Home

MicroTech Control System for Air

1. ari DAI s Low Linit far Mir Lit SPT a 10088 99 2 25 909 1005 Cm press Capacity Lift Pressure Dead Band The MicroTech controller establishes a dead band above the minimum lift pressure that varies with circuit capacity If the lift pressure is within the dead band no fan staging will occur Condenser fan staging will occur as follows for lift pressures above or below the dead band Table 17 Condenser Fan Staging With No SpeedTrol Dead Band Table No SpeedTrol Unit Capacity Staged Stage Stage2 Stage3 Stage4 Stage5 Stage6 1005 120 100 60 40 25 2 505 6 50 3 20 15 15 15 Table 18 Condenser Fan Staging With SpeedTrol Unit Capacity Stage0 Stage Stage2 Stage3 Stage4 Stage5 Stage 6_ 255 3 20 0 0 10 Fan Stage Up Every four seconds the controller records the difference between the maximum condenser pressure as defined by the minimum lift plus the dead band and the actual condenser refrigerant pressure This value is added to the previously recorded values and when the accumulated total is equal to or greater than the stage up setpoint the controller starts an additional fan stage The accumulated total OM ALSMICRO 29 30 is set to zero whenever a fan stage change occurs the condenser pressure falls inside the dead band Fan stages 5 o
2. 2Curr Alarm SeestCurAamAbwe 1Prev Alarms tsameasmenu25 2 rhrmmm dyy s psameasmemuzat 4 2 5 j ssameasmmuzt 6 j 9hrmmm ddyy 4 same as menu 24 4 hr mn mm dd yy OO p 60 5 hrmn mm dd yy 2Prev Alarms See 1Prev Alarms Above Td OM ALSMICRO Menus for Three 3 Screw Compressor Units Table 31 Three Compressor Menu Test Software Menu Display Defaut T Ambienlck 21 12 9009 Waiting fortoad L A Cose Cose 3 4 Table 32 Three Compressor Menu Status Menu Display Defaut Range Circ 1 Status Off SystemSw Off ManualMde Alarm Off CycleTime _____ JOf PumpDwnSw j WaitFlooded Starting Pre Purge o O Opened LowAmbStat Pumping Down Circ 82 1 SameasCir tabove 1 Same as Cir t above 1 Water Evap F C 2 C 3 4 iva Circ Pres s 7 1 Evp psi kPa F C
3. EOF F Short F Subcool F F AF F OM ALSMICRO Capacity ll Fan Stage ExpV Pos 82 Curr Alarm f 1 Table Continued on Next Page Table 37 Three Compressor Menu Alarms Continued Menu 1 1 11 1Prev Alarms 2 mmiddiyy 0 2 22 Jihemnmmddyy W3Prev Alarms 2 _ 0 2Prev Alarms OM ALSMICRO 67 Menus for Four 4 Screw Compressor Units 68 Table 38 Four Compressor Menu Test Software Menu Display Range TesSotmae Of SysemSm Of Remote Comm Off RemteSw O Oft Time 7 Oft Alam O Off PumpDbnSws Off AmbientLck Starting Waiting Flow WaitingforLoad S O CoolStageUp o G O Cool Staging 4 O 2 nerStg se Holdstage min CT 1 4 Hi Loop Temp fi Table 39 Four Compressor Menu Status Menu Circ 1 Status tid C ftSysemw Off ManualMde Off PumpDwnSw Off CycleTime ft lWaitFlooded 1 OFF Ready Stating TC PreP
4. 4 CSCS nn 2 WaPevAams Si SSCS SSCS 2 mmddyy LL es E E F 31 mat 7 F w OM ALSMICRO Schematics Drawings Table 45 ALS Schematics amp Diagrams Control Wiring Unit Stage MicroTech Field Cabinet Legend Control Output Schematic Wiring Layout ALS 070A 100A Control Cabinet Layout ALS 125A 204A 588 071744901 REV ALSMICRO 77 Control Cabinet Layout ALS 205 280 EE 55152 lt lt 2 FEF FEB m 0 J He E 1 1 OM ALSMICRO ALS 125A 204A Unit Control P s 15 F NOR ile C a ri FOR FELD WIRING HIR 5 ANCHHER 24VAC POWER TC DIGITAL NE DU E POWER COMER SOL RELAYS 875 SURGING SCHEM LINE 8415 146 125 ESI NES aie l t CREAN 1 1 T 1 2 Ml TRUM 1 le BOON IDIOT Ci 120 7 FOR EXANEION VAIVE BOARD 896 SH MCRCIRCH ACHIA UNE 2332 MART 1 elt EN 010718596 ALSMICRO 79 80 ALS 205 208 Unit Control ALSMICRO ALS 300A 425A Unit Cont
5. Part Number 573865Y Effective March 2000 Supersedes IM 549 1 Group Chiller MicroTech Control System for Air Cooled Screw Compressors Models ALS 125B through 425B SYSTEM SWITCH AUTO w 1999 McQuay International CIRCUIT CIRCUIT NO 1 NO 2 AUTO AUTO PUMPDOWN PUMPDOWN STOP AND STOP McQuay Air Conditioning Table Contents Introduction General Description Control Panel Features Controller Layout 3 4 4 Software Identification 5 5 Component Data 6 8 Sensors and Transducers Standard Sensors 8 Optional Sensor Packages 8 Thermistor Sensors 8 Pressure 10 Liquid Presence 10 Sensor Data 11 Sensor Locations 11 Digital Inputs 14 Optional Analog Outputs 15 Digital Outputs sse 16 Installation 18 Unit Sequence of Operation 20 Compressor Control 21 Compressor Staging Control Sequence 22 Fou
6. Display Defaut Range 1 Curr Alarm Nm a HiPresStageHid r O HPresstagp TTT FreezeStageDwn LossdOnWFow 11 10 CamPumpow NoStattoEvap q _____ o oS SS FreezeStatProt O LoEvapPress O Motor Protect Repower a loss p pL S No CondWatFlow NoEvapPresDrop Below Min Lift P OM ALSMICRO 57 58 Table Continued Next Page OM ALSMICRO ALSMICRO Table 30 Two Compressor Menu Continued Menu Defaut Range 27 Moraan 000 Musa SOS Hghigressbop HibsmgTemp BadPhaseVols LvgWaterFreeze 9 hr mn mm dd yy 3 0 5 ITI 5 x gt eo 45 psi Openpsi Shortpsi Cond xx xpsi 50 psi Openpsi Shortpsi n a Open F Short F iquidLn xxx x F F F 0 c 5 x x Open F Short F XXX x F n a F Open Short gt 5 5 5 lt x 5 S S gt 4 Open Short X96 TI 5 0 Ent xd 18
7. Ice Mode The MicroTech controller has dual chilled water setpoints when ice mode is selected With an external reset signal of 4mA or less the chilled water reset will be zero If the external reset signal is greater than 4mA maximum reset will be in effect The following set points should be adjusted to accommodate the reduced ice mode system temperature and pressure Table 15 Setpoint Monitors A pressure value equivalent to the FreezeStat Low Evap Pressure 54 psig leaving solution temperature minus 10F temperature value equal to the leaving Preezel120 Leaving Solution solution temperature minus 4 A pressure value equal to the StpPumpDn Final Purnbdewn 34 psig FreezeStat setpoint minus 10 psi Note Once the load is satisfied in Ice Mode restart of chiller can not occur for 12 hours Network Reset The reset mode can be set to network if chilled water reset via communications network is desired The chiller controller receives a signal from the network master panel in the range of 0 to 100 of maximum reset Return Water Reset When return water is selected as the reset mode the MicroTech controller will adjust the leaving chilled water setpoint to maintain a constant return water temperature equal to the return water setpoint The return water temperature is sampled every 5 minutes and a proportional correction is made to the leaving chilled water setpoint The corrected lea
8. 5 TopSolnoid Compressor 1 6 Right Solenoid Compressor 8 Compressor 2 __9 Top Solenoid 22 10 Right Solenoid Compressor 2 11 Bottom Left Solenoid Compressor 2 12 Condenser Fan Circut M12 CondenserFanf2 Cicut 14 Condenser Fan 3 Circuit 1 M14 15 Condenser Fan 4 Circuit 1 M15 16 Condenser Fan 1 Circuit 2 M22 Condenser Fan 2 Circuit 2 M23 18 CondenserFanfS Circuts2 M24 19 Condenser Fan 4 2 M25 Off On 20 Liquid Solenoid Valve Circuit 1 21 liquidSolenoid Valve Circuit 23 Table 11 Digital Outputs 3 Compressor Unit 0 po hile Water Pump Relay 2 X k amp xvomo 83 ktXxvomo 4 Compressor tt Contactor 5 7 Compressor t Top Solenoid Vave 6 Compressor 1 Bottom Right Solenoid Valve feed 8 Compressor 2 Contactor 9 Compressor 2 Solenoid Valve feed d Compressor 2 Bottom Right Solenoid Valve feed r 1 Compressor 2 Bottom Left Solenoid Valve ven 42 Condenser Fan 43 Condenser Fan Contactor 4 455 Condenser Fan Contactor M5 16 Condenser Fan ContactorM 22 _ 48 Conden
9. rise above 5000 ohms the modem the 4 board just connected is defective With the power plug disconnected the resistance across an AOX 4 board s DC and terminals should not be less than 3 ohms Figure 17 MCB Power Supply Terminals Pwe F 1585 iBuss iac GDC T2 Fusazr1 gt 2 2 D 7 all AIX QUT A Troubleshooting Communications Problems If communications problem occurs check the following items Check the port B voltages Check the port B fuses gt Check the network integrity gt Check network addressing The best way to accomplish these checks is to perform the start up procedures as specified in the Network Commissioning section of the appropriate IM manual If these procedures have been performed and the problem persists obtain factory service Troubleshooting the Keypad Display Interface The Keypad Display Interface is connected to the MCB via a ribbon cable and discrete wiring for the back light The MCB provides operating voltages control signal outputs for the display and input conditioning for the keypad inputs Display is hard to read The clarity of the LCD display can be affected by ambient temperature Typically less contrast will result with cooler temperature If the display is difficult to read adjust the contrast trim pot which is located on the back of the keypad display assembly Back light
