual motor Calculations fixed capacitor bank for individual motor U 6 6 kV Q kVAr i Q g P kW P 1500 kW n 0 96 pf 0 88 initial power factor pf 0 95 target power factor Where Q capacitor bank power kVAr ur lane tan P motor shaft power kW n k S n motor efficiency at full load 0 phase angle of motor power factor at full load cos x pfj 0 phase angle of target power factor at full load cos x ph a tano tan6 n 1500 tan 28 4 tan18 2 0 96 1562 5x 0 54 0 33 1562 5x 0 21 328 kVAr Required power is 325 kVAr Calculations PFC capacitor bank To calculate the capacitor value C and nominal current value laom for a power factor correction capacitor bank e Capacitance Where Q C capacitance uF C Ven x 1000 Q capacitor bank power kVAr U supply voltage kV f supply frequency Hz e Nominal current _ Q nom J3xU 710 12280 00A Medium Voltage Application Guide Page 137 SWITCHGEAR Exercise Calculate the total capacitance and nomina
214. ratings e Fixed Vacuum Bypass contactor All contactors shall have the following ratings Class indoor withdrawable Rated Voltage 12 kV Rated lightning impulse withstand voltage 75 kV peak Rated 1 minute power frequency withstand voltage 28 kV rms Rated Frequency 50 Hz 60 Hz Rated short circuit breaking current 20 kA with fuses Rated short circuit making current 62 5 kA with fuses Duty continuous Utilisation factor AC3 0 Protection coordination Type 2 1 Minimum Service Life 100 000 operations at full operating current 2 2 Bi ED d mom ON gt e A pad lockable earthing switch e All panels must provide separate chambers for all main sections including Bus bars Line Contactor Soft starters and LV control The entire panel including inter chamber must be arc fault certified to 31 5kA for 1 seconds e All panels shall have the following ratings 1 IAC classified AFLR 2 Rated short term withstand current 31 5 kA for 3 seconds 3 BIL 75 kV e The equipment shall employ fibre optic cabling to ensure complete isolation between low voltage and high voltage circuitry ENVIRONMENTAL SPECIFICATIONS The equipment shall provide means to safely test its correct installation 1 The equipment shall provide a means to test the installation using a low voltage motor 2 The equipment shall provide a means to test operation of all control circuitry and protection mechanisms without connecti
215. requirements Switchgear selection is determined by considerations including Electrical conditions e System operating voltage U e System operating frequency f e Nominal operating current 1 e Short circuit current levels at point of installation Isc lan etc dyn e Horizontal busbar arrangement Environmental conditions e Ambient temperature e Altitude Pollution degree e Indoor or outdoor installation Personnel safety considerations e Internal Arc Classification IAC e Interlocking of access areas and switchgear apparatus e Access method eg tools keys process etc e Withdrawable switchgear apparatus Switchgear information for enquiries or ordering When enquiring about or ordering switchgear the supplier should at minimum provide the following information When enquiring advise the supplier of any unusual operating condition requirements eg altitude 1800 metres System characteristics e nominal system voltage and frequency e expected highest voltage e type of neutral earthing system Service conditions e any non standard service requirements which differ from normal routine Installation specifics e indoor or outdoor installation e number of phases e busbar arrangement details e rated voltage U e rated frequency f Page 72 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR e rated insulation level Ua U e rated nominal current of main busbars and feeders l
216. res of industrial soft starters can be grouped into functional categories SCR control A soft starter can control one two or three phases e Single phase controllers These devices reduce torque shock at start but do not reduce start current Also known as torque controllers these devices must be used in conjunction with a direct on line starter e Two phase controllers These devices eliminate torque transients and reduce motor start current The uncontrolled phase has slightly higher current than the two controlled phases during motor starting They re suitable for all but severe loads o e Three phase controllers These devices control all three phases providing the optimum in soft start control Three phase control should be used for severe starting situations Common control methods include e Open loop voltage ramp control Closed loop current control Soft stopping e Special control formats Adaptive control AuCom has developed a special control format known as Adaptive Control Adaptive Control is a new intelligent motor control technique that controls current to the motor in order to start or stop the motor within a specified time and using a selected profile For soft starting selecting an adaptive profile that matches the inherent profile of the application can help smooth out acceleration across the full start time Selecting a dramatically different profile can somewhat neutralise the inherent p
217. rimary voltage U prim is at its rated value Where l S l rated secondary current A V3 xU S transformer power kVA U rated secondary voltage kV i SW du Z Short circuit current Isc Assuming the transformer is fed from an unlimited supply the maximum short circuit current across the output terminals l is determined by the impedance of the transformer expressed as a percentage Percentage impedance 2 is calculated by shorting the output terminals of the transformer and increasing the applied primary voltage U from zero to a value where the rated current flows through the secondary Percentage impedance is the ratio of applied primary voltage to rated primary voltage Example If it takes 10 of the rated primary voltage to cause rated current to flow in the shorted secondary the percentage impedance Z 0 gp RH Primary secondary _ 1x100 L transformer s maximum output short circuit current A Z L rated secondary current A Z percentage impedance 710 12280 00A Medium Voltage Application Guide Page 143 SWITCHGEAR The calculated short circuit current of a transformer l is often used to rate the downstream distribution switchgear itisfeeding In reality the expected short circuit current at the switchgear installation will be less than the calculated short circuit current due to any impedance in the feeder circuit
218. rofile For soft stopping adaptive control can be useful in extending the stopping time of low inertia loads O Page 26 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS The soft starter monitors the motor s performance during each start to improve control for future soft starts The best profile will depend on the exact details of each application If you have particular operational requirements discuss details of your application with your local supplier Adaptive start profile 1 Early acceleration 2 Constant acceleration Late acceleration 4 Start time Motor speed 04827 C Adaptive stop profile 1 Early deceleration 2 Constant deceleration B Motor speed 04835 C Inputs Outputs e Digital and analog inputs with fixed or programmable functions e Relay or analog outputs with fixed or programmable functions e PTIOO or thermistor inputs with adjustable set points e Communication ports for remote control and status monitoring Protections Protection Mains frequency o G Hl Motor overload electronic thermal model Time overcurrent li nstantaneous overcurrent shearpin or locked rotor 50G Excess start time stall at start Excess starts per hour Power loss Auxiliary input trips Battery clock failure For additional information refer to ANSI protection codes 710 12280 00A Medium Voltage Application Guide Page
219. rol typical A Auxiliary supply js Control signal maintained 7 External trip contact eg from MPR H Auxiliary supply LB enne 3 External trip contact eg from MPR Control supply Clem Page 74 Medium Voltage Application Guide 710 12280 00A SCHEMATIC DIAGRAMS In medium voltage distribution networks it is important to maintain a high level of reliability Industry relies on the continuous operation of critical plant which requires no or little disruption to the electrical supply There are various methods for building redundancy of supply into a system The most commonly used methods are a dual transformer fed supply and or a standby generator sized to keep critical plant online 5 4 Automatic Changeover Systems Automatic changeover systems are designed to monitor and maintain continuous supply Today s technology allows the supervision and control of an entire distribution system from a single controller referred to as an automatic transfer switch ATS or automatic changeover unit ACU Although there are a wide range of products available they all have the same primary function The equipment monitors 3 phase voltages on all power sources Power supply sources are often prioritised and if any phase voltage on the primary power source falls outside a predetermined range for a specific amount of time the power source is switched over to a back up su
