IDAX Application Guide – DFR Measurements on Current
Contents
1. P HE aS E Tf E g m mf mi a 4 2 fe 1 Pas e t 4 Seas ce i Ea E a f ZE ai k re ab z e A a pe fe E _ _ p i E z F al A th oP Lili any aE I Mia w 9 9 Gland plate Gl Primary terminal i Lifting lugs Metallic expansion bellows 111 Bellows indicator El Oil filling screw H High voltage insulation E Porcelain insulator IE Secondary winding 5 secondary terminal box and cores E Secondary terminals H Primary winding Oil drain valve Transformer head EJ Grounding terminal aluminum Figure 7 IOSK Oil immersed CT Design Details Trench Group presents two designs one for voltages from 72 5 to 170 kV and the other one for voltages in the range from 245 to 550 kV 1 3 6 Type OSKF outdoors Oil Paper insulation Current Transformer Trench type OSKF Current Transformers are defined as head type Current Transformers These CT s are designed and constructed with the well proven highly reliable oil paper insulation system Each porcelain housed hermetically sealed current transformer is equipped with stainless steel expansion bellows calibrated to the internal oil volume and extremes in operating and ambient temperatures Megger Sweden AB phone 468510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 9 26 CT cores Aluminum core2. Megger Application Information 1 26 2010 01 05 IDAX Application Guide DFR Measurements on Current Transformers Abstract Revision history Date Revision Comments __ _ _ 2009 11 14 PAR 2009 11 14 PAS 2010 11 15 ee 2010 01 05 PPAR Megger Sweden AB phone 46 8510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 2 26 2010 01 05 Content 1 Medium and High Voltage Current TranstOriits sccissccssecscadiseaasvadevareccncculesvaoaswa veceasdussawadlanseteuledscadeensovaaievs 3 1 1 eneral Ta Orna ec E E a 3 1 2 Risk of Unknown Conditions during Operation i 5 ccicscsusaececnaassweesensedaahoanaustavibeadsacganiesasedaaaustonnianbiasGes 3 1 3 Construction of Current TEATS TOTIMNCTS poi ocns000 a0esducdwnes caauinopasensinncaenssbaxenondtvnnavenssbsenmpadelbneanotienmbansiiens L31 Outdoor Molded Epoxy Wound Type Metering Relaying CT 15 25 34 5 46 69 kV 4 L32 Outdoor Molded Resin Window Type Metering Relaying CT 5 8 7 15 25 34 5 KV 5 1 3 3 Type COF Outdoor Oil Filled Wound Type Metering Relaying CT 15 25 34 5 46 69 E A E E ee me ares 6 1 3 4 Type CA Outdoor Oil Filled Wound Type Metering Relaying CT 230 345 500 765 kV 7 Laos Type IOSK Outdoor Oil Paper Insulation Current Transformer ccccccccceeeeeeeeeeeeeeeeeees 7 1 3 6 Type OSKF outdoors Oil Pa
3. 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 17 26 2010 01 05 Select GST measurement and connect IDAX to the CT as described Results File Edit Diagram View Configuration Help air a gt m E pes IL 4p CT_application_note 2009 11 12 Test_1 General Sweep WQuick Test Measurement Plan Graph Table 60Hz Data Test Capacitor x A Model Transformer General Measurement Plan Label labc CT_application_note 2009 11 12 Test_1 BY 2w ch U 140 Y RMS Stop freq 0 001 Hz Frequency Sweep ES 2w cl EA General Sweep Configuration HMO_CFE CT and PT test f x HMO_TC NUM SERIE U0047 3 C usT 1 Measure Input 1 Input 2 grounded Earth ground act as guard HMO_te u 0047_2 UST 2 Measure Input 2 Input 1 grounded Earth ground act as guard HMO_tpe serie MMO3000 1 H HMO_TPI 13 8 KV C USTA 2 Measure Input 1 Input 2 Earth ground act as guard X HMO_TSP COMODIN GST Measure earth ground Input 1 Input 2 HMO_U 0047 2 C GST Guard 1 Measure earth ground Input 2 Input 1 is guard C GST Guard 2 Measure earth ground Input 1 Input 2 is guard GST Guard 1 2 Measure earth ground Input 1 and Input 2 are guard V Use frequency list defined below instead of default frequencies 1000 470 220 100 70 50 20 10 4 6 2 2 1 0 46 0 22 0 1 0 046 0
4. 20 ated Material Oil bd j2 1 44E14 jy as S a he Permitivity Conductivity X you Temp Figure 15 IDAX Test on OSKF 123 6 2 CT OSKF 123 C400 C800 RF 1 5 When the test is carried out on an instrument transformer it is important to consider a minimum amount of Y 0 5 because the solid insulation is mainly paper wrap The analysis generates a 0 262 PF value reflected in 2 9 moisture content in cellulose but a very low conductivity of the oil Another important factor to be considered is the rated nominal voltage of the unit this creates a difference based on the ratio of oil paper insulation Interesting to highlight here is that similar size units are used for different current ratios MODS v2 0 0 0 File Configuration Diagram Automatch Help PF 8 aa lca fee faked root wis bo oh 4 ened paket Soret Jel pal nl rd ty fone itech Pack ei tone fel po Sena pee Nd oN dy BA a A deck stelddvtcacccbus sduc JocUsLU bacon scsulecalcc dacs edckSicacaceclsu wisadecs Modal LWancces IsowckasdenadaleGhlacdaccdas estewe Sas ead cleats hal piel gia ted als By batten Mel plata beds Cates shat ale Yat ct fa aaiae cated daia tole al obs hel ai h Settee bal cleats tober fate etal bal ol ch aaa etala plotted vated feta ma toh fated th folate ota a aaa aa Na aa lool ai Worl so Scr pal macs cb Pea cM oles ao Nal adad aan Gdns aa ca Tet oh etal olan lls ede rar al cl gh telat a