10. 1 3 _ 4 pu 5 EXV Postion amp et 6 Cond Fan Stage t px ALSMICRO 62 Table Continued Next Page OM ALSMICRO Table 32 Three Compressor Menu Status Continued Menu Display Range 1 Sameasabove 1 1 Circ 3 Press 1 Circi Temp s p 01 Satur Evap po eS SuctLine H F C C 3 Super heo 4 C 5 Liqidin HHAFFCO 6 7 Dschage 8 Temps 1 Sameasapoe Circ 3Temp s 3 Chilramp 1 parna 2 Pennan 3 CompRuntours SS 2 3 09700300 81 25 T 5 nosv we 6 f 75 EE ORE 1 100 8 2 25 x 41 9 2 50 x 42 75 HR I C j _ p 11 2 100 3 25 C _ 19 3 50 TP 3 75 iHHHHHE 3 100 lU Compr Starts 1 1 2 2 Total 3 MS Total en Airtemp 1 Outdoor t Table 33 Three
11. Alarm for detecting a unit that is low on charge Valid only at 75 Temp the monitor 5min is 100 load operation Liquid Line subcooling monitored and if a memory address below a default of 5F for 5 minutes then this alarm will occur Both the 5F and 5 minute timers are adjustable from the To prevent operation with abnormal low charge quantity HighLiqPress Manual Yes Hardware setpoint Hardware addition to send an open signal to Digital Inputs Drop 3 sys1 and 11 sys2 when a pressure differential charging awaiting valve psig LI psig exceeds 35 psig or what pressure is set hardware the switch Open condition must remain for 15 seconds before alarm i To prevent conditions where the filter dryer is clogged a liq inj solenoid fails or the liquid line shutoff valve is closed 27 Repower Auto No None If power is lost on running circuit then this alarm appears and logs a loss into buffer upon re power A 15min Off Cycle timer is activated Off Ready circuits are free to start at repower To help identify jobs with poor power supply 28 LoEvapPress Manual No Memory Address Protect in case of bad pressure transducer When the circuit is running and the evaporator pressure falls below 10 psig Pressure must remain below 10 psig for 30 Seconds Often 2 freezestagedowns will occur just prior to alarm 29 Hi Dschrg Manual No Memory Address Applies to compressor units only Alarm occurs when the Temp dis
12. ee P 2 606000000090 No s E _____ C Sos Yes no 4 Power Hz 16 5 6 Pre Alarm xxxxxx Binkopencosed jOATSeec ex Lc Yes 10 Opr xx Yes vYesNo 11 JvoEvpAdi F 0 3 3 8 8 1 12 EntEvpAdi F J 8 8 1 O 19 1EvpAdi psi J 4 431 O 14 2EvpAdi psi J 0 4 41 15 3EvpAdi psi J 0 4 47 16 1CndAdi psi 10 15 1 17 MeCndAd Hispsi J o 40 451 18 3CndAdi psi 19 Refrigerant R22 02 Must download correct code to change 20 IDENT SC 2X008 OM ALSMICRO 65 12 Date MWDDOYY Table 37 Three Compressor Menu Alarms Menu Tem Display 1 Curr Alarm LosohWFow _ CamPumbom 0 NoStartLoEvap WaerFresze OOOO BalwWaeSen LowSubcoolTemp 00000 9000 j 00000 A s L j me Rn F 5 Ewpigea open Bep SSCS 9 evap Ene 1 7 O 600
13. Low Pressure Transducer Circuit 4 High Pressure Transducer Circuit 4 Suction Temperature Circuit 4 Liquid Line Temperature Circuit 4 o 4 o N OM ALSMICRO 13 14 Digital Inputs Note All digital inputs are 24 VAC At 7 5 VAC to 24 nominal the digital input contacts are considered closed and the signal level is high Below 7 5 VAC nominal the contacts are considered open and the signal level i Table 6 Digital Inputs 2 Compressor Unit i 1 7 __________ Water Flow Switch Pump Down Switch Circuit 2 Reserved URNA EGET System Switch S1 Table 7 Digital Inputs 3 Compressor Unit Led On Alarm No Liquid Alarm Alarm Alarm 7 Normal Alarm No Liquid Alarm ff Not Used Remote Start Stop Switch Stop Evap Water Flow Switch No Flow PumpDown Switch Circuit 2 Normal 17 a ar Ala arm 1 High Liquid Pressure Drop 2 Alarm 3 O A No Liquid Alarm A A A larm i slow Normal Normal Normal Normal Run Normal Pumpdown Normal Normal Normal Normal Run Normal Pumpdown Led Off Normal Liquid Normal Normal 5 Normal Pumpdown Normal Liquid Normal Normal Start Flow Pumpdown Normal Liquid Normal Normal Normal Normal Normal OM ALSMICRO ALSMICRO Table 8 Digital Inputs 4 Unit Led Mechanical Hi
14. 52 Menus for Two 2 Screw Compressor Units 53 Menus for Three 3 Screw Compressor Units 61 Menus for Four 4 Screw Compressor Units 68 Schematics and Drawings 77 150 9002 43341413 McQuay is a registered trademark of McQuay International 91997 McQuay International Illustrations and data cover the McQuay International products at the time of publication and we reserve the right to make changes in design and construction at anytime without notice OM ALSMICRO Introduction OM ALSMICRO This manual provides installation setup and troubleshooting information for the MicroTech controller provided on McQuay air cooled screw compressor chillers Please refer to the current version of installation manual IOMM ALS for unit application information as well as water and refrigerant piping details All operating descriptions contained in this manual are based on the current MicroTech controller software version at time of publication Contact McQuay Technical Response Center at 1 877 349 7782 for information on specific code versions Chiller operating characteristics and menu selections may vary depending on the actual software version installed CAUTION This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instructions manual may cause interference to radio com
15. _ _ exl __ et 1 a 10 8 5 2 3 2 Voltage From ADX Board OM ALSMICRO Pumpdown Automatic Pumpdown As the system chilled water requirements diminish the compressors will be unloaded As the system load continues to drop the electronic expansion valve will be driven to 0 steps closed and the refrigerant circuit will go through a PumpDown sequence As the evaporator pressure falls below the StopPumpDownPres setpoint while pumping down the compressors and condenser fans will stop If the evaporator pressure is greater than StopPumpDownPres setpoint after 180 seconds have elapsed the compressor will stop and the display will read Can tPumpDown The alarm output will be activated Manual Pumpdown When the compressor is running and the circuit pumpdown switch is moved from the Auto position to the Stop position the circuit will pumpdown and stop when the evaporator pressure falls below the StopPumpDownPres setpoint When the compressor is not running and the circuit pumpdown switch is moved from the Auto position to the Stop position the controller will initiate a pumpdown only if the evaporator pressure is above the Begin Pumpdown Pressure setpoint The compressor will stop when the evaporator pressure falls below the Stop Pumpdown Pressure setpoint An additional pumpdown sequence can be performed by moving the pumpdown switch t
16. 18 4 50 M 75 e OO 20 440 100 2 CCS Wrtemp SSS e i hi Table 40 Four Menu Control Mode Menu Display Defaut Control Mode 22 0 2 7 Manual Unit Off Automate Manual Staging Service Testing o j Manual 06 OM ALSMICRO 6 Gre 4 Auto Off Table 41 Four Compressor Menu Set Points Menu Display Lvg Evap Spts values for R 22 refrigerant j Lvg Evap F C ResetOpt None None None Return 4 20ma Network Ice 9 MaChWRst HHF 210 0455 12 jOsIMeRst MAFF 60 00961 14 Amb Lockar 0 0601 7 AmbStage F 60 35401 SofloadSpts Tmetet mn 0 028461 7 4 loadDelay sec 15 02541 SE 1234 1324 2143 2413 3412 3142 a agp 1 2 10 x InterStg 6 j PrePuSp ffisec 0108266 Head Pres Spt MinLift 25 MinLift100 6 StageDnEr 50 300 10 Demand Limits 2 2 1 Demandlim sig 2 Time Date 7 1 _ 2 00 0 Table 42 Four Compressor Menu
17. 575 TO 203 230 SPEEDTROL TRANSFORMER 24 184 CONTROL TRANSFORMER 206 240 TO 24V OR 480 24V SPEEDTROL TERMINA BLOCK 120V FIELD TERMINAL BLOCK 24V FIELD TERMINAL BLOCK CONTROL TERMI 14AL BLOCK FIELD CONN LESS THAN ONLY TERMINA BLOCK MICROTECH ONLY TERMINAL BLOCK FAX ALARM TIME DELAY COMPR REDUCED INRUSH POWER WIRING FACTORY INSTALLED POWER WIRING FACTORY INSTALLED POWER WIRING FACTORY INSTALLED CONTROL BOX TERMINAL FIELD USAGE CONTROL BOX TERMINAL FACTORY USAGE COMPONENT TERMINAL INDENTIFED COMPONENT TERMINAL N ware Nut 6 MANUAL RESET CONTROL RESET CONTROL BOX POWER PANEL CTRL BOX KEYPAD PANEL INSIDE SPEEDTROL BOX CTRL BOX CTRL PANEL ON UCUD UNES ON COMPA UQ INJ LINE ON LINE TO HOT GAS VALVE CTRL BOX POWER PANEL BOX PANEL BOX PANEL BOX PANEL CTRL BOX CTRL PANEL BOX CTRL PANEL CTAL BOX CTRL PANEL BOX CTRL PANEL CTRL BOX CTRL PANEL CTRL BOX CTRL PANEL CTRL BOX CTRL PANEL BOX CTRL PANEL SHELOED AND PAIR de THERMISTOR 0006 t CAPACITOR variston v OM ALSMICRO McQuav Post Office Box 2510 Staunton Virginia 24402 2510 800 432 1342 www mcquay com