220. round fault e Undercurrent e Current imbalance e Motor thermistor e Excess start time e Power circuit e Auxiliary trip Extensive input and output options e Remote control inputs 3 x fixed 2 x programmable e Relay outputs 3 x fixed 3 x programmable e Analog output x programmable e Serial port Fibre optic cables are only supplied in IPOO variants of the MVX soft starter In all other MVX soft starters this is part of the main assembly Comprehensive feedback Digital display with multi language support Controller buttons for quick access to common tasks Starter status LEDs Date and time stamped event logging Operational counters starts hours run kWh Performance monitoring current voltage power factor kWh User programmable monitoring screen Multi level password protection Emergency stop Power Connection 15 A to 800 A nominal 2200 VAC to 11000 VAC Accessories optional DeviceNet Modbus Profibus or USB communication interfaces PC Software RTD relay Motor Protection Relay Predictive Maintenance Module PMM Page 34 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Key features MVX soft starters offer several special functions to ensure ease of use and to provide optimal motor control in all environments and applications Customisable Protection The MVX offers comprehensive protection to ensure safe operation of the motor and soft sta
221. rrnnrrnnerne 3 2 2 Physical Gpechflcations nnns 3 Logic Control topt gtratlentt eege eege eege 5 3 14 Control Interface onte te eaten t ae 5 3 2 Operating Configurations ssssssssssssseeeeenneenen enne 6 3 3 Motor and System Protection Features 6 3 4 Programmable Relay Outputs nnns 7 3 5 Programmable Control Inputs essent 7 3 6 Metering and Performance Monttoring 8 3 7 Remote Communications enne 8 SUPPOrtiand Services t SAAE EAEN 9 4 1 Commtssioning enne asaite ad iaa aaea is 9 4 2 Documentation iR ERE e RR GA eves EE ee 9 e GC ENN EC H Une DEE 9 44 Warranty and Repalr it hee e til tees 9 4 5 Standards and Approvals sse 9 INTRODUCTION Introduction 1 1 Scope This document specifies the minimum requirements for a solid state reduced voltage motor starter for medium voltage application This specification is intended as a guideline for suppliers wishing to supply their product to customer name gt for their lt project name outline of requirement gt The solid state reduced voltage starter shall control three phases at V A Hz and shall be rated to suit the application and motor characteristics Where possible motor and load curves will be provided and the supplier will use this data to justify selection The starter shall provide soft starting and soft stopping of the motor as required 1 2 Supplier Qualif
222. rs and switching apparatus There are numerous methods to calculate short circuit current levels such as impedance per unit and point to point The most commonly used and widely understood is the impedance method see below These calculation methods were widely used before calculation software became available These programs allow very accurate results to specific conformance standards Short circuit calculations serve two main functions e to determine the required make and break ratings of switchgear and the mechanical withstand of all equipment e to inform fuse selection and protection relay settings in order to achieve adequate circuit discriminations Page 156 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Formulae Short circuit Where the short circuit power of a network D is known I Sx sc V3 x U Where the short circuit impedance of a network Z is known U oXJBxZ z JR XA short circuit current kA rms peak fault current kA peak p 7 2 9 x l for a 50 Hz supply with a 45 ms DC time constant p726xl constant total short circuit impedance 2 short circuit power MVA system voltage kV total short circuit resistance Q it reactance Q for a 60 Hz supply with a 45 ms DC time N H P A a P A H C A E AX I total short circ c NOTE IN The switchgear mak
223. rter The protection characteristics can be customised extensively to match the exact requirements of the installation Advanced Thermal Modelling Intelligent thermal modelling allows the soft starter to predict whether the motor can successfully complete a start The MVX uses information from previous starts to calculate the motor s available thermal capacity and will only permit a start which is predicted to succeed Comprehensive Event and Trip Logging The MVX has a 99 place event log to record information on soft starter operation A separate trip log stores detailed information about the last eight trips Informative Feedback Screens A digital display screen allows the MVX to display important information clearly Comprehensive metering information details of starter status and last start performance allow easy monitoring of the starter s performance at all times Dual Parameter Set The MVX can be programmed with two separate sets of operating parameters This allows the soft starter to control the motor in two different starting and stopping configurations The secondary motor settings parameter groups 9 and 10 are ideal for dual speed motors or conventional squirrel cage motors which may start in two different conditions such as loaded and unloaded conveyors The MVX will use the secondary motor settings to control a start when instructed via a programmable input refer to parameters 6A and 6F nput A or B Func
224. s The rated voltage is always higher than the systems operating voltage and determines the insulation levels of the equipment Medium voltage metal enclosed switchgear is defined for use on operating voltages from kV to 52 kV Within this voltage range IEC 62271 1 defines standard switchgear rated voltages as e Series equipment used in European 50 Hz installations 3 6 7 2 12 17 5 24 36 52 kV e Series Il equipment used in Non European 60 Hz installations 4 76 8 25 15 15 5 25 8 27 38 48 3 kV Insulation level voltages Ua kV rms min and Up kV peak The defined levels are stated for phase to earth and phase to phase limits under standardised ambient conditions For installations above 1000 metres these insulation levels must be derated e Power frequency withstand voltage U This is the maximum rms voltage that the equipment can Ud withstand at mains frequency for minute It simulates power Ge surges originated from within a power system from such events T as switching transients resonance etc e Lightning impulse withstand voltage U This is the peak transient voltage that the equipment can withstand from power surges originating from atmospheric conditions such as lightning It is simulated using a standard voltage waveform Standard values for insulation level voltages E Re Current Operating current A This is the maximum rms current expec
225. s Insufficient maintenance All locations Ageing under electric stresses Pollution moisture ingress of dust vermin etc Overvoltages Source IEC 62271 200 Error by personnel Examples of possible preventive measures Selection of adequate di Use of appropriate ma Avoi Checking of workmansh mensions terials dance of crossed cables connections ip on site Correct torque Checking of workmanship and or dielectric test on site Regular checking of liqu Interlocks Delayed reopening Independent manual op id levels where applicable eration Making capacity for switches and earthing switches Instructions to personnel Use of corrosion inhibiting coating and or greases Use of plating Encapsu ation where manship by suitable means possible Correct torque Adequate locking means Checking of worl V ui V A S A pro Regular programmed m discha res to partments Surge protection Adequate insulati co ordination Dielectric tests on site routine tests ensure that the specified service itions are achieved Use of gasfilled oidance of these electrical influences by table design of the circuit oid short circuit by proper means for example tection cover LV fuses aintenance ructions to personnel i access by compartmentation bedded live parts Instructions to Page 86 Medium Voltage Application