5. 6 Flange Outlet Tube ___ Composite Insulator a Terminal Bew pen Figure 10 Gas Insulated CT Error Reference source not found summarizes the above described construction designs for Current Transformers primarily used in North America Current Transformer ees Oe kV Design 5 87 15 25 34 5 230 345 500 765 meee Teper Wound Type Ri A eA e Window Type meee eee ee Wound Type CA Outdoor Oil Filled Wound Type c w bellows Oil Filled Wound Type Single Phase Metering Combined CT VT unit KAKAKATA ZAMN c w bellows O AMARORE c w bellows weee KC eee e insulation pms Te SFe Table 1 Typical CT Designs for MV HV Applications Megger Sweden AB phone 46 8 510 195 00 Eldarv gen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 12 26 2010 01 05 2 DFR measurements on Current Transformers 2 1 Measurement Setup For oil immersed CTs measurements are carried out following the general safety recommendations described in section 1 6 1 of the IDAX User s Manual Remember that the unit should be off line and the unit under test should preferably have stabilized temperature variation after operation The average temperature of the insulation must be measured estimated and recorded One option is to measure on several positions on the outside of the CT with a Pistol Grip Laser Target Temperature Gauge or
6. X Y Temp This unit has the same result as the previous examples but with completely different insulation geometry Figure 18 IDAX Test on OSKF 245 Megger Sweden AB phone Eldarvagen 4 email 187 29 Taby website Sweden 46 8 510 195 00 info paxdiagnostics com www paxdiagnostics com www megger com Megger Application Information 23 26 2010 01 05 6 5 CT OSKF 145ER 0 15B1 8 RF 2 0 MODS v2 0 0 0 File Configuration Diagram Automatch Help Model sited n A 2 PF 5 Rx Powerfactorat60Hz ode 0 289 Ai Conductivity fi 30E 13 Vv Figure 19 IDAX Test on OSKF 145ER This unit has a high PF value of 0 309 as well as higher oil conductivity 1 3E 13 than above units These values would be investigated further using Partial Discharges and HV Impulse Test in a factory but in a substation this unit shows normal ageing and does not require maintenance as moisture is at an acceptable level 6 6 COF 350 CT 0 3B1 8 RF 1 5 2 0 This example is interesting as it illustrates the capabilities of the IDAX This unique example does not reflect a typical maintenance situation but shows the capability and accuracy of the method by comparing results before after the repair when the paper has been subjected to ambient air and finally after final oil and vacuum process The reason for the repair was that one of the high voltage terminals leaked oil
7. and not a moist insulation The owner wanted to seal the leak by replacing the O rings and corresponding gaskets and put it back to service Megger Sweden AB phone 46 8 510 195 00 Eldarv gen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 24 26 2010 01 05 MODS v2 0 0 0 File Configuration Diagram Automatch Help Power factor at 60Hz Model 0 423 CT1 AON 381 Geometry Barriers X 150 1 Iv Spacers Y 0 0 Iv Material 1 Material Cellulose Se Moisture 32 m Temp C 20 Material 2 1 3 Material Oil vi Permitivity 22 Conductivity 5 68E 12 j Tand and PF X 1 4573 Y 0 016328 Temp 1E5 0 001 10 1000 0 1 Frequency Hz Figure 20 IDAX Test on COF 350 with GS Template The unit presents a 0 387 PF at 60Hz which is still within acceptable values If this was the only available analysis then the PF test is just a YES NO test Let s look at all the information obtained from IDAX after the analysis with MODS Error Reference source not found summarizes the results obtained Moisture Content Oil Conductivity S m PF 60Hz Table 1 Summary of IDAX Test on COF 350 before opening the unit This test reflected clear contamination of the liquid insulation by ageing by products MODS v2 0 0 0 File Configuration Diagra
8. been used for the evaluation assuming existence of equilibrium in distribution of moisture between oil and paper pressboard but unless a direct sample is taken from the solid insulation this analysis will only reflect the moisture in the liquid insulation In addition for oil sampled at low temperature the equilibrium curves are not very accurate which additionally introduces uncertainty in the estimates of moisture content Failure of a substation type oil immersed current transformer can lead to a high energy explosion Because of the difference in thermal expansion ratio between the metallic housing of the CT and the relatively fragile porcelain insulator mechanical stress builds up that may result in a blast where fragments from the porcelain insulator may reach up to 50 m from the location of the unit Loss of this important device results in phase to ground fault that will trip the operation of a substation Reliability of the energy system is a consolidated value where major components and critical components should be evaluated A link is not stronger than its weakest link Megger Sweden AB phone 46 8 510 195 00 Eldarv gen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Application Information 4 26 2010 01 05 Figure 1 Failure of a Current Transformer of the Substation Type Certainly operators do not want to have a similar to Error Reference source not found p