18. Schedule Menu item Display Defaut Rane Override tt Paw 3 Day _ 49 Sameas3above 110 Hox O 27 Holiday Date OM ALSMICRO 71 72 Date xxx 1 Dur Day s same as 1 and 2 above p o 1 1 Up to 14 Holidays Stored OM ALSMICRO Table 43 Four Compressor Menu Service Test Menu Display Defaut Range ServiceTest 22 3 2 0 0760 4 HGEXVPos HE 0760 5 0 0 6 8 7 Output5 xxx 9 OF 7 91 800utput 2B xxx 32 310utput 29 xxx 33 MS2Ouput3i xx 34 35 36 5 3 37 5 xxx 38 39 37 40 390utput 3B xxx_ 41 HMODHI HHHHHHHE 10101 42 101010 43 J MA2DHG HPHHHEHHE 10110100 44 43 45 455 Alarm 2 FullPumpDown xx No 6 ST _____ 21 ______ Table Continued Next Page OM ALSMICRO 73 Table 43 Four Compressor Menu Service Test Continued Menu item Display Defaut Range Mise Setup 1 2 5 SO SpeedTrol xx No Power z 6 50
19. s Bussman MCR 1 4 1 controller connection In order for the chillers and other level 2 controllers a network to connect and communicate with the level 1 controller is connected first 1 Set the network address to 00 level 1 See Addressing the Controllers above for more information 2 Push circuit breaker button to power up the CSC and verify that there is power to the MCB by observing the LEDs 3 Check the voltages of port on field wiring terminals 2 Use a DC voltmeter to test for proper voltages With the ground lead on the control panel chassis ground check the voltage at the and ground terminals Refer to Table 20 Port B voltages AMP type connector for the correct voltage levels If no voltage or improper voltage levels are found verify that the panel is energized 4 Plugthe network communication AMP connector into port B Level 2 controller connection This procedure will verify that proper communications have begun for each controller as it is connected to the network You can connect the level 2 controllers in any order however it is better to follow the daisy chain as you proceed This will make troubleshooting easier if communications problems occur As a result of the previous procedures the network communications connector should be disconnected from the B port at every controller on the trunk except for the level 1 controller Be sure that this
20. A is provided on the MicroTech controller for connection to an IBM compatible computer for local or remote system monitoring Belden 8762 or equivalent The network uses the RS232 communication standard with a maximum cable length of 50 feet All communication network wiring utilizes low voltage shielded twisted pair cable See the Personal Computer Specification section of this manual for specific hardware requirements Communication port B is used to link the unit controller into a MicroTech network using the RS485 communication standard Refer to the field wiring in this manual for details Modem Kit An optional modem kit may be installed for remote monitoring of the chiller from an off site PC running McQuay s Monitor software The kit comes complete with modem wiring harness and installation instructions Remote monitoring of the MicroTech controller requires a dedicated telephone line supplied by the equipment owner The McQuay Monitor software package used to establish a remote connection to the modem kit must be purchased separately Telephone line for remote modem access A voice quality direct dial telephone line is required if remote access and monitoring of the unit controller is desired The phone line should be terminated with a standard RJ 11 modular phone plug 19 Unit Sequence Operation 20 The following sequence of operation is typical for McQuay ALS air cooled chillers The sequence may vary depending on
21. During cooling mode if the Chilled Water Temperature is above the control band and the rate of temperature reduction is so great that in 120 seconds the chilled water temperature will be below the control band the controller will stage down The Project Ahead Calculation also moderates the controller s response to a rapid increase in leaving water temperature Interstage Timer The minimum time delay between stage up commands is set by the interstage timer setpoint default 120 sec The interstage timer for stage down commands is 1 5 of the stage up timer Anti Cycle Timer Anti cycle timers are used to protect the compressors from excessive starts and high motor winding temperature The anti cycle timers are 5 minutes stop to start and 15 minutes start to start 23 Lead Lag Refrigerant Circuits The following compressor control rules are enforced in the control software The MicroTech controller will never turn on the lag compressor until the lead compressor is at 75 capacity or greater and additional cooling capacity is required The MicroTech controller will not turn off the lag compressor until the lead compressor is running at 50 capacity the lag compressor is running at 25 capacity and a reduction in cooling capacity is required Three and four compressor units lag at 5096 before pumpdown Automatic Lead Lag The controller provides automatic lead lag of refrigeration circuits based on compressor operating ho
22. J 18 17 17 08 OT 19 H8Ouputi8S Of 000 20 f9Ouputi9 Oft 000 21 1820 0 1 101010 o O 22 21 DH2 10110110 23 22 OT Table 28 Two Compressor Menu Alarm Spts Menu Range StpPumpDn xogpsi 10 54 FullPumpdown xx Cd 6 LowSuboocxxcE S 0 ALSMICRO Table 29 Two Compressor Menu Misc Setup Menu 160 Defaut Range MiscSetup 5125 5140 Unit Type ALS155 q qUiType ALSiZ0 Unit Type ALS175 2 Unit 185 Unit Type ALS195 Unit 204 4 5 No 7 5 Powr xHz 6 5 6 Port A Baud xx_ 900 400 1200 2400 9600 8 Alarm xx Closed Closed open blink N O blink N C 9 OATSelectxx 12 10 AmbLockout xx No 7 12 LvgEvpAdjaxxxF 0 58 13 EnEvpAd cE 0 7 58 14 H EvpAdeeops 0 292 15 2EvpAdj xx xpsi_ 0 292 16 1CndAdj xxxpsi_ 0 88 17 HPCndAd xopsi __ 88 Refrigerant xx 22 134 407 Refrigerant type is not selectable on keypad new code must be downloaded 2 15 22 IDENT SC22U20NN 0 23 ReDate MMDDYY O Table 30 Two Compressor Menu Alarms Menu
23. Menu Control Mode Menu item Display Defaut Control mode Manual Unit Off Manual Unit Off Automatic Manual Staging 0 2 Manua Staget 0 02 ALSMICRO 63 64 Table 34 Three Compressor Menu Set Points Menu Display values for R 22 refrigerant Lvg Evap itit F C 6 MaxPullDn F C 20 541 7 ResetOpt None None None Return 4 20ma Network Ice Outdoor 8 ResetSig ma 9 JMaxchWRst r 210 04 5 12 MaxOaTRst HAFF o oo o 09 41 7 14 0 1 40401 AmbStage F p 60 30801 SofloadSpts 1 Timeleft min 0 0541 3 SoftldMaxSig 7 2 2 7 4 15 H mpressorSPT ea 123 132 213 231 312 321 2 InterSig sec 60 240 10sec jnteStgbv _ 15 1 210 4 8 8 15 540 imn 5 MnSPST MMmin 5 6 5 7 PrePurSp sec 1 Minuit 25 2 Minuit 50 3 140 101661 4 DeadBandMult 5 StageUper MH 6 StageDnErr i a Time Date 1 2 O Table 35 Three Menu Schedule Menu Item Dis
24. See Figure 3 ADI A good fuse will have negligible resistance through it less than 2 ohms If either or both fuses are blown replace them Go to step 4 If the fuses are intact the MCB is defective 4 Reconnect the Power In connector and disconnect all other connectors on the MCB Cycle power to the controller close and then open and check the power fuses If both fuses are intact go to step 5 5 If either fuse blows the MCB is defective Reconnect the keypad display ribbon cable if equipped with keypad display door Cycle power to the controller and check the power fuses If both fuses are intact go to step 6 If either fuse blows check the keypad display and the connecting ribbon cable for shorts Either one may be defective OM ALSMICRO ALSMICRO 10 11 12 13 Reconnect the analog input ribbon cable Cycle power to the controller and check the power fuses If both fuses are intact go to step 7 If either fuse blows check the ADI board the connecting ribbon cable and the field wiring for shorts Any of these may be defective Try repeating this step after removing or swapping the ADI board Reconnect the digital input ribbon cable Cycle power to the controller and check the power fuses If both fuses are intact go to step 8 If either fuse blows check the ADI board the connecting ribbon cable and the field wiring for shorts Any of these may be defective Reconnect the d