226. s not suitable for 50 Hz and 60 Hz operation Rated current Ir A This is the rms level of current which can continuously flow through a device without exceeding tts maximum allowable contact temperature rise Temperature rise limits are defined in IEC 62271 1 for an ambient temperature of 40 C The rated current must be greater than the maximum expected load current at the point of installation Standard values for I 630 800 1000 1250 1600 2000 2500 3150 4000 A source IEC 62271 1 Rated short time withstand current Ik kA This is the maximum rms symmetrical fault current the device can withstand for a short time period without risk of damage This rating must be higher than the prospective rms fault current at the point of installation Where I2 ls Ik short time withstand current rating kA IDEST L prospective rms fault current kA Ss J3xU Sse system short circuit power kVA U system operating voltage kV Standard values for 6 3 8 10 12 5 16 20 25 31 5 40 50 63 kA source IEC 6227 1 1 Rated short circuit duration tk s This is the time the device can endure its rated short time withstand current lj without damage This value must be greater than the total expected clearing time of a fault at the point of installation Standard values for t 0 5 2 3 seconds source IEC 62271 1 If the value of t is not second the rated short circuit dura
227. s operating voltage limits For all types of earthed neutral systems U gt 125 x U Residual protection voltage Ures This is the voltage which appears across the MO arrester when it is shunting the maximum nominal discharge current to ground Using a safety margin the residual protection voltage must be somewhat less than the lightning impulse withstand voltage rating U of the equipment is it protecting System voltage Earthed Isolated Earthed Isolated Lightnin Residual y 8 8 8 kV neutral system earthed neutral system earthed impulse rotection y y P P kV min neutral system kV min neutral system withstand voltage kV y Ni y g kV min kV min rating or BIL kV max kV 72 342 n 34 3 o 9 E gne EE 9s o TR e Bo 9E 2e Xp EIER 3 M4 2 9 3 uU 89 710 12280 00A Medium Voltage Application Guide Page 133 SWITCHGEAR Exercise A 17 5 kV secondary distribution indoor switchgear system requires MO arrestors to be fitted on the incomer side The system supply is 15 kV 50 Hz and is isolated from earth Use calculated ratings and the manufacturers data sheet for selection The highlighted numbers 4 refer to the solution page Step Calculate the MO arrestor ratings e Continuous operating voltage For an isolated earthed neutral system continuous operating voltage U 2 system voltage U U 2 15 kV e Rated voltage H Rated voltage U 2 1 2
228. selection is normally predetermined eg NI then N2 then N3 MANUAL mode Select NI or N2 or N3 as the power source Page 176 Medium Voltage Application Guide 710 12280 00A SCHEMATIC DIAGRAMS NI N2 G N1 N2 G K1 K K3 14047 A DB AUTO mode with line priority NI is the prioritised power source and if healthy will always supply the receiving network DB If NI is lost the controller switches over to power source N2 The controller switches back to INI once it has been re established If both power sources NI and N2 are lost the controller commands the standby generator to start Once the generator is at correct voltage and frequency power source G is switched in to supply the receiving network DB The controller switches back to the first re established power source NI or N2 AUTO mode without line priority The first power source verified as healthy will supply the receiving network DB If this power source is lost the other power source will be selected and remain as the supply as long as it is healthy If both power sources NI and N2 are lost the controller commands the standby generator to start Once the generator is at correct voltage and frequency power source G is switched in to supply the receiving network DB The controller switches back to the first re established power source NI or N2 MANUAL mode Select NI or N2 or G as the power source NI N2 S d K1 K2 i DB1
229. sformer 2 H 0 2 indicates a current transformer with an accuracy of 1 276 and a maximum allowable secondary burden of 0 2 Q or 5 VA ona 5 A secondary CT This is a protection class rated current transformer Page 118 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR The basic principle of any current sensor is to produce a small level of secondary voltage within a specific accuracy range which is directly proportional to the measured primary current In medium voltage applications isolation between the primary and secondary circuits is critical Current Sensors Although current transformers are the most commonly used device for measuring current there are a number of other methods available Current sensors are usually designed and supplied by manufacturers as proprietary equipment to match a digital metering or protection relay Low power current sensors are ideal for use with modern digital relays which provide a low burden Sometimes referred to as hybrid current sensors each type has its own merits Rogowski coil A rogowski coil consists of a single primary winding which is normally a copper bar with termination points at both ends The secondary winding is made up of multiple turns on a toroidal non ferrous core The entire construction is encased in a dielectric insulation material The basic operating principle is that the voltage produced across a high impedance secondary load is directly proportion
230. signates the maximum error of the transformed voltage and phase angles at rated primary voltage IEC 61869 3 specifies standard accuracy classes for voltage transformers Accuracy classes for metering applications Class Application Metering class 0 2 High accuracy applications eg revenue metering Metering dass 05 and 1 0 Metering class 3 0 Rarely used Accuracy classes for protection applications Voltage error Phase shift in minutes 60 minutes degree between 0 5 1 5 x U for earthed systems between 0 5 1 5 x U for earthed systems between between 0 5 1 9 x U for unearthed systems 0 5 1 9 x U for unearthed systems Control supply power transformer sizin Sizing a control supply power transformer CPT requires analysis of the expected secondary load Information required e total inrush VA of the load e total sealed VA of the load e acceptable voltage drop level on the secondary of the transformer at inrush stage In most cases the inrush period is 20 to 100 milliseconds The power factor of the inrush current is assumed to be 0 4 for other values use the adjustment factor in the table below To select a CPT Determine the acceptable voltage drop on the secondary of the transformer at inrush stage In the appropriate voltage drop column select an Inrush VA value larger than the calculated total inrush VA of the secondary load ote the total inrush VA of the secondary load must include a
231. so called pedestal controllers apply a preset level of voltage at start then step to full voltage after a user defined period Voltage step starters have little advantage over closed transition electromechanical starters and are rarely used Voltage step soft start control E e 2 Full voltage Timed voltage ramp controllers ramp the voltage from a user defined start voltage to full voltage at a controlled rate Timed voltage ramp is used extensively in low cost soft starters 13475 A Timed voltage ramp control H Initial start voltage H Start time Full voltage T 1 13476 A The start voltage and ramp rate are often referred to as torque and acceleration adjustments but soft start can only influence torque and acceleration not provide precise control The acceleration rate is determined by the motor and machine inertia A high inertia load requires a slow ramp time if the current is to be minimised If the start voltage rises to quickly current may approach locked rotor current A low inertia load requires a short ramp time Excessive starting time can result in insufficient voltage for stable operation once the motor has reached full speed Page 20 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS Closed loop soft start control Closed loop soft starters have one or more feedback loops which monitor characteristics atthe motor The starter adjusts