9. grep ey ae a Oe ae Sale Clete diah fle shs oly al oh G eit clotted tel Pach iases sce p ssan Saco aal aa a a ease eee sis so ee eT oe ey ee ey Ce ee pt it Frequency Hz Crosse aa Aaa ar Press Senses pete Power factor at 60Hz AX Model abe emcee Oramo M 0 363 PO P ee M ciche Oke pees Mien OV a es Geometry im e CI M ean MDEE Barriers lt 70 8 Iv Spacers Y 2 9 vy Material 1 fal Uh tee ls alata led ode Ne aoe Temp C 20 Whee abe MMaterial 2 z ina Shan Noda ALAIN ba sae 3 Material Oil Y Permitivity 2 2 Material Cellulose z Moisture 1 3 all Conductivity 1 09E 14 j X y Temp mepe sSs Figure 17 IDAX Test on OSKF 72 5 An example of the advantage with frequency sweep vs PF at Mains frequency The PF is 0 339 this value is higher than the previous examples but the moisture in the solid insulation is only 1 3 and the conductivity of the oil is very low 6 4 CT OSKF 245 0 3B1 8 10L800 RF 1 0 MODS v2 0 0 0 File Configuration Diagram Automatch Help Tand and PF il Frequency Hz PF a Power factor at 60Hz 0 238 1000 Model abe z m e lPF OTango E Barriers X 49 6 Iv Spacers Y 4 1 Iv Material 1 i Material Cellulose J Moisture 1 3 Iv Temp C 20 Matei 2 Material Oil 7 Permitivity 22 Conductivity 1 08E 14 7
10. housing Bushing tube Primary insulation Head housing Expansion chambers Primary conductor assembly Porcelain shell Base assembly H1 primary terminal Oil to air seal block E E 8 9 10 14 12 IA Secondary terminal box FEY Oil level indicator Portland cement bond 15 Active part support stand 16 Secondary leads Ground pad Optional ground fault CT 19 Optional capacitance tap ea _ Figure 8 Type OSKF Oil lmmersed CT by Trench 2010 01 05 The custom designed toroidally wound cores are located in the head of the unit The core housing can accommodate up to six independent multi ratio relaying cores or a combination of relaying and metering cores requiring up to 30 secondary leads The previous figures reflect the typical Trench Group designs for CT s from 72 5 to 800kV the following design Error Reference source not found 1s a more conservative design used for voltages from 25kV to 230kV The IK5 head type design below is hermetically sealed using nitrile rubber gaskets Normally this design will incorporate a dry nitrogen cushion above the oil to compensate for oil volume changes All these designs are single core with dual ratio tapped secondary winding Megger Sweden AB phone Eldarvagen 4 email 187 29 Taby website Sweden 46 8 510 195 00 info paxdiagnostics com www paxdiagnostics com www megger com Megger Primary Winding Primary Terminal Graded Insulation Syst
11. to noise interference and or spurious currents can be eliminated by selecting File Edit Values Megger Sweden AB phone 46 8510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 20 26 2010 01 05 MODS v2 0 0 0 File Configuration Diagram Automatch Help Ctri N New Model Curve Open Measurement File Ctrl 0 Report zz Save curves Ctrl S pa Export curve a Remove Curve gt Edit Values gt Exit Pp techateee tl peta Heatly crore a Cty fy beet l gedaan it Selly fy eet pes bate Fad poy oh 9 a fed pedis iy ey ae It ptf tees ple PELs E ET N GRA P E E EE POT A P E O OEE TE E e p B A E S T A E E Wide E E cad Model cT1gs sh Satta lietated Cath EEE E m e PF Orma M n Auto match _ CT19s M Geometry o Barriers k3 Vv oe Spacers Y o Iv Cellulose v Moisture 3 IV Temp C 20 Material 2 pace Material Oil v 22 6 5211 fy 4 Material 1 Material 465 lt 4 bP Permitivity Conductivity CrssSas lt x a 3 PEPO E mea Re Hee N ar Ut a T E E O AE LA hat E E T E 1 Frequency Hz 4 Classification cE WO 1235 AM For validation of the results and better understanding of possible moisture increase within the insulation system aged units presented values of 4 and above Therefore it i
12. 022 0 01 0 Min Max Specimen capacitance 10e 12 10e 6 Maximum DC current 1e 6 Maximum Hum current 500e 6 Notes Follow local safety regulations Make sure that both preparation procedures described below have been made Preparation Procedure IDAX Instrument 1 Before connecting the IDAX instrument power cord to mains outlet Connect the Transparent ground lead to a protective earth ground close to measurement specimen and to panel of instrument 2 Connect the IDAX instrument to a mains outlet that fulfill requirements in the users manual x Input the information and you are ready to start the test with your IDAX 300 Select highlight the actual test file GST Start measurement 3 Moisture Analysis Megger MODS is used for the moisture analysis For details on the program and insulation modeling technique please see the MODS User manual 3 1 Step by step procedure Open the Sweep you want to analyze Right click on the label and select send to MODS Results File Edit Diagram View Configuration Help sl Gil PES 4 t HMO_TSP COMODIN 2009 08 27 TSP COMODIN 2W CH ch MQuick Test Measurement Data Graph Table 60Hz Data Test Capacitor K Gi Model Transformer CH Two Winding Transformer CT_application_note C HMO_CFE CT and PT t 3 z iz HMO_TC NUM SERIE U 140 VY RMS Stopfreg 0 02 Hz I On