25. Select Menu 24 Two Screw Compressor Service test and with the Prev or Next item keys select the digital output you wish to test Enter the service password when prompted by the display Pressing the Inc key will turn the selected output on pressing the Decr key will turn it off outputs except 1 2 4 and 8 will remain in their last commanded state until the Service Testing mode is turned off Manually operating outputs 1 and 2 will drive the electronic expansion valve open or closed Compressor MCR outputs 4 and 8 will only remain in the on state for 15 seconds Exit the Service Testing mode by selecting the desired chiller operating mode from Menu 13 Two Screw Compressor Control mode Service Test Digital Inputs Select control mode Menu 13 Two Screw Compressor Control mode and set the chiller s control mode to Service Testing Select Menu 24 Two Screw Compressor Service test and the Prev or Next item keys select test 16 DHI The current state of the first 8 digits inputs 0 7 will be represented on the keypad display as a row of ones or zeroes where 1 equals on and O equals off By manipulating field wired devices system switch motor project etc and watching the keypad display the status of the first eight digital inputs can be verified Press the Next item key to select test 817 DH2 The current state of the second 8 digits inputs 8 15 will be represented on the keypad display as a row of ones or zeros wher
26. Thermistor Sensors MicroTech panels use negative temperature coefficient thermistor for temperature sensing normal sensor will measure 3000 ohms at 77 F Figure 8 Thermistor sensor Stainless steel tubing Potting 7 1 Thermistor 11 gt 8 OM ALSMICRO Table 2 Thermistors T Ohms volts Ohms Volts Ohms Volts 15 16104 4145 16 15627 4124 18 14720 4080 80 2789 2283 19 14288 4057 2 13871 4084 21 13469 4011 22 13076 3988 23 12698 3964 24 12333 3940 86 2416 2106 25 11979 3915 26 11636 3890 89 2251 2020 28 10983 3839 90 2199 1992 29 10672 3814 30 10371 3788 31 10079 3761 32 9797 3734 33 9523 3707 34 9258 3608 96 1914 1828 35 9002 3653 36 8753 3625 98 1829 1775 99 1788 1750 38 8278 3569 39 8052 3540 40 7832 351 41 7619 3482 42 7413 3453 43 7213 3424 44 709 3394 45 6831 3365 46 6648 3335 48 6299 3274 49 6133 324 5 591 3213 51 5814 3183 52 5662 3152 53 554 3121 54 5371 3078 55 5231 3059 56 5096 3028 59 474 2934 60 454 2902 61 4477 287 62 4363 28
27. down timer equals zero Max Pull Down The controller can limit the rate at which the chilled water loop temperature is reduced Whenever the rate of temperature decrease exceeds the maximum pull down setpoint no additional cooling stages will be activated 27 Condenser Fan Control 28 Condenser Fan Staging The first condenser fan stage will be started in conjunction with the first compressor to provide initial head pressure control The MicroTech controller continuously monitors the lift pressure referenced to several head pressure control setpoints and will adjust the number of operating condenser fans as required to maintain proper head pressure Head Pressure Control For each circuit the first stage of condenser fans will be wired in parallel with the compressor output so that they are energized with the compressor For chillers with optional SpeedTrol the first condenser fan stage will receive a control signal from the AOX board that in turn modulates the Johnson Controls S66DC 1 to provide variable speed fan operation Each circuit has 3 additional digital outputs available for refrigerant head pressure control Each output will energize an additional bank of condenser fans with each bank consisting of 1 or 2 fans depending on the size of the unit Each output energizes additional heat rejection due to increased airflow across the air cooled condenser regardless of the number of fans If the outdoor ambient temperature is grea
28. is true before beginning this procedure For communications to occur each networked controller must have the proper hex switch setting and the proper voltages at its port B terminals 1 Setthe network address hex switch setting to match the address on the engineering schedule Each controller must have a unique address 2 Turn on power to the level 2 controller Refer to the controller installation manuals for information on how to turn on power to each controller 3 Check the voltages of port B directly on the AMP connector The trunk must not be connected to the controller when you do this Use a DC voltmeter to test for proper voltages With the ground lead on the control panel chassis ground check the voltage at the and ground terminals Refer to Table 21 Port B voltages AMP type connector for the correct voltage levels If no voltage or improper voltage levels are found verify that the controller is energized 4 Check for proper communication trunk voltages at the field wiring terminals if any or directly on the connector The trunk must not be connected to the controller when you do this 47 48 If no voltage or improper voltages are found check the wiring between the port terminals and the field terminals if any using Table 20 Port B voltages AMP type connector and Table 21 Verify that the three conductors are properly terminated in the network communications connector If there is still a probl
29. low water temperature cutout high pressure cutout suction pressure cutout and freeze protection The operator can use the keypad to monitor various operating conditions setpoints or alarm messages gt Security password protection against unauthorized changing of setpoints and other control parameters gt Complete plain English diagnostics to inform the operator of system warnings and alarms alarms are time and date stamped so there is no guessing of when the alarm condition occurred In addition the operating conditions that existed at the instant of shutdown can be recalled to aid in isolating the cause of the problem Soft loading feature to reduce electrical consumption and peak demand charges during chilled water loop pulldown Easy integration into building automation systems via separate 4 20 milliamp signals for chilled water reset and demand limiting McQuay s Open Protocol feature is fully supported Flexible internal time clock for on off scheduling Communications capabilities for local system monitoring changing of setpoints trend logging remote reset alarm and event detection via IBM compatible PC The optional modem kit supports the same features from an off site PC running McQuay Monitor software Special service modes may be used to override automatic unit staging during system checkout and service 4 OM ALSMICRO Software Identification Controller software is factory installed and tested
30. there is no relay in the socket the output s MOV has failed and thus the Output Board must be replaced If the output load de energizes the relay that was pulled 15 defective Contact chatter Contact chatter is very rapid opening and closing of contacts It is usually caused by low voltage at the electromechanical relay or contactor coil If contact chatter is occurring on a relay or contactor connected to one of the Output Board solid state relays it is also possible that a faulty connection exists on the power supply terminals of the Aux Out plug connector on the MCB and the Output Board In very rare instances contact chatter can be caused by a faulty solid state relay Perform the following procedure to isolate the problem 1 Verify that the voltage at the load s power supply and at the solid state relay contacts is adequate 2 Remove power from the controller by opening Swap the suspect relay with a known good relay Try to choose a relay that will not affect unit operation Restore power by closing If the chatter does not stop go to step 3 If the chatter stops the suspect relay is defective Replace the relay 3 Remove power from the controller by opening Try to improve the connections in the AUX Out plug insulation displacement terminals by pressing down on the wires with a small screwdriver 4 Check all other wiring and connectors for bent pins or miswires If the chatter does not stop the electrome