232. st secondary winding cancels out the flux in the magnetic core hence the name zero 710 12280 00A Medium Voltage Application Guide Page 119 SWITCHGEAR flux The second winding generates a current in the secondary load which is directly proportional to the measured primary current This method is very accurate with a tolerance in the order of 0 02 A zero flux CT can only be used to measure DC primary current Current amplifier H B B B G 13752 A Page 120 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Protection Devices Protection devices are used in medium voltage distribution systems to protect line and cable feeders busbar systems transformers motors generators and power factor correction banks Abnormal conditions can be detected based on secondary current and voltage measurement or temperature monitoring using thermal devices When an abnormal condition is detected correct coordination of the protection devices will rapidly isolate the fault to a specific zone in the system Older protection devices relied on electromechanical relays to measure system parameters Modern protection devices are exclusively low consumption digital and microprocessor based with many communication options available Modern high end protection devices incorporate many parameter settings along with programmable logic control which provides not only protection functions but switch
233. system and instrumentation equipment and enclosures shall have the following minimum protection ratings e P4X for equipment cubicles panels and switchgear enclosures mounted in indoor air conditioned switch rooms or other non process conditioned rooms Material Quality Materials selected shall be new free from manufacturing defects and suitable for undiminished performance for the design life of the plant Materials shall be fire resistant non flame propagating and waterproof ELECTRICAL SUPPLY Glass fiber and plastic material shall withstand the operating temperatures and exposure to sunlight Appropriate measures shall be taken to prevent chemical deterioration of the contact surfaces MV SWITCHBOARD 1 2 The metal enclosed MV Switchboard under this contract shall comprise the panels as shown on the drawings and or schedules The switchboard shall comply with the latest issue of IEC 62271 1 and IEC 62271 200 and with the nominated IP rating against the external environment The switchboard shall be of the modular metal enclosed floor mounted extensible type equipped with circuit breakers busbars instruments relays and all accessories as is described in the specifications hereinafter and the Drawings All cubicles shall be of standard pattern and dimensions robust in construction dust and vermin proof and suitable for indoor use The design of the cubicles and associated equipmen
234. t floors through to the corporate environment A major advantage of Ethernet based protocols is their accessibility via the internet Industrial Ethernet protocols use the Open Systems Interconnection OSI model developed by the International Standards Organisation ISO The standard protocol stack consists of 7 layers covering the protocol requirements of all industrial automation systems Seven layer OSI model Application Layer Data Link Layer Physical Layer In basic terms industrial Ethernet protocols use a common industrial protocol at the application layer eg Modbus RTU Profibus DP or DeviceNet This is encapsulated within TCP IP protocol headers layers 4 and 3 for transport over a physical Ethernet network via layers 2 and 1 AuCom is developing Ethernet based communication options for use with its medium voltage soft starter products These options will be certified to the relevant IEC ODVA and Profibus international standards e Modbus TCP Modbus RTU over Ethernet e ProfiNet Profibus DP over Ethernet e Ethernet IP DeviceNet over Ethernet 710 12280 00A Medium Voltage Application Guide Page 41 SOFT STARTERS Predictive Maintenance Module PMM AuCom s PMM Predictive Maintenance Module provides an easy to use solution for maintenance planning Using leading edge condition monitoring techniques the PMM can pinpoint equipment failure 2 3 months in advance The PMM can be used with a wi
235. t shall be such as to enable extensions to be made at either end The switchboard cubicles shall have separate compartments for the switchgear busbars cable termination relays and controls The compartment shall restrict access to that area described above only Pressure relief flaps shall be provided on the top of each HV cubicle to relief excess pressure deeming an internal fault All circuit breakers or contactors shall be of the withdrawable isolating type with the trucks identical and interchangeable in every switchgear cubicle A positive guide shall be provided for the truck entry into the cubicle and clear indications given when the truck is at the engaged position 3 5 Busbar System 1 Busbars and electrical connections between pieces of apparatus shall be of electrolytic copper and shall be sufficiently insulated from earth and from each other to withstand the specified high voltage tests Busbars shall be air insulated All busbars shall be suitable for normal operations at rated voltage conditions and working environment without secondary insulation The busbars connections and their insulated supports shall be of approved construction mechanically strong and shall withstand all the stresses which may be imposed upon them due to fixing vibration fluctuations in temperature short circuits or other causes The busbars shall be so arranged that they may be extended in length without difficulty Connections shall be kept as
236. table functionality enabling indication of e Ready state e Low current state e High current state e Motor temperature state e Trip states with adjustable delays e Motor overload e Current imbalance e Undercurrent e Instantaneous overcurrent e Mains frequency e Ground fault e Time overcurrent e SCR overtemperature e Phase loss e Motor thermistor e Undervoltage 3 5 Programmable Control Inputs The equipment shall provide at least two programmable inputs with the following functionality e Parameter set selection e Auxiliary Trip N O e Auxiliary Trip N C e Local Remote Select e Emergency Mode Operation e Emergency Stop N C Each input must be able to be set for N O or N C operation and must have selectable delays LOGIC CONTROL CONFIGURATION 3 6 3 7 Metering and Performance Monitoring The equipment shall include comprehensive metering and monitoring functions The equipment shall provide real time feedback of operating conditions including e average current e L1 L2 amp L3 currents e average voltage e L1 L2 amp L3 voltages e mains frequency e motor real power consumption kVA e motor active power consumption kW e motor power factor e elapsed running time e time to run before programmed stop when running The equipment shall provide feedback of historical operating information including e lifetime hours run e lifetime start count e resettable hours run e res
237. tables are not available select a general purpose E rated fuse with a nominal current rating of 1 5 to 2 times the primary current rating of the transformer n FUSE 1 5 x and 2 0 x Lon Where S POTE NE MEN PRIM 43xU cu Page 106 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Select the primary input fuses required to protect an kV 400 VAC 1000 kVA 3 phase power transformer peas 1000 kVA 43x11 kV 53A Exercise 1 5x 537 97 5 A 2x53 106A The range of Lien s 97 5 106 A Use 100 A 12 kV E rated primary fuses Capacitor banks Two primary factors affect fuse ratings when used with capacitor banks e the peak inrush current which flows when a capacitor bank is energised This can be up to 100 times the nominal current rating of the capacitor bank e transient voltages produced during capacitor bank switching Individual 3 phase capacitor bank Lem 2X leap Un use 2X U_cap Back to back 3 phase capacitor bank Lem 3X leap Usus 2x U_cap Exercise Select the protection fuse required for a 300 kVAr 7 2 kV individual 3 phase capacitor bank 300 43x72 24A cap FUSE 2x _cap 2x24 48A Unus 72x U cap 22x72 14 4 kV Use 50 A 17 5 kV general purpose fuses 710 12280 00A Medium Voltage Application Guide Page 107 SWITCHGEAR Motor circuits Special motor rated fuses are used for motor starting These fuses can sust