13. Megger Sweden AB phone 46 8 510 195 00 Eldarv gen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Application Information 6 26 2010 01 05 Figure 4 5kV Dry type solid cast CT 1 3 3 Type COF Outdoor Oil Filled Wound Type Metering Relaying CT 15 25 34 5 46 69 115 138 161 kV Figure 5 69kV Oil filled Wound Type Metering CT The tank dome is fabricated from carbon or stainless steel depending on current rating The units are pressure and vacuum tight and hermetically sealed at the factory to prevent breathing and oil contamination Tank components are washed and coated with anticorrosive iron phosphate and then finished with ANSI 70 Gray baked on electrostatic polyester powder The bushing is high strength porcelain with a high degree of stability for transportation and seismic withstand RF up to 1 5 Megger Sweden AB phone 468 510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 71 26 2010 01 05 1 3 4 Type CA Outdoor Oil Filled Wound Type Metering Relaying CT 230 345 500 765 kV _ _ _ _ TORR Cn Figure 6 Outdoor 230kV Oil filled wound Type Metering CT This specific design is for Voltages of 230kV and over The tank dome is fabricated from corrosion resistant aluminum and contains stainless steel expans
14. a reason to remove the unit from operation Normal construction of CTs does not provide piping valves and fittings PV amp F for oil filtration 7 Conclusions TBA 8 References 1 Molded Wound Type Instrument Transformers Available from https www kuhlman com clientdata MV WoundBRIMVW0502 pdf 2 46000 Volt Instrument Transformers Available from https www kuhlman com clientdata 46000voltsection pdf 3 5000 Volt Instrument Transformers Available from https www kuhlman com clientdata SOOOvoltsection_intl pdf 4 69000 Volt Instrument Transformer Available from https www kuhlman com clientdata 69000voltsection_intl pdf 5 500000 Volt Instrument Transformer Available from https www kuhlman com clientdata SO0000voltsection pdf 6 Current Transformers Type IOSK Available from http www cotecsa es images cot E217 11 A4 pdf 7 Current Transformers Type OSKF Brochure E217 21 05 2006 www trenchgroup com 8 Current Transformers Type IK5 IM IH Brochure E217 31 05 2006 www trenchgroup com 9 Gas Insulated Instrument Transformers for Outdoor Installation Brochure E216 11 05 2006 www trenchgroup com Megger Sweden AB phone 46 8510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com
15. em Secondary Terminal Box Ts H AVA Application Information 10 26 2010 01 05 Core With Secondary Winding Marine Grade Aluminum Expansion Chamber Wy A d A OE J Z LE aia Pras A IR AD WL bales fe A ii DN D SS eee Le Pf SS S h Ae Figure 9 Typical IK5 Oil lmmersed CT 1 3 7 Outdoors Gas Insulated Current Transformers These units are available for voltages from 72 5 to 800kV SF6 has been recognized as a non toxic inert and non flammable insulation medium Therefore SF6 compressible insulation medium is an explosion proof design According to manufacturers these units have no insulation ageing and a minimum risk of failure Gas is monitored by a density meter guaranteed SF6 leakage rate of less than 1 per year Transformer operates at rated voltage even in the case of loss of SF6 pressure Head type Gas Insulated Current transformers are found in the market for primary currents in the range 100A up to 4800A Core changes after assembly do not require the destruction of the high voltage insulation Megger Sweden AB Eldarvagen 4 187 29 Taby Sweden phone 468510 195 00 email info paxdiagnostics com website www paxdiagnostics com www megger com IVI eg er Application Information 11 26 2010 01 05 i ne Rupture Disc in a H Primary Conductor a 3a Secondary Housing 4 CT Cores 5 Head Housing
16. en AB phone Eldarv gen 4 email 187 29 Taby website Sweden 46 8 510 195 00 info paxdiagnostics com www paxdiagnostics com www megger com Megger Application Information 16 26 2010 01 05 New Object Object and Measurement Title Test Object Template C Documents and Settings m Browse Object Name Enter name that is easy to remember Associated Measurement Templates MeasurementT emplates 2W CH ict Af Ok X Cancel When the Object has been created fill all fields with requested name plate information This screen allows you to include comments regarding the unit ex File Edit Diagram View Configuration Help oid HID T ES l f CT_application_note MQuick Test Object Graph Table 60Hz Data Test Capacitor C Model Transformer General specimen data i TIC a Company My Company Division Location E HMO_TC NUM SERIE U0047 3 Mfr XYZ Year of mfr 2009 Serial No oox HMO_te u 0047_2 a HMO_tpe serie MM03000 1 kv Type MVA HMO_TPI 13 8 KV HMO_TSP COMODIN Comments HMO_U 0047 2 Go to File New Measurement Sequence and provide the data requested Make sure you have entered the average insulation temperature Your menu will have now all information ready to initiate testing Megger Sweden AB phone 46 8510 195 00 Eldarvagen 4 email info paxdiagnostics com