31. 0 ohms If the component resistances are proper check the resistance of the field supplied loads if any and check the wiring and connections throughout the 5 VDC power supply circuit Disconnect the connector plugs from the modem and the power plug from all AOX 4 boards as applicable With circuit breaker open measure the resistance between field terminals DC GAD and 13 VDC It should be infinite If the resistance is infinite go to step 12 If the resistance is not infinite a short exists somewhere in the 13 VDC power supply wiring Reconnect the Aux Out connector plug to the MCB If there s a modem reconnect its AMP plug to port A With circuit breaker open measure the resistance between field terminals DC GAD and 13 VDC It should steadily rise to a value greater than 5000 ohms within approximately 30 seconds If the resistance rises above 5000 ohms go to step 13 If the resistance does not rise above 5000 ohms the MCB is defective One at a time reconnect the modem and each AOX 4 board as applicable Each time a component is reconnected measure the resistance between field terminals DC GAD and 13 VDC It should steadily rise to a value greater than 5000 ohms If the resistance rises above 5000 ohms repeat this step until the modem and all AOX 4 boards as applicable have been checked out If the problem persists it is indeterminate Obtain factory service 39 40 If the resistance does
32. 15 VAC power for the control transformer is derived from the 3 phase power connection provided by the electrical contractor A separate disconnect for the cooler heating tape and control circuit transformer may be supplied as options on some installations Wiring for these circuits is to be provided by the installing contractor and should conform to the National Electrical Code and all applicable local building codes Power supplies There are several internal power supplies used by the controller and its associated circuitry The regulated 5 VDC power on terminal 42 is used to support the analog inputs on the ADI Board and OM ALSMICRO ALSMICRO should not be used to operate any external devices unregulated 12 VDC power supply is available on field wiring terminal 56 and an unregulated 24 supply is provided at terminal 81 Both of these may be used for powering external devices such as low current relays and lights Demand limit and chilled water reset signals Separate 4 20 milliamp signals for remote chilled water reset and demand limit can be provided by the customer and should be connected to the appropriate terminals on the field wiring strip inside the control cabinet The optional demand limit and chilled water reset signals are 4 to 20 milliamp DC signals The resistive load used to condition the milliamp input signals is a 249 ohm resistor factory mounted on the ADI Board Communication ports Communication port
33. 39 63 4253 2808 64 4146 277 65 4042 274 6 394 274 66 3 4 2651 69 3655 2620 ALSMICRO 9 842 266 825 809 257 792 252 777 200 248 Pressure Transducers These transducers are selected for a specific operating range and provide an output signal which is proportional to the sensed pressure The typical range for evaporator sensors is 0 to 150 psig with a resolution of 0 1 psi Condenser pressure sensors have a range of 0 to 450 psi and a resolution of 0 5 psi The pressure transducers require an external 5 VDC power supply to operate that is provided by the MicroTech controller This connection should not be used to power any additional devices Figure 9 Pressure Transducer Red Dot Condenser Blue Dot Evaporator Liquid Presence Sensor A liquid level sensor mounted at the liquid injection port in the compressor casting determines the presence of liquid refrigerant Whenever the glass prism sensor tip is in contact with liquid the sensor output signal will be high 27 VDC If no liquid is detected the output will be low O VDC Figure 10 Liquid Presence Sensor 41 8 po OM ALSMICRO Sensor Data Sensor Locations Analog Inputs Analog inputs are used to read the various temperature and pressure sensors installed on the chiller as well as any customer supplied 4 20mA reset signals The controller s internal
34. 60 2EvpAdj psi 1CndAdj psi 2CndAdj psi Closed open blink N O blink N C 2 lt L 1 Table 44 Four Compressor Menu Alarms Menu mem Display Dead 1 Curr Alarm a EM 8 9 ___ o 221 DNE O Oo 0 0 0 O 8 HiPresStageDwn FreezeStageDwn LossofChWFlow Can tPumpDown NoStart LoEvap FailedPrePurge FaillowAmbient reezeStaProt HighLigPressDrop Motor Protect Repowera loss Below Minit INoLiquid Start Hi Dschrg Temp O Hi Cond Press Mech Hi Press BadSuctTempSen j BadEvapPresSen BadCondPresSen BadPhase Volts LvgWaterFreeze 5 5 O BadLvgWaterSen 74 LowSubCoolTemp pi 11100 mm dd yy Mg ALSMICRO Table Continued Next Page OM ALSMICRO 75 Table 44 Four Compressor Menu Alarms Continued Menu Hem Display Detam Range SSCS 11122000 oe T shot 1 0 00000 COC Opeps RR 90009 hp mt OoOo MN pnt 220 Sor J 31 HAF 1 _ Same asi Curabove S 1 WaCurAam a 1 WiPevAams 21222 2
35. AOL CIRCUIT BREAKER POWER CIRCUIT BREAKER MICROTECH CIRCUIT BREAKER FAX ALARM CHILLED WATER INTERLOCK COMPRESSORS COMPRESSOR SOLENOID CURRENT TRANSFORMER DISCONNECT SWITCH MAIN ELECTROMC EXPANSION VALVE FUSE CONTAOL CIRCUIT FUSE COOLER HEATER FUSEBLOCK CONTROL POWER FUSEBLOCKS FAN MOTORS GUARDISTOR RELAY GROUND FAIAT PROTECTOR GROUND COMPRESSOR HEATER HEATER EVAPORATOR JUMPERS LEAD JUNCTION BOX EVAP HEATER KEYPAD SWITCH amp DISPLAY PRESENCE SENSOR CONTACTORS COMPRESSOR DACK OR SIDE CTRL BOX BOX POWER PANEL CTRL BOX CTRL PANES CTRL BOK POWER PANEL INSIDE SPEEDTROL BOX CTRL BOX POWER PANEL CTRL BOX CTRL PANEL CTRL BOX CTR PANEL FIELD INSTALLED ON RAIL CTRL BOX CTRA PANEL CTRL BOX SWITCH PANEL CTRL BOK SWITCH PANEL CTRL BOX POWER PANEL CTRL BOX POWER PANEL CTAL BOX CTRL PANEL CTRL BOX POWER PANEL BOX CTRL PANEL CONTROL BOX CTRL PANEL CTRL BOX CTRL PANEL CTAL BOX CTRL PANEL CTRL BOX CTRL PANEL CONTROL BOX CTRL PANEL CONDENSER SECTION CTRL BOX PANEL CTRL CTRL PANEL CTRL BOX POWER PANEL BOX CTRL PANEL CTRL BOX POWER PANEL CTRL BOX SWTCH PANEL CTRL BOX POWER RESISTOR CURRENT TRANSFORMER SWITCH MANUAL START STOP SPEED CONTROL SIGNAL CONVERTER SOLENOID VALVE UQ UNES SOLENOID VALVE UQ INJECTION SOLENOID VALVE HG BYPASS TRANSFORMER MAIN CONTROL TRANSFORMER 120 249 CONTROL TRANSFORMER
36. Common to all Unit Refrigerant Circuits Pe Display Down Setpoints 1 Auto Hardware Voltage Incoming power phasing incorrect or not within voltage limits Volts Range Setting To prevent operation with reverse rotation or improper or unbalanced voltage LossofChW Auto No Setpoints Chiller Flow Switch open for more than 3 sec In Cooling Status Auto Upon flow switch closure To Prevent chiller freeze up due to loss of water flow to chiller LvgWater Manual Yes Monitor and keypad Chiller leaving water falls below the adjustable Freeze Water Trip Freeze setpoint 36F default Logic will not allow this alarm to occur in Auto Control LWT setpoint will default to 4 degrees F above the Water Freeze Trip setpoint To prevent chiller freeze up BadLvgWtr Manual None Controller detects an open or shorted leaving water sensor Sen To prevent unit damage due to operation with defective sensor 5 5VDC Manual None Voltage at Controller Analog Input not between 4 15 amp 4 94 VDC AI 5 To prevent operation with improper voltage to transducers and controller Circuit Alarms NoStart Manual Memory location Evaporator pressure below 4 psi when compressor start is LoEvap requested Circuit will not start To prevent start up with no refrigerant in the unit NoEvapPres Manual Memory locations Evaporator pressure fails to drop a preset amount during start up 6 Drop psig in 16 seconds To shu