238. tage Surge Arrestors Any system is designed with a maximum withstand voltage rating and exceeding this rating will lead to catastrophic failure Overvoltage protection devices are used in medium voltage systems to protect electrical machinery cables lines etc against damage from overvoltage transients Overvoltage transients are caused by two main events e A lightning strike causes a very fast high energy voltage transient This can produce a 8 20 us current transient in the order of 1 5 to 20 kA depending on the installation e Equipment switching causes a medium level voltage transient This can produce a 30 60 Us current transient in the order of 125 to 1000 A depending on the installation A protection device earths the current associated with an overvoltage transient This limits the terminal voltage at the point of installation to a level below the withstand voltage of the equipment 5 E HM Possible voltage without arrestors 4 Withstand voltage of equipment o0 RS We B s 8B Voltage limited by arrestors D Lightn ng overvoltages microseconds 6 2 B Switching overvoltages milliseconds 5 ee E Temporary overvoltages seconds a i s V 1 D Highest system voltage continuous E S So E gt I e Duration of overvoltage In the past overvoltage protection was provided using spark gap arrestors Today most indoor medium voltage systems use metal o
239. tation windings RH Excitation brushes x2 As motor shaft load is increased the operating power factor of the motor is reduced This power factor can be improved by increasing the DC excitation level of the rotor This behaviour allows the AC synchronous motor to operate very efficiently at a fixed speed independent of loading Soft starters are suitable for this type of application but an external DC excitation package is required for synchronous speed control and operation 710 12280 00A Medium Voltage Application Guide Page 9 MOORS 2 2 Motor starting methods When an induction motor is connected to a full voltage supply it draws several times its rated current As the load accelerates the available torque usually drops a little and then rises to a peak while the current remains very high until the motor approaches full speed Direct on line starting The simplest form of starter is the direct on line DOL starter consisting of an isolation contactor and motor overload protection device DOL starters are extensively used in some industries but in many cases full voltage starting is not permitted by the power authority ull voltage starting causes a current transition from zero to locked rotor current LRC at the instant of contactor osure LRC is typically between five and ten times motor FLC The fast rising current transient induces a voltage ransient in the supply and causes a voltage
240. tches and breaker ce Piu pro tects isolates if gt withdrawn Fixed contactor Switches Withdrawable Switches isolates if contactor Lo withdrawn SS Fuse Protects but does not e em isolate once Page 172 Medium Voltage Application Guide 710 12280 00A SCHEMATIC DIAGRAMS 5 2 Circuit Breaker Control Typical This information focuses on the double command operated DCO method of circuit breaker control DCO control uses normally open momentary contacts ie pushbuttons or a bistable relay to operate the shunt closing and opening coils Some circuit breakers use voltage fed open and close command signals while others use volt free signals Medium voltage circuit breakers can be vacuum or gas SF6 insulated with magnetic or motor charged spring operation Here are some examples of various double command operated DCO control methods Motor operated circuit breaker using voltage fed open and close command signals via momentary contact pushbuttons gp o Deme LEEFER o o Bopa Bloe Auxiliary supply Circuit breaker control open close Circuit breaker controller D External trip contact eg from MPR Control supply Command inputs common close open 14041 A 710 12280 00A Medium Voltage Application Guide Page 173 SCHEMATIC DIAGRAMS 5 3 Contactor Control Typical Medium voltage contac
241. te the typical start current Required information e Motor size kW HP e Machine type and class eg Compressor Screw Pump Centrifugal e Machine starting condition eg Conveyor Unloaded Start Page 54 Medium Voltage Application Guide 710 12280 00A SOFT STARTERS If information is available about the intended motor s locked rotor current LRC and locked rotor torque LRT the motor s start performance can also be factored into the assessment Even better estimates are obtained where information on the machine start torque requirement are also known Assessed Start Current Estimate Required information e Motor size kW HP e Motor locked rotor current LRC e Motor locked rotor torque LRT e Machine starting torque FLT Calculation Calculations use percentages of full load torque and full load current Minimum required start current Where lag minimum required start current 76 motor FLC Isr LRC xm LRC Motor locked rotor current 76 motor FLC Tan Minimum required start torque to accelerate machine from standstill 76 motor FLT LRT Motor locked rotor torque 76 motor FLT Example A 1100 kW 3 3 kV motor has a full load current of 235 A and a locked rotor current of 500 FLC The motor is required to start a pump with a minimum start current of 1576 motor FLT The motor s locked rotor torque is 150 FLT las 500 FLC UEL 500 x 0 316 158 FLC 158
242. ted to flow through the equipment The operating current must always be less than or equal to the rated current of the equipment Rated current l A This is the maximum rms current the equipment can continuously operate at under normal conditions This rating is based on an ambient operating temperature of 40 C within an allowable maximum temperature rise For temperatures above 40 C switchgear rated current must be derated IEC 62271 1 specifies standard ratings as base 10 multiples of 1 25 1 6 2 2 5 3 15 4 5 6 3 8 Page 168 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Maximum permissible temperature rise temperature C 40 C ambient C 10 35 ios s Tincoated ooo H 50 Bolted connection or equivalent in air Bare copper bare copper alloy or bare aluminium alloy 99 ilver or nickel coated Tin coated Source derived from IEC 6227 1 Peak withstand current Ip kA This is the peak current the equipment can withstand in the closed position from the first loop of a short circuit fault This current contains a symmetrical AC component superimposed on a decaying DC component Peak withstand current is defined as 2 5 times the rated short time withstand current for 50 Hz installations and 2 6 times the rated short time withstand current for 60 Hz installations The switchgear peak withstand current rating must be higher than the calculated peak dynamic
243. ter a delay motor start circuit breaker QIOA closes 9 Al takes control of motor and controls its stopping 10 The master stops Al and motor start circuit breaker QIOA is opened The main output circuit breaker Q2 is opened and the stopping sequence is complete Manual mode operating sequence NOTE In this example The main input c Each moto directly fed Eac Q ded h motor is sta Each moto is d ircuit breaker Q ris manually started in into an input of the m r is manually stopped in any order This is usually via a stop push irectly fed into an input of the master controller A2 Only a motor freewheel stop is available rted direct on lin OB Q20B Q30B Motor protection is provided in this circuit via a set icated motor protection relay the electronic motor starter A1 is not used to control any motor starting or stopping and main output circuit breaker Q2 remain open any order This is usually via a start pushbutton for each motor which is aster controller A2 e and fed from the main input bus via the motor s bypass circuit breaker of current transformers and a for each motor button for each motor which 710 12280 00A Medium Voltage Application Guide Page 63 SOFT STARTERS AuCom multi motor starting solution AuCom offers a proprietary solution that allows a single MVS or MVX soft starter to individually control up to 8 me
244. terial If the busbar is carrying AC current the operating frequency has a slight effect on the busbar rating due to magnetic skin effect A busbar system has a short time withstand current rating The temperature rise in the event of a short circuit condition must not exceed the thermal limits of busbar standoffs Typical current ratings and nominal dimensions for medium voltage busbar systems NOTE Dimensions should be used as a guideline only and may vary The dimensions stated in this table are based on bare copper at ambient temperature of 40 C maximum permissible temperature rise of 50 C operating at 50 Hz Rated current Bar dimensions Rated short time withstand Rated short time withstand per phase current period A W x D mm l kA tk seconds 1250 80 x 10 160 100xl0 25 16 20 25 31 5 40 50 0 5 1 2 3 Source current rating information is derived from IEC 62271 Most medium voltage switchgear including busbar systems have short time withstand ratings of 16 kA 20 kA 25 kA or 31 5 kA for 3 seconds Page 80 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Temperature rise During short circuit conditions the busbar will rise in temperature depending on the level of short circuit current and time duration This temperature rise must not exceed the thermal limits of any equipment in contact with the busbar Maximum permissible temperature rise for bolt connected devi