17. icture taken in their facilities Maintenance in the electrical industry and especially in the transformer business is moving from a Preventive Programmed Maintenance to Condition Based Maintenance and new technology is now available to operators for a better assessment of such valuable devices 1 3 Construction of Current Transformers 1 3 1 Outdoor Molded Epoxy Wound Type Metering Relaying CT 15 25 34 5 46 69 kV The core and coil assembly is wound and encapsulated in a high dielectric strength epoxy resin to provide high withstand capabilities The external line to ground insulation consists of a cycloaliphatic epoxy resin that provides excellent arc track properties in addition to UV resistance and strong physical strength A high voltage stress ring around the top of the unit is supplied to limit corona Megger Sweden AB phone 468510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 5 26 2010 01 05 Figure 3 Outdoor 46kV Molded Epoxy Wound type Measurement CT 1 3 2 Outdoor Molded Resin Window Type Metering Relaying CT 5 8 7 15 25 34 5 kV This is a dry type solid cast CT able to operate with high accuracy for metering or relay applications The core and coil assembly is wound and encapsulated in a molded cast resin with a standard 4 44 window to provide high withstand capabilities RF up to 4 0
18. if the unit has not been in operation recently insulation temperature is assumed to be the same as ambient temperature Figure 12 Secondary winding in GST General Specimen connection Megger Sweden AB phone 46 8 510 195 00 Eldarv gen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 13 26 2010 01 05 Recommended test setup is GST Grounded Specimen Test applying test voltage to the HV terminal LV terminal should be grounded See figures 11 to 14 HV Terminal b E LV Terminal om Figure 13 GST without guard Megger Sweden AB phone 46 8 510 195 00 Eldarv gen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 14 26 2010 01 05 HV Terminal Figure 14 Measurement CT GST with guard connection 2 2 Step by step procedure In order to measure and analyze an oil immersed current transformer the following steps should be followed Start IDAX Control and go to the application Result Go to File New Object Megger Sweden AB phone 468510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 15 26 2010 01 05 Edit Diagram View Configuration Help Measurement Sequence Object Quick Test Add Re
19. ion bellows to allow for the expansion contraction of oil for temperature and load fluctuations The bellows maintain constant pressure on the oil under various ambient and load conditions to allow for horizontal shipment Base components are shot blasted washed and coated with a heavy galvanized finish The primary bushing is ANSI 70 Gray high strength porcelain with a high degree of stability for transportation and seismic withstand An adjustable primary spark gap is provided for all units to protect from high transients The unit is fitted with an oil level indicator and oil sampling drain valve The unit can be manufactured in single dual or multiple core design RF up to 4 0 1 3 5 Type IOSK Outdoor Oil Paper Insulation Current Transformer Head type design of low weight and minimum oil volume These units have good seismic performance The primary could be of the bar type or bare conductor type sized properly to withstand short circuit currents and to avoid large voltage drop across the primary winding The secondary winding is distributed uniformly in order to obtain accurate transformation These units provide stable accuracy over long periods of time Expansion bellows are located on the top of the unit to allow oil expansion Megger Sweden AB phone 46 8510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 8 26 2010 01 05
20. l cdl ohh ea Tand and PF 0 01 et ee re ee ee i p E Pt t tad tae tke hel al oie fet eb Fett hated oant baa chal ge bal ty betcha ated Sota Fela eer aks ol ah be a aan ches okey bake ie ne bel rl oh eect etal ota tte 1 Frequency Hz Power factor at 60Hz EE E T E L a A aaiae salala pra are EE EA E E DEET A TEE E A E E E E E E E E E i E EE ER E E Er E o E E O E O EL y E E SE A EEE S EE ees m Model abe m s PF Ofang0 E Auto match fave v Geometry Barriers lt 39 4 TA Spacers Y 3 1 Iv Moisture 2s Iv Temp C 20 Material 2 Material Dil ad Permitivity 22 z Conductivity E7014 K Y Temp Material 1 Material b gt a a6 Figure 16 IDAX Test on OSKF 123 6 3 CT OSKF 72 5 0 1PL335 1250 1 Megger Sweden AB phone Eldarvagen 4 email 187 29 Taby website Sweden 46 8 510 195 00 info paxdiagnostics com www paxdiagnostics com www megger com Application Information 22 26 2010 01 05 MODS v2 0 0 0 File Configuration Diagram Automatch Help eed getty ate oad rit ot hel oh be tte Ratan Nady bated adel pel ota So che fy le tte pada fey be lis le ct oh fe tet ite sone eda tn te Pol ol tea te vote a al be al daaa aan tale oil ae tal ot b feted lata tobe toed cet otra oh ty betel a etek to cal ah ha G eta tetas A teat Tand and PF 0 01 ee ee E E A E ET oe Sy ere eee Se S