37. EGORY group CONTROL key one time This switches the display to Menu 13 Two Screw Compressor Control mode the first menu in the CONTROL category 2 Press the MENU group NEXT key once This shifts the display to Menu 14 Two Screw Compressor Lvg evap spts values for R 22 refrigerant Leaving Evaporator Setpoint 3 Press the ACTION group DEC key one time This prompts the user to enter the password Enter Enter Enter Enter 4 After the Password Verified message press the ACTION group DEC key four times This changes the menu item entry to 42 F 5 Press the ACTION group ENTER key one time This stores the new entry into the MicroTech controller memory 6 Pressing the CATEGORY group STATUS key then shifts the display back to Menu 1 Chiller status OM ALSMICRO Personal Computer Specification OM ALSMICRO For McQuay Monitor Software 1 IBM PC or 100 true compatible 486DX or better including a 3 Yanch 1 44 MB floppy diskette drive utilized for loading the MicroTech Monitor program into the hard disk of the computer Also provides capability of archiving historical data and system back up b 8 Megabyte RAM Random Access Memory The computer must have 8 Megabytes in order to run the MicroTech Monitor Program c RS232 serial port A direct communications interface connection between the PC and the MicroTech Controller The communications port must be recognized as COMI
38. Lift100 xxx 5 StageUpErr xxx_ 300 20090 6 8 80 5050 Demand Limits Demand Lim xstg __ j ManDemand xstg 8 48 Table 25 Two Compressor Menu Time Date mem Dem ______ Time Date Ri 099 55 56 Table 26 Two Compressor Menu Schedule Display 1 OverridesxxxxHr 0 0 63 5 NMP Schedule xx 182 xc 059 OE Sum e 32 nm a 1 NEN Holiday Date ER Date N A 1 xx 0 2 1 Dur xxDay s Table 27 Two Compressor Menu Service Test Menu Display Dean Range Service Test 1 0 0 0 06 2 1 Outputi Off OT 3 H2EXVPos Hi xxx 0 90760 4 0 0760 5 M4Oupt4 Oft 0006 6 85 5 o 7 6Output6 of 8 7Output7 of 0006 9 j f8Oupu8 Of 10 foOuput9 Off OT 11 0 12 1106 ____ 13 12 1208 000 14 1 13506 000 15 140utput14 0ff __ 1 0006 O 16 15 15506 OnoOf 17 fi6Ouputic Oft
39. Optional Hot Gas Bypass SV6 Not Used Compressor 4 Contactor Compressor 4 Top Solenoid Valve feed Compressor 4 Bottom Right Solenoid Valve feed Compressor 84 Bottom Left Solenoid Valve vent Condenser Fan Contactor M 42 Condenser Fan Contactor M 43 Condenser Fan Contactor M 44 Condenser Fan Contactor M 45 N 4 N OM ALSMICRO 17 Installation 18 Controller Calibration The control software is installed and tested by the factory prior to shipping therefore no periodic calibration of the controller is required All control and safety setpoints will be checked and adjusted if necessary by the McQuayService start up technician prior to starting the unit The MicroTech controller contains default setpoints that will be appropriate for most common installations Field Wiring Analog sensors and transducers All sensors and transducers required for normal chiller operation are installed and wired by the factory Any optional analog signals provided by the installing contractor require twisted shielded pair wire Belden 8760 or equal Digital input signals Remote contacts for all digital inputs such as the chilled water flow switch and the remote start stop switch must be dry contacts suitable for the 24 VAC control signals produced by the screw chiller panel Digital outputs Devices wired to the digital outputs typically are an optional Chilled Water Pump control relay or an Alarm Annunciator The MicroT
40. S SUPPLY CONTROL CIRCUIT TRANSFORMER OPTION OSCONNECT BY OTHERS 10 20VAC FUSE CONTROL gt T BY OTHERS IF SEPARATE EVAPORATOR MEATER POWER OPTION IS USED REMOVE WIRES 540 AND 545 SEPARATE EVAPORATOR DISCONNECT HEATER POWER OTHERS 8 3 OPTION 120v AC BY OTHERS N 24V OR 120 SOLID STATE RELAY 24V OR 20 15 AMPS CHW PUMP RELAY BY OTHERS TB4 4 20 MA FOR BY OTHERS IMPEDANCE NMHERENT IN GND MICROTECH CONTROLLER DEMAND LIMIT 2500 LOAD BY OTHERS IMPEDANCE 1 CLR CONNECTION TO RS232 E FOR MODEM OR 3 BLK R3232 RC COMMUNCATION DIRECT CONNECTION PORT 1 5 GND GND CONNECTION 3 BLK 85485 REMOTE MONITORING SEQUENCE 5 4 CLR 185485 INETWORK MASTER PANEL g CE 5 GND GND CLOCK AUT REMOTE STOP p 4b 5 REMDTE mne CONTROL MJ USED REMO SITUE E FROM TERM 60 TO 61 MANUAL CHW FLOW SWITCH m ACER a PHI MM OTHERS ALARM BELL FACTORY SUPPLIED 5 OPTION ALARM FELO WIRED ALARM BELL DUTPUT RELAY 0 24 Vac 35 MAX 89 90 Wiring Legend ALARM BELL RESISTOR CURRENT TRANSFORMER ANALOG DIGITAL INPUT BOARD SURGE CAPACITOR COMPRESSOR CAPACITOR SPEEDT
41. al Hardware overload Motor Protection opened due to high amps or high motor temp y Gardistor reset overload To protect compressor motor from excessive amps or high motor temp operation Can tPump Auto Press setpoint Circuit failed to reach Stop pumpdown Setpoint default of 34psig in Down Mon Key 90Sec during any pumpdown shutdown 120Sec timer To alert Service Tech That circuit may not be pumping properly Memory Address Below Min Manual Memory addresses When Condenser pressure Evaporator pressure lt Setpoint for Lift 254 seconds this alarm occurs Setpoint at 25 and 50 load is 30psig for R22 and 134A 24psig for 407C Setpoint at 75 and 100 load is 50psig for R22 and 134A To shutdown the circuit if compressor power is lost during operation PreCursor alarm for low press differential conditions Evaporator Pressure Transducer is failed open or shorted OM ALSMICRO 33 34 prevent operation with bad pressure transducer OM ALSMICRO Alarm Pump Adjustable Alarm Description and Reason for Alarm Display Down Setpoints 23 BadCondPres Manual No None Cond Pressure Transducer is failed open or shorted Sen To prevent operation with bad condenser press transducer 24 BadSuctTemp Manual No None Suct Temperature Sensor is failed open or shorted Sen To prevent operation with bad suction line temp sensor used for Exp Valve control 25 LowSubCool Manual Yes 5F is adjustable
42. arameter can be made or before an alarm can be cleared the display prompts the user with an Enter Password message At this prompt the password must be entered before the user can continue with the action Enter Enter Enter Enter A INCR When changing the value of a menu item entry pressing INCR increments the displayed value to the next higher value or selects the next available option B DECR When changing the value of a menu item entry pressing DECR decrements the displayed number to the next lower value or selects the previous available option C ENTER Once a change has been made to a desired value pressing ENTER locks in the new value and causes it to take effect D CLEAR Pressing ALARMS followed by CLEAR clears the current alarm Also when a change is made to a menu item pressing CLEAR returns the display to the original value as long as ENTER has not yet been pressed Note The cause of an alarm should always be determined and corrected before clearing the alarm through the keypad Example of keypad operation As an example of using the keypad key functions consider reprogramming the Leaving Evaporator Setpoint from 44 F to 42 F This consists of changing the Menu 14 Two Screw Compressor Lvg evap spts values for R 22 refrigerant entry from 44 F to 42 F Assume Menu 1 Chiller status is currently in the display The following key sequence is followed 1 Press the CAT
43. assword When changing any menu item entry the user is prompted to enter the password The change will not be allowed until the correct password is entered The password for ALS units is always the successive pressing of the following ACTION group keys ENTER ENTER ENTER ENTER Once this has been done the user can make changes to menu item entries After entering the correct password the controller will allow a 5 minute time period during which the operator may make any necessary setpoint adjustments Any keypad activity will reset the timer for the full 5 minutes so the password only needs to be entered once per session After 5 minutes of inactivity the password access time will expire providing protection against unauthorized users Category group The keys in this group provide quick access to strategic menus throughout the menu tree structure This reduces the need to step through all the menus one by one in order to reach the desired menu A STATUS Pressing the STATUS key at any time shifts the display to the first menu of the STATUS category which is Menu 1 CHILLER STATUS B CONTROL Pressing the CONTROL key at any time shifts the display the first menu of the CONTROL category which is MENU 13 or 16 or 19 CONTROL MODE 2 3 4 compressor C ALARMS Pressing the ALARMS key at any time shifts the display to the first menu of the ALARMS category which is MENU 28 31 34 1 CURRENT ALARM 2 3 4 compre