245. ters for alternating systems up to 38 tage switchgear and controlgear AC metal enclosed switchgear and ove kV and up to and including 52 kV trolgear AC insulation enclosed switchgear and ove kV and up to and including 52 kV voltage switchgear and controlgear Gas insulated metal enclosed itchgear for rated voltages above 52 kV voltage switchgear and controlgear Rigid gas insulated transmission lines rated voltage above 52 kV tage switchgear and controlgear Compact switchgear assemblies for ted voltages above 52 kV igh voltage switchgear and controlgear Voltage presence indicating systems for 61958 ted voltages above kV and up to and including 52 kV i tage switchgear and controlgear Seismic qualification for gas insulated 62271 2 itchgear assemblies for rated voltages above 52 kV tage switchgear and controlgear Seismic qualification of alternating circuit breakers tage switchgear and controlgear Dimensional standarisation of HERR tage terminals 710 12280 00A Medium Voltage Application Guide Page 165 6227 302 igh voltage switchgear and controlgear Alternating current circuit breakers ith intentionally non simultaneous pole operation 62271 303 High voltage switchgear and controlgear Use and handling of sulphur 61634 hexafluoride SF 6227 304 igh voltage switchgear and controlgear Design classes for indoor enclosed 60932
246. test techniques General defni ionsandtestrequremens e0072 Insulation coordination Appicaiongdde e Degrees of protection provided by enclosures IP Code 60909 0 Short circuit currents in three phase AC systems Calculation of currents h 61869 3 nstrument transformers Additional requirements for inductive voltage 60044 2 60186 transformers ion rees of protec provided by enclosures for electrical equipment against rnal mechanical impacts IK Code tage swi r Common specifications 60694 tage swi ti ircuit breakers 61633 62271 308 62271 101 igh voltage switchgear and controlgear Synthetic testing Sege g 02 ig tage switchgear and trolgear A t nt disconnectors and 60129 61128 ri 8g switches 61129 61259 i tage switchgear and controlgear Switches for rat tages above kV 60265 to and including 52 kV tage switch t ti t switches for rated of52kVa tage swit t ti t switch fuse binations tage switchgear a trolgear Alternati t contactors controllers motor starte voltage swit it switchers voltage swit trolgear High volt ternating current onnecting circul rated voltages of and above voltage swi t ternati t series capacitor ass switches gear Inductive load voltage switchgear al trolgear Overhead pad mounted dry vault submersible automatic circuit reclosers and fault interrup
247. th the equipment The equipment supplier shall undertake to deliver the complete training programme if required by the customer The training programme shall be delivered at the customer s premises or at the supplier s premises as required by the customer The training programme shall deliver to the customer the skills to e appropriately programme the equipment to meet customer requirements e safely commission the equipment e safely operate the equipment e identify and rectify operating problems caused by incorrect programming e identify and diagnose operating problems caused by faulty equipment Warranty and Repair The supplier shall guarantee the equipment against faults of materials or manufacture workmanship for a period of not less than 18 months from the date of manufacture The supplier shall guarantee to provide servicing support for the equipment for a period of not less than 10 years Standards and Approvals The equipment must as a minimum comply with and be certified to e JEC 62271 200 e IEC 60947 4 2 e IEC 60664 e IEC 60529 e NZS4219 e IEEE 242 e CE EMC EU Directive e C tick EMC Requirements e Marine Lloyds SPECIFICATION Power factor Correction MEDIUM VOLTAGE CONTENTS Contents ee Et OIA E 2 ES Kee 2 1 2 Supplier Oualtftcattons sese 2 Environmental Speclficallons 5 on oen ences ate 3 2 1 Environmental Specifications sees
248. the required short circuit breaking capacity of a circuit breaker with a pole opening time of 45 ms and an expected symmetrical short circuit fault level of 21 kA at the point of installation rt lI0 45 55ms tal opening time of 55 ms is 30 90 80 70 60 50 40 T4 45 ms 30 20 10 0 13721 A D 5 10 15 20 2 30 35 40 45 50 55 60 65 70 75 80 85 90 Time interval from initiation of short circuit current ms 710 12280 00A Medium Voltage Application Guide Page 93 SWITCHGEAR Transient recovery voltage TRV TRV is the voltage transient that appears across a circuit voltage TRV waveforms vary depending on the charac IEC 62271 100 specifies test conditions under which the The test results are published as specific circuit breaker n breaker pole when current flow is interrupted at its rated teristics of the supply and the load circuit breaker must endure standard TRV waveforms ameplate ratings A circuit breaker must be able to break the current for any TRV condition likely to occur at the point of installation An IEC classification can be given to a circuit breaker depending on its likelihood to restrike ie re establish the current flow after the initial current has been disrupted If restrike starts to occur on a regular basis this usually indicates that the circuit breaker needs maintaining
249. ther equipment and in severe situations cause equipment failure e Reduce the size of electrical transformers switchgear and cable e Reduce maximum demand charges from the electricity supplier Mechanical Benefits e Minimise start torque levels to match application requirements This eliminates mechanically damaging torque transients associated with electromechanical starting methods e Smooth stepless torque is applied to the load from the motor shaft This can e reduce pipeline pressure surges and water hammer in pump applications e eliminate belt slippage associated with belt driven loads e eliminate belt slap associated with large belt conveyor applications e Reduce maintenance and production down time Application Benefits e Optimise performance for any motor and load combination e Soft stop reduces or eliminates water hammer in pump applications e Simplicity The soft starter provides a complete motor control solution in one package This includes advanced motor protection input output signals for remote control monitoring and a wide range of communication options Page 22 Medium Voltage Application Guide 710 12280 00A 3 3 Anatomy SOFT STARTERS Key components Most soft starters have the following main components SCRs also called thyristors Snubber circuits Heatsink Fans optional for increased thermal ratings Busbars Current sensors Printed Circuit Boards PCBs Housing Example MVS I
250. tion Fibre Optics The MVX uses two line fibre optic connections per phase between the low voltage control module and the high voltage phase cassette for electrical isolation This fibre optic link simplifies installation of chassis mount MVX starters into custom panels MVX Phase Cassette The MVX phase cassette is a robust and extremely compact design for easy integration into a panel enclosure The unique draw out design simplifies general maintenance and servicing A service lifting trolley is supplied with each MVX panel or phase cassette for easy installation and removal MVX phase cassette Rack in rack out phase cassettes Isolated control via fibre optic connections 710 12280 00A Medium Voltage Application Guide Page 35 SOFT STARTERS General Technical Data Supply Mains Voltage Merc OM kV Phase phase Rated Frequency Dr c AE 50 60 Hz Rated lightning impulse withstand voltage U Merc M M 75 kV Rated power frequency withstand voltage Ua Miss cAMP a E 42 kV Rated short time withstand current symmetrical RMS lj Ie Ul eet 31 5 kA for 100 ms Form Designation aseo n EROR RARI eege Bypassed semiconductor motor starter form Control Inputs Start ubenminals 23 624 E 24 VDC 8 mA approx Stop Terminals C31 C32 24 VDC 8 mA approx Reset Terminals C41 C42 Input A Terminals C53 C54 2