21. ly 50 60 Hz HMO_te u 0047_2 41 2 HMO_tpe serie MMO3O im Mag fe HMO_TPI A3 8 KV Specimen capacitance 40e 12 8000 9 HMO_TSP COMODIN 2 2009 08 27 TSP Cl Maximum DC current 1e 6 A E 2w CH p p L Maximum Hum cyrrent 500e 6 py 2w Send to MODS E zw D 2w Change Sweep Color HMO_U 0047 Follow local safety regulations Make sure that both preparation procedures described below have been made Connect the Ground lead Transparent to ground Connect the Current Sense 1 lead to the low voltage winding Connect the Generator lead Yellow to the high voltage winding Remove ground connections from all phases Press the software Start button to start the measurement Wait until measurement has finished or abort earlier by press the software STOP button aR Gmail Inbox 1 d p DFR Current Transfo Ty IDAX Application G IDAX System Control Confirm change enter the insulation temperature Megger Sweden AB phone 46 8510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Tand and PF Megger Application Information 18 26 2010 01 05 The temperature parameter is setto Celsius 40 erity the temperature 40 Fress OF to set the temperature forthe model curve Cancel Select CT material database We recommend that you Confirm change the default automatch se
22. m Automatch Help Model cTigs _x PF 3 a Power factor at 60Hz lt m e F Dlengo F Auto match jer gs gt Geometry Barriers X 51 Iv Spacers Y 5 0 Iv m Material 1 Material Cellulose Moisture a4 iv 2 eas ia Tempt 20 7 a emp C Material 2 gt Material Oil ball so Permitivity 2 2 l Conductivity 1 04E 11 X 82 84 Y 0 073207 Temp 10 100 1000 Frequency Hz Figure 21 IDAX Test on COF 350 after terminal replacement connection GST Megger Sweden AB phone 46 8 510 195 00 Eldarv gen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 25 26 2010 01 05 After replacement of gaskets and O rings of the high voltage terminal the value of PF increased above acceptable values Oil conductivity and moisture content also increased This example clearly shows the benefits of using the wide frequency sweep instead of only one power frequency reading The unit was opened and the failure fixed Now the owner wanted to identify how this work affected the unit Therefore the same test was carried out following exactly the same procedure Again the insulation diagnostics device provides specific location of the possible contamination As a matter of fact the oil exposed for a long period of time to the atmosphere absorbed the moist
23. move Templates 60Hz Data Open Measurement Close Measurement Re A 1 Create new Measurement Sequence 2 Select desired Measurement Templates S s 3 Start measurement according to chosen Measurement Plan I Load D file Ctrl L Import gt Export a Rename File Folder Delete File Folder Exit Gmail Inbox 1 d FDS Application not IDAX System Control lt B BO 11 20Pm A New Object window will open for you to provide the main information of the unit Click Browse to select the CT object template New Object Object and Measurement Title Test Object Template Object Name Associated Measurement Templates X Cancel Look in le ObjectT emplates i E m Autotransformer without R NIOuick Test obj F E Bushings obj ITeskt Capacitor obj m lgeneral Specimen obj E m Autotransformer with Tertiary Bushings obj m Motaatbj m Autotransformer with Tertiary obj m PILE Paper Insulated Lez m Autotransformer without Tertiary Bushings obj m Three Winding Transformi lt ii gt Files of type Object Templates obj Cancel File name File information Date es eee Title Current transformer Object m Description Object template Name the object using a name that is descriptive as this is the name that will be seen in the object browser Click OK to create the object Megger Swed
24. per insulation Current Transformet ccccccccececeeeeeeeeseeeeeeees 8 1s Outdoors Gas Insulated Current TransStOrme rs ws 2i cascicsaecscscesasannaaaneadtndeccanetssssaseareiaaanaaadiectegas 10 2 DFR measurements on Current T PANS OPIMGES o5c0ia ci scsoceccsdsnnnecaiadsestasmaasoneaonsinssssaGacaseteataneneesseuesuaeseunsosiacs 12 2l K Mb ye CUO E S E E 12 22 aceasta A TEE ce anion AIEE E TEN E T ca tench 14 F Montre Ani ee a RES a E aai 17 3 1 eo oea A I E cas neue E A E E E E eam ecaiaannaandaieemnencineasse2 17 i Comments on IDA X measurements on CTS sss ca seacicnceataracesaastesvagsassdunccadsvacnatadenadeashidiosansssasenoiacusics 19 NIC MO race cence E R E E OA E 20 Mya E R 20 o 2G 2 Ug If Bh e E a E 20 6 1 RO SO SB 200 TE LA eenen E 20 o2 CT rOSEFP COICO C OU RF T pn poner tsa eat enews enero ranean 21 6 3 CEOE eg Ns ee E n ae ee iene oe een re nny mere yee rte Sere meaner eee 21 OT CT TOSKA Se 7 OL GUO IR LUi E 22 6 5 CrO CELERE LS REZI emery or eee erento aa ter Sanne eneT wey 23 o0 COF OCTO BES RFL 2 e a A 23 E E A AE EEA AA A A EA E A O E A A 26 BS ie a reece rs A eg O E A EA arena anise ce es E E ESA A E EE TE 26 Megger Sweden AB phone 46 8 510 195 00 Eldarv gen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 3 26 2010 01 05 1 Medium and High Voltage Current Transformers 1 1 General Information Design features of Current T