44. be hot This is because the relay output and the voltmeter form a continuous circuit in which the relay s resistance though high is insignificant compared to the voltmeter s resistance This means that nearly all the voltage is dropped across the voltmeter Therefore the voltmeter indicates that voltage is present If a low wattage light bulb of the appropriate voltage is used instead of a voltmeter the bulb s low resistance will load the circuit enough to eliminate the false voltage indication In this situation an incandescent test lamp is a better tool than a voltmeter Figure 19 Testing A Typical Relay Circuit Figure 20 Testing A Typical Relay Circuit With A Disconnection 115 Output board Output board 00 13 Neutral Neutral MCB Replacement If an MCB board is defective and must be replaced the proper controller software must be loaded into the replacement MCB This can be done either at the factory or at the building site if a PC equipped with appropriate Monitor software is available The factory will download the proper controller software into a replacement MCB board before it is shipped if you include the program code with the replacement MCB part order Only McQuayService or authorized service agencies are allowed to do this Connecting the Communications Trunk Use the following three procedures to connect the chiller controllers to the network Communications cable check The network communicati
45. blem persists it is likely that the MCB is defective Troubleshooting Analog Inputs An analog input such as a temperature sensor is connected to the Analog Input terminal strip on the ADI board The ADI board then conditions the analog input The conditioned input is transferred to the MCB via a ribbon cable Analog input not read by the MCB If the MCB appears to be functioning properly and the analog input is not being read by the MCB perform the following procedure 1 Try cycling power to the controller by opening and then closing circuit breaker 2 Check the ribbon cable power wiring connector and the field wiring connections from the analog input device Look for bent pins cable on backwards or miswires Restore power after reconnecting all cables and wires 3 Ifthe problem persists try swapping a known good ribbon cable an ADI board or analog input device Swap these components separately to isolate the problem Remove power from the controller before disconnecting the suspect component and restore power after connecting the replacement component If the problem persists it is likely that the MCB is defective Troubleshooting Digital Inputs A digital input device is connected to the Digital Input terminal strip on the Input Conditioning Module Terminal Board 24 VAC supplied by the CSC is sent to the digital input device via a supply wire CSC is a Chiller System Controller that is a separate MicroTech Network
46. chanical relay or contactor is probably defective Troubleshooting Solid State Relays As shown on the unit wiring diagrams the solid state relays on the Output Boards all have normally open contacts Actually these contacts do not exist as they do in electromechanical relays Instead of using contacts to switch the load the solid state relay changes its resistance from low closed when it is energized to high open when it is de energized This high resistance is approximately 1 OOK ohms Because the output circuit through the solid state relay remains continuous regardless of whether the relay is energized troubleshooting a solid state relay with a voltmeter can be tricky OM ALSMICRO ALSMICRO In a typical circuit a power source is connected across a single relay output a load see Figure 19 In this circuit a solid state relay will behave like an electromechanical relay If the relay is energized the relay output will be hot If the relay is deenergized a small voltage will be present The circuit shown in Figure 20 is similar to a typical circuit the difference is that there is an open set of contacts or a disconnection between the relay output and the load In this circuit a solid state relay will not behave like an electromechanical relay If the solid state relay is energized the relay output will be hot as expected However if the solid state relay is de energized the relay output will still appear to
47. charge temperature is above 160F System Alarms Alarm conditions that are common to both refrigerant circuits are considered to be system alarms On a system alarm the MicroTech controller will shut down both compressors and energize the alarm output Freeze protect stage down and freeze stat protect The controller records the amount of time the evaporator refrigerant pressure is below the freeze stat setpoint default 54 psi The magnitude of the error will determine the time delay before a circuit stage down or alarm shutdown occurs Table 19 Error SDDeay AlarmDelay Once the time delay is satisfied the controller will stage down once every 20 seconds If the controller stages down to cooling stage 0 the circuit will pump down and the compressor will stop The circuit will restart automatically when the anti cycle timer expires OM ALSMICRO 35 MicroTech Controller Test Procedures 36 CAUTION Service test mode should only be used by McQuayService personnel or other factory trained technicians The following test procedures will disable all normal chiller controls and safeties All compressors MUST be disabled by opening circuit breakers or by disconnecting the 3 phase power before beginning tests Failure to do so can result in severe compressor damage Service Test Digital Outputs Select control mode Menu 13 Two Screw Compressor Control mode and set the chiller s control mode to Service Testing
48. e 1 equals on and 0 equals off By manipulating field wired devices flow switch remote stop switch etc and watching the keypad display the status of the second eight digital inputs can be verified Exit the Service Testing mode by selecting the desired chiller operating mode from Menu 13 Two Screw Compressor Control mode OM ALSMICRO Keypad Display Overview The information stored in the MicroTech controller can be accessed through the keypad using a tree like structure This tree structure is divided into Categories Menus and Menu items There are three categories that make up the tree structure STATUS CONTROL and ALARM Each category is divided into Menus and each menu into Menu Items The three categories are described below Status Category Menus and menu items in this category provide information on the MicroTech operating conditions and the chiller operating conditions The entries under each menu item in this category provide information only and are not changeable through the MicroTech keypad Control Category Menus and menu items in this category provide for the input of all the unit parameters These include cooling control compressor control and condenser fan control parameters as well as time schedules and alarm limits The entries under these menu items are changeable through the MicroTech keypad Alarm Category Menus and menu items in this category provide information regarding current and previous a
49. e Comm Off Remote Sw Off Time Clock e Off AmbientLck jo Starting C O Hodsage xmin 1 Status Off SystemSw uq C y Off ManualMde Off Alarm Off CycleTime xx p Off PumpDwnSw WaitFlooded Ready j Stating 7 Pre Purge Opened owAmbStat Cooing Cap 1 Pumping Down 00 O Circ 2 Status See Circ 1 Above Water Temp s Short F Short F Short F Short o 79 Circ 2 Pres s SeeCirc Above SuctLine xxx VAS 5 Super Ht xxx x F C N A xx F C 145 F Open F Short F C 145 Open F Short F C OM ALSMICRO 53 54 Satur C F ______________ Open Short 6 LiquidLn xxx xF C Short F C SubCoolg xxx xF C N A xx F C Table 22 Continued Menu Display Range Circ 2 Temp s Circ 1 Above Chiller Amps 1 PerentRLA 1 Ht Total axxxxxx 2 j f2Toal oox 1 25 4 4 4 050 1 75 p uS 6 1 100 axxxxxx 2 25 8 205096 axxxx