251. tion must be published on the circuit breaker nameplate 710 12280 00A Medium Voltage Application Guide Page 91 SWITCHGEAR Rated peak withstand current kA This is the maximum peak fault current level which the device is able to close make on This rating must be greater than the expected peak let through Rated peak withstand current 2 j P 45 ms L 26x l 45 ms 2 5 x for a 50 Hz supply with a DC time constant for a 60 Hz supply with a DC time constant fault current l at the point of installation Where lo asymmetrical peak let through fault current from the first fault loop kA L rms symmetrical fault current level with no DC component kA Source IEC 62271 1 IEC 62771 100 Rated short circuit breaking capacity Isc kA This is the highest level of rms current which the circuit breaker can successfully open break on a fault at its rated voltage When a short circuit occurs in a 3 phase system the initial fault current is asymmetrical and is made up of an AC symmetrical component and a decaying DC component The rated short circuit breaking capacity must be greater than the expected asymmetrical fault current level when the circuit breaker poles are opened Ic 2la la l5 lg Where L rated short circuit breaking capacity of circuit breaker kA L asymmetrical fault current level when circuit breaker poles are opened kA L
252. tions to be tested include at minimum e motor starting e motor stopping e protection activation LOGIC CONTROL CONFIGURATION Logic Control Configuration 3 1 Control Interface The equipment shall be suitable for being supplied as a loose item with an IPOO unit for flush mounting into the control portion of a cubicle The controller must have a minimum environmental rating of IP55 The user interface shall comprise at minimum e anLCD screen for information feedback e be able to be multilingual e status LEDs indicating e motor state e Starter control state e trip status e output relay activity e local pushbuttons to control e motor start e motor stop e Starter reset e menu access e parameter configuration Remote control of the starter shall be possible using either two or three wire control Have multi level password protection system to prevent unauthorized parameter access but still allowing access for operators to metering functions and logs All terminals shall be of the pluggable type The control interface shall provide a means for an operator to quickly access and configure parameters The control interface shall provide an operator with a short list of critical parameters for common applications including e pump e fan e compressor e generic The equipment shall permit the operator to save the current configuration to an internal file There shall be two files available
253. tors have two methods of control e single command operated control SCO this requires a permanent signal to close and maintain the contactor in the closed position Removal of the control signal will open the contactor e double command operated control DCO this requires two separate momentary contacts one for the close command and one for the open command The DCO control method typically uses normally open spring return pushbuttons for both the open and close commands Typically command signals require an external voltage source and the contactor controller itself requires a separate auxiliary voltage source Depending on the contactor make and model electrical options are available Some examples are Undervoltage shunt trip only used with DCO control Lock out solenoid needs to be externally energised before contactor main poles can be electrically operated Racking solenoid needs to be externally energised before a withdrawable contactor can be moved between the test and service positions Auxiliary contacts indicate the electrical state of the main contactor poles Racking contacts indicate whether a withdrawable contactor is in the service or test position Fuse blow indicator contacts indicate fuse condition operated by striker pin and only available on contactors with integral medium voltage fuses The following examples show typical contactor control circuits Single command operated contactor cont
254. transformer feeder circuit The primary current for TXR2 is 105 A Step 2 Calculated maximum expected short circuit current at CT2 installation Isc A Ignoring any power cable or busbar impedances lL x 100 n lsc 105 x 100 5 2100 A The maximum expected short circuit current at CT2 is 2100 A Step 3 Select protection CT2 ratings Primary rated current 1 25 xl pr I 0 1 0 1 25 x 105 Use a rating of 50A Secondary rated current Use a rating of A Short time withstand rating in ex Use a rating of 10 kA Primary circuit voltage U 2U Use a ratings of 12 kV Real output power typically gt VA for digital type protection relay Use 2 5 VA this allows 1 5 VA for cable burden etc Step 4 Calculate protection class 5PX The instantaneous trip current level of protection relay OC2 is set to 10 x I _trip 10x 105 1050 A primary current Note In most digital protection relays the trip current levels are set with respect to the secondary current In this case 1050 d 150 7A sec The instantaneous trip current level for the CT secondary is 7 A The trip current level should fall between 100 to 50 of the accuracy limit factor ALF Using an ALF of 10 5P10 the trip current level of 1050 A falls within the range of 100 to 50 ALF so a 5P10 protection class CT is suitable 100 ALF 1 0x10x150 1500 A 50 ALF 0 5 10 150 750A 750 lt
255. ts Characteristic Solid foreign objec Characteristic 2 Harmful ingress of st the ingress of different items Ingress protection IP codes are LS iquid Additional letter optional Object used for access Supplementary letter optional Ap plication specific IP rating components Characteristic Characteristic 2 Additional Letter Supplementary Letter D Non protected on protected A back of hand H high voltage apparatus 2 50 mm diameter Vertically dripping B finger M motion during water test 2 212 5 mm diameter Dripping at 5 tilt C tool S stationary during water test 3 2 2 mm diameter Spraying D wire W weather conditions 4 2 1 0mm diameter Splashing 5 Dust protected etting 6 Dust tight Powerful jet 7 Temporary immersion 8 Continuous immersion Source IEC 60529 IEC 62271 1 specifies protection ratings for enclosures Equipment designed for indoor installation is not typically IP rated agai IP ratings for equipment installed indoors nst ingress of water a placeholder X is used instead of a rating for this characteristic Degree of Protection against ingress of solid foreign Protection against access to hazardous parts Protection objects IPIXB Protected against solid objects greater than
256. ture P PTC R RTD 50 AC Activates if the current or di dt values N G instantaneous or exceed a preset level Normally indicates a di dt relay medium to high level fault condition N neutral G ground 5 AC Activates when the current exceeds a N G time overcurren preset level based on a thermal overload t relay trip curve N neutral G ground 59 Overvoltage Activates if the voltage exceeds a preset relay evel 64 Ground earth Activates when earth current flow is detector relay detected from the frame chassis case or structure of a device indicating a breakdown of insulation in an electrical machine or transformer 710 12280 00A Medium Voltage Application Guide Page 125 SWITCHGEAR Function Description Application Components required AC directional Activates when the current flowing in a current relay specific direction exceeds a preset level This protection is based on 50 and 51 Incomer feeder Power factor EM oi unctions AC reclosing Controls the automatic reclosing and relay ocking out of an AC circuit switching device Frequency relay Activates if the frequency falls outside a preset range Locking out Shuts down or holds equipment relay service under abnormal conditions May be manually or electrically operated Differential Activates if the detected current protection relay o
257. uency has reached supply frequency 4 The master stops Al motor start circuit breaker Q10A is opened and after a delay motor bypass circuit breaker QIOB is closed 5 Motor 2 start circuit breaker Q20A closes then after a delay Al starts motor 2 and takes the motor to ful running speed 6 The master stops Al motor 2 start circuit breaker Q20A is opened and after a delay motor 2 bypass circuit breaker Q20B is closed 7 Motor 3 start circuit breaker Q30A closes then after a delay Al starts motor 3 and takes the motor to ful speed 8 The master stops Al motor 3 start circuit breaker Q30A is opened and after a delay motor 3 bypass circuit breaker Q30B is closed 9 The main output circuit breaker Q2 is opened and the starting sequence is complete Stopping control sequence The master controller A2 issues a system stop command The main output circuit breaker Q2 closes 2 Motor 3 bypass circuit breaker Q30B opens and after a delay motor 3 start circuit breaker Q30A closes 3 Starter Al takes control of motor 3 and controls its stopping stop duration is programmed in Al 4 The master stops Al and motor 3 start circuit breaker Q30A is opened 5 Motor 2 bypass circuit breaker Q20B opens and after a delay motor 2 start circuit breaker Q20A closes 6 Al takes control of motor 2 and controls its stopping 7 The master stops Al and motor 2 start circuit breaker Q20A is opened H Motor bypass circuit breaker O 0B opens and af