25. prevent this is to make sure the unit is dry and cleaned before the test Recording ambient temperature and humidity 1s always recommended in case the analysis is questionable Measuring GST guard using a conductive collar strap can also reduce leakage currents on the outside enclosure of the tested device e The conductivity of the oil reflects the degree of ageing of the unit and the subsequent contamination due to the byproducts normally obtained from the cellulose and liquid degradation A brand new transformer typically has oil conductivity in the E 15 range Therefore if any characteristic is moving below this range set the Oil Conductivity to 1 00E 14 and uncheck the checkbox next to the oil conductivity field e A conductivity value above 5 00E 11 is an indication of carbon sediments and overheating of the solid insulation e Moisture in the solid insulation is temperature dependent Make sure to correctly estimate the test objects temperature Refer to your manufacturer manual for the heat run test analysis that can provide information about of the expected temperature at certain load levels Best scenario of course is to allow for cool down to a stable temperature prior to running the test e Current transformers are available in different types and constructions but they normally have an oil level gage Confirm that the oil level in the tank is ok e Some test sweeps are more difficult to analyze than others Out of bound values due
26. ransformers at Medium and High Voltage levels need to be briefly reviewed for further understanding of the use of IDAX to diagnose the insulation system of these devices This document discusses the application of testing techniques to oil immersed current transformers of the substation type Current Transformers CTs are critical components within the electrical infrastructure The electrical Industry whether related to generation transmission or distribution of electrical energy requires of CTs for the purpose of measurement and protection Even though these devices are used for protection of major components of the system and to provide continuity of operation CTs are not protected by any local or remote monitoring instrumentation Therefore testing of these critical components by reliable technology as well as a proper understanding and interpretation of results is of major interest for manufacturers and operators worldwide In this application note some of the most common designs are briefly described and testing analysis is presented exclusively as applied to Current Transformers of the Oil Immersed type of insulation 1 2 Risk of Unknown Conditions during Operation Accurate evaluation of moisture content in the oil paper insulation system of instrument transformers is a concern for many utility operators worldwide Water significantly accelerates ageing of cellulose Oil analyses by means of Karl Fischer titration KFT have traditionally
27. s suggested to consider the following values for reference 5 Accuracy Compared to moisture assessment in oil immersed power transformers moisture estimation in CT s is a relatively unexplored application However the basic theories on insulation modeling are well proven and there is no reason to believe that this application should be significantly different from the power transformer application The accuracy in moisture estimation in oil immersed current transformers head type is estimated to 20 of reading 0 2 for moisture levels 1 4 and insulation temperature 15 40 C These numbers can improve as more measurement data and laboratory results are added to our measurement database 6 EXAMPLES 6 1 CT OSKF 123 0 3B2 0 C400 RF 1 2 This unit has a power factor value 60Hz of 0 19 and the moisture content is 1 5 Conductivity of the oil is very low which indicates a good dielectric breakdown value and no by products contamination Megger Sweden AB Eldarv gen 4 187 29 Taby Sweden phone 46 8 510 195 00 email info paxdiagnostics com website www paxdiagnostics com www megger com Application Information 21 26 2010 01 05 MODS v2 0 0 0 File Configuration Diagram Automatch Help Model abc Frequency Hz S Mc PF OTango EJ Auto match fave x Bares ba fer Spacers Y 4 2 V er E Material Cellulose x Moisture 1 5 V Tempt
28. tin A aR RS NE rae aim eo OMS moe EE T RA AE T I AI ats KT or Pies 6 Rempel tee ot E GA BAY Ft p oa e Bamana eee a Lv see coeds Lape est al el raat th pagent Pail poi rickets oe tabntt SS Nee See a rg a ee y ae ee ee TE ee ee oS ae oe ey ee ee yee ee an ie mn 0 001 e e e E EA ar a E A a E A E aan E ea e a E aE E E a aa A E a p e E A e EE PEE PE E PED E E EE K EE 0 001 0 01 0 1 1 10 100 1000 recquenee Iz Figure 22 IDAX Test of COF 350 after filtration process connection GST Moisture Content Oil Conductivity S m PF 60Hz Table 3 IDAX test on COF 350 after filtration process The tested unit shows improvement and acceptable parameters to get back into operation Megger Sweden AB phone 46 8510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com Megger Application Information 26 26 2010 01 05 Experience gathered through experimentation indicates a range of moisture concentration between 0 5 2 0 in new CTs after factory test Power factor values as presented in international standards will vary in a range from 0 2 to 0 25 in brand new transformers and this value will increase with ageing of the units due to gas evolution and degradation of the insulation system In accordance to standards a value above 0 5 PF at the power frequency calls for additional testing procedures and a value above 1 PF is
29. ttings when you use MODS for CT analysis If you only analyze CT s you can leave the settings like this File Configuration Diagram Help X amp Y Settings Model ch Oil Condictivity Settings A E re E E RERET E e PF Orago CO Settings i i i a Auto match fen gt A Palette ats betaine otis Cores fate et bol phy btn cate ot ently aeia ental ais tte ole Joe Nl ot a nah aan tol ated oe alana tail aaea fata Lele ake fate iah da a peat tal i ae i i oi ceon a 1t iig si 22 szi sbededetehezzzz Bamers lii j20 0 M PEERS Spacers Y 20 0 Iv EAr EEE E Saas Faces st seter gee de Tasio e T E r E E T S E E EEE A E r a E aS aoe See nent 2 gt a a r r i Material Cellulose v Sgn pon a a asa aie ies Moisture 1 0 Vv ee a ee eee ITem fa m Material 2 Material Dil z7 Permitivity 22 pastel i ae mai nea ae ic ie sia Conductivity 1 00E 12 M C a DUENE UME a obp l v au senen ae aoe ae cs ed x Hae 4 4 y Temp 0 01 cert possess EEEE ei Aate pege aad edited tad belaia Tata ia a ball chs bala oaa CSS a adel Heated tad feted ke take oh el cela 10 Frequency Hz gt 5 Gmail Inbox 1 Ty DFR Current Transf Ty IDAX Application IDAX System Contr Mods lt Be fa WG 12 04 AM Auto Match Settings Dil Conductivity X amp Y co amp Y range v must be be
30. tween 30 And E V Y must be between fo And 5 Restore defaults Set as defaults OK Cancel Do not forget to change back before doing moisture analysis on power transformers Click auto match in the main screen Wait for the curve matching process to finish Read moisture level Below example show 2 4 moisture Megger Sweden AB phone 468 510 195 00 Eldarvagen 4 email info paxdiagnostics com 187 29 Taby website www paxdiagnostics com Sweden www megger com File Configuration Tand and PF aces eee Sy er ey eee Pa Application Information Diagram Automatch Help pasctiteviss ld sadn etd EAEE EN sofa eee AE t E AERALA EET te igs Power factor at 60Hz r E ERRERA E SAE 0 412 0 412 zx Model Jen 19 20 2010 01 05 cme el orango W Auto match fon gt Teeni Barriers X 2 9 Vv Spacers 7 5 0 Vv Material E Material Cellulose Moisture 2 4 Vv Permitivity Conductivity Oil Temp C 20 MMaterial 2 J Material 46254 2 Pe 22 140E12 f X Yes T 1000 1 Frequency Hz 3 2 Comments on IDAX measurements on CTs e GST measurements have been selected since many CT s do not have a test tap GST measurements are possible to perform on all types but have the disadvantage of being sensitive for leakage currents on the outside of the unit Normal procedure to
31. ure and this is perfectly reflected in the test Then the physical problem was fixed but the unit cannot get back to operational conditions Then why is someone going to do that A summary of the results is presented in Error Reference source not found Table 2 IDAX test on CT after replacement the damaged HV Terminal Let s look at the readings after heating and vacuum filtration of the liquid insulation MODS v2 0 0 0 File Configuration Diagram Automatch Help i S Am ot Jac eE e E E T EOTF omc el orso W abc 0 38 Bees ero Posey ates ct ae Fol a fy hace Rt etait bd bae tel a Wd ria Br lactate aar fetal Sal pate ake te Heal eel pl Prt Hada CoE een ol VP TA Mecca aA i teed en AA TL See te tole pital oaks Weds Ym fod P aeda tee a Se a oe G er Barriers X 44 9 Vv p aS lt a aa Spacers v 50 m Material 1 4 SO ea ee 7 t 1 Sss Material Cellulose aaa ea ae yr a a ar W Ba i eae i Moisture 3 1 m T A ee i NPY TE a is Ye hee aces ee Teme 2 Material 2 iW Seed ee t L t Red 4 cess Material Oil Permitivity 22 e RERS Conductivity 4 62E 12 Tand and PF pre tt S rots e E E a lait a are aa pete Gea pela fanaa E d i A aa 10 E ri oOo Vit Pobre oo tit _s r Pod ot E Jis nvs D oa ot Y Temp a Sa ee is Dias iis No ke A AO NE ea oR eet ar es rahe a Saka DBs EE cle ms DS aioe Maw
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