258. uit breaker can be closed using the interlock key retrieved from the bus coupler circuit breaker This key interlock system only allows for any two circuit breakers to be closed at the same time Electrical interlocking Normally closed auxiliary contacts from the two incomers and the bus coupler circuit breakers are used to electrically interlock the close command of each circuit breaker e Lleftincomer circuit breaker O IL has a normally closed auxiliary contact from the right incomer circuit breaker Q IR and a normally closed contact from the bus coupler circuit breaker Q BC connected in parallel to allow a close command ct e Right incomer circuit breaker Q reaker Q IL and a normally closed contact from the bus coupler circuit breaker Q BC connected i arallel to allow a close command R has a normally closed auxiliary contact from the left incomer circui al b p e Buscoupler circuit breaker Q BC has a normally closed auxiliary contact from the left incomer circuit breaker Q IL and a normally closed contact from the right incomer circuit breaker Q IR connected i parallel to allow a close command This control method only allows for any two circuit breakers to be closed at the same time Interlock scheme 2 Incomer circuit breaker and earth switch interlocking The incomer circuit breaker Q IL or Q IR and earth switch E IL or E IR are me
259. uit breaker position cannot be changed unless the circuit breaker main poles are electrically open 710 12280 00A Medium Voltage Application Guide Page 89 SWITCHGEAR When a withdrawable circuit breaker is integrated into a metal enclosed switchgear compartment electromechanical interlocking is used to ensure safe operation such as e the circuit breaker switchgear compartment door cannot be opened unless the circuit breaker is electrically open and physically racked out to the test position e isolation barrier shutters are automatically operated according to the circuit breaker truck position e when an earth switch is incorporated into a metal enclosed switchgear panel with a withdrawable circuit breaker the earth switch can only be closed if the circuit breaker is electrically open and physically racked out to the test position ed The main advantage of a withdrawable circuit breaker compared with fixed type circuit breakers is the ability to safely disconnect and isolate the main circuit for maintenance or circuit breaker replacement a SES Ess LB 200 E TWAVAS VAVAS B ne CD d SSES zb D d DER E Ai e le i lt H E_E S oo 8 Control methods Compatibility between circuit breaker types and control methods Circuit breaker type control signal control signal breaker eg oem t t operate WESS stored energy op
260. urs run e lifetime start count e resettable hours run e resettable start count e resettable kWh count The control interface shall allow the user to select which parameters to display on the LCD The equipment shall record full details of its state at the time of every protection activation The recorded details shall include at minimum e time and date stamp e protection type e motor operating status e mains frequency e line current e line voltage The equipment s protection log shall store no fewer than eight trips The equipment shall record all changes to its configuration The equipment s change log shall store no fewer than 99 events Remote Communications The starter must have the ability to download parameters and monitor via a computer during commissioning Optional Remote communications be available for the following interfaces to both monitor and control the soft starter e Modbus RTU e Profibus e DeviceNet SUPPORT AND SERVICES Support and Services 4 1 4 2 4 3 4 4 4 5 Commissioning The equipment supplier shall be capable of providing commissioning of the equipment Documentation Training The equipment shall be provided with a complete set of user and support documentation including e User manual e Recommended list of spare parts e Schematic amp GA drawings The equipment supplier shall be capable of providing a complete training schedule wi
261. ust continuously sustain its rated current without exceeding its thermal limits e inthe closed position a circuit breaker must sustain a specific fault current level lj for a short time period t A circuit breaker s short time withstand fault current rating must exceed the expected rms symmetrical fault current level l at the point of installation e a circuit breaker must be capable of sustaining electrodynamic and thermal stresses associated with the peak let through energy of a fault The circuit breaker s make rating must exceed the expected peak fault current level I at the point of installation _ Where ye lt A VUE S EES asymmetrical peak let through fault current from the first fault 45 ms DC time constant P l 2 6 x for a 60 Hz supply with a loop kA ae rms symmetrical fault current level with no DC component 45 ms DC time constant 3 kA p 1 omera rms current IC instantaneous peak current Current 13716 A Time Construction Main switching contact design has two primary components e asuitable insulation medium to minimise the physical size of the apparatus e a method to reduce any arc and extinguish it during contact breaking Modern medium voltage circuit breakers tend to be either vacuum or SF6 gas insulated sulphur hexafluouride Oil filled circuit breakers are less common Page 88 Medium Voltage Application Guide 710 12
262. vidually checked Examples of differences in rating requirements Similar standards may have differences in ratings specifications design requirements and test procedures AN e ANS C37 20 3 stipulates design requirements includin NOTE This list gives some examples of differences between major standards Always refer to the specific standard s for full details The standard value of rated duration for short time wit 2 seconds for ANSI C37 20 3 The acceptable limits for temperature rise of busbars a EC 62271 1 present in IEC 62271 e ANSI and IEC stipulate different testing requirements and procedures hstand current is second for IEC 62271 1 but re more stringent in ANSI C37 20 3 than g materials fusing and interlocking that are not 710 12280 00A Medium Voltage Application Gu ide Page 167 SWITCHGEAR 4 9 IEC Switchgear Rating Definitions IEC 62271 1 defines standard ratings for medium voltage switchgear These ratings allow selection of equipment to match the electrical characteristics at the point of installation Voltage Operating voltage U kV This is the system s operating voltage at the point where the switchgear is installed The operating voltage must always be less than or equal to the rated voltage of the switchgear equipment Rated voltage U kV This is the maximum rms voltage the switchgear equipment can continuously operate at under normal condition
263. xide MO arresters which provide a compact and dependable solution for overvoltage protection MO arresters are covered by IEC 60099 4 and IEEE C62 22 2009 MO arresters are often used in gas insulated indoor switchgear to avoid restrike during equipment switching add ee Application and selection MO arrestors are usually connected from each phase line to earth at close proximity to the equipment being protected When the system voltage is within the normal operating range the arrestor s resistance is high Ata predetermined knee point the resistance reduces rapidly in response to rising voltage This provides a low resistance path for current to be diverted to earth When this happens a residual protection voltage U appears across the arrestor terminals An MO arrestor is selected so that the lightning impulse withstand voltage level U or BIL of the equipment is 1 4 times the residual protection voltage Ue developed when maximum transient current is flowing to earth LOE Leakage current mA Nominal discharge current kA Continuous operating voltage U kV DH Rated voltage U kV D Residual protection voltage U e kV Line to earth peak voltage kV 13803 A Discharge current A Page 132 Medium Voltage Application Guide 710 12280 00A SWITCHGEAR Selection Ratings There are four ratings to consider when selecting MO arrestors for an installation Nominal discharge current In

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