50. ear in the display for the particular item The entry that shows in the display depends on the operating status of the unit 2 Control Category Where more than one menu item entry is listed under a menu item the list includes all the choices from which the user can select The selected entry appears in the display 3 Alarm Category The entries listed include all the possible alarm messages The display reads the alarm conditions that occur Status menus Provide chiller operating information and display of sensor readings The items listed under these status menus are affected by the settings under the associated control menus and are not directly adjusted via the keypad Control menus All adjustable control parameters and setpoints time schedules control options and alarm thresholds are accessed through these menus CAUTION Any changes to these parameters must be determined and implemented by qualified personnel with a thorough understanding of how these parameters affect the operation of the unit Negligent or improper adjustment of these controls may result in damage to the unit or personal injury Alarm menus Display any alarm conditions that may be present in the unit All alarm messages are accompanied by the date and time when the alarm occurred OM ALSMICRO Menus for Two 2 Screw Compressor Units Table 22 Two Compressor Menu Status Dmm wm mem 0000 mee Chiller Status ees Status Off Remot
51. ech output device is a normally open solid state relay with an on board replaceable 5 amp fuse The model 250 controller activates a solid state relay by sending a trigger signal to the output board via the attached ribbon cable The relay responds to the trigger by lowering its resistance that allows current to flow through its contacts When the controller removes the trigger signal the relay s resistance becomes very high causing the current flow to stop The status of all outputs is shown by individual red LEDs for ease of determining output status Interlock wiring The installing contractor provides all interlock wiring to field devices such as flow switches and pump starters Refer to the Field Wiring Drawing as well as the unit wiring schematics and typical application drawings at the end of this manual for details External alarm circuit The MicroTech panel can activate an external alarm circuit when an alarm or pre alarm condition is detected 24 VAC voltage source is available at field wiring terminals 102 through 107 to power an external alarm device such as a bell light or relay An alarm annunciator rated for a maximum load of 1 8 Amps at 24 VAC is to be provided and wired by the installing contractor The normal and alarm states for the 24 VAC alarm signal are programmable by the operator Available settings are gt Pre alarmannunciation Close or Open or Blink Alarm annunciation Close or Open Power wiring 1
52. eeze Stat Dwn setpoint for a period of time to calculate an error see DD pg 55 Algorithm Timer 113 13 x press diff Press diff 2 Freezestat setpoint Evap press Timer determines when the stage down will occur To prevent evaporator tube freeze due to low pressure operation 14 Freezstat Manual Keypad and Monitor Evaporator pressure falls and stays below Frz Stat setpoint for a Prot timer longer than freezestagedown The first freezestat protect is auto clearing The second is a manual reset if it occurs within 60 minutes of the first occurrence Awaiting new To prevent evaporator tube freeze due to low pressure operation logic 15 Cond Pres Manual Trip adjustable on Condenser pressure exceeds set max value 380default To prevent excessive condenser pressure operation 16 HiPresStag Auto Trip adjustable on When cond pressure falls within 20psig of the HP trip setpoint Dwn default of 380psig the compressor will stage down 30 min must pass from time of stage down and the OAT must fall 3F below temperature of stage down before a stage up occurs 17 HiPresStage Trip adjustable on When condenser pressure falls within 40psig of HP trip setpoint The compressor will not stage up 18 Hi Mech Pres Manual Hardware switch Condenser pressure exceeds Mech Hi Press switch value 380psig To prevent excessive condenser pressure per Safety agency requirements Motor Protect Manu
53. em verify that the level 1 controller is energized and that the communications trunk wiring is intact 5 Plugthe network connector into port B 6 Verify communications have begun between the level 1 controller and the level 2 controller To verify communications using Monitor for Windows software network diagnostics must be performed To run network diagnostics select the pull down menu Comm Select Network Diagnostic which will then display the Network Diagnostics Parameters Setup dialog box Using the Network Diagnostics Parameters Setup dialog box you can choose to continually loop the diagnostics or have a single sweep of each controller being connected to the network You can also perform the following functions Display Program ID and status Restrict display of level 3s to units with errors gt Clear communications errors if found gt Log errors to file As the different controllers are connected to the network their information is displayed on the Network Diagnostic Error Display screen By looking at the headings labeled Address and Error codes network communications to a particular controller can be verified If there are no error codes network communications to the controller was successful If the Error code reads Does not respond a communications problem has occurred For more on network diagnostics see Chapter 5 Comm Menu in MicroTech Monitor for Windows user s manual If a communications
54. ent start timer Low Ambient timer 360 Pressure Difference X 15 If the calculated low ambient timer value is greater than 360 the compressor will be stopped the alarm output will be activated and the display will indicate FailLowAmbsStart Cool Stage Circuit capacity at initial start will be 5096 Once the chiller has started the MicroTech controller will add or subtract cooling capacity to maintain the chilled water setpoint The current cooling stage will be displayed on the keypad display Automatic chiller staging may be overridden by selecting Manual Cooling as the operating mode and then choosing the desired cooling stage CAUTION Manual Cooling will by pass all interstage timers This will result in rapid compressor stage up and possible chilled water temperature overshoot The unit will not unload as the chillers water temperature reaches the setpoint Compressor Control OM ALSMICRO Normal Compressor Staging Logic The Compressor Staging Logic uses an adjustable control band and interstage timers to determine the correct number of cooling stages to activate project ahead temperature calculation provides stable operation The total number of cooling stages for each circuit is dependent upon the number of cooling stages setpoint Operation at 25 is not allowed compressors 3 and 4 For compressors 1 and 2 25 is selectable by setting MinStage 1 Then 30 minutes is the maximum timer sett
55. ent to the analog output device The analog output signals are 41 42 sent from the 4 by connecting a two pin Phoenix connector to the Analog Output Ports on the 4 Analog output device is operating correctly If the MCB appears to be functioning properly and the analog output device is not operating correctly perform the following procedure 1 Trycycling power to the controller by opening and then closing circuit breaker 2 Check the ribbon cable s power wiring from the transformer to the 4 field wiring connections from the 4 to the analog output device and the power wiring from the external power supply to the output device Look for bent pins cable on backwards or miswiring Restore power after reconnecting all cables and wires Note If the analog output signal supplied by the MCB is a voltage signal 0 5 0 10 VDC the external power supply ground must be grounded to the MCB chassis ground 3 If the problem persists try swapping a known good 4 ribbon cable s analog output device or external power supply Swap these components separately to isolate the problem Remove power from the controller and analog output device before disconnecting the suspect component and restore power after connecting the replacement component If the problem persists it is likely that the MCB is defective Troubleshooting Output Boards Each output on the Output Board consists of a solid sta
56. gh Pressure Switch Circuit Alam Liquid Normal High Liquid Pressure Drop 1 Alarm of ___ Normal 7 Pumpdown Mechanical High Pressure Switch Gircuit 2 Noma Liquid Motor Protect Compressor 2 Normal Alarm A Alarm Off Alarm o Alarm A Alarm Alarm A Alarm Alarm o Alarm A Alarm Normal No N No High Liquid Pressure Drop 2 0 0 Start Flow Pumpdown Mechanical High Pressure Switch Circuit Alam 17 Liquid Normal High Liquid Pressure 43 Alarm ___ NetUused 0 n Phase Volt Monitor Multi Poit Normal e a Pumpdown Mechanical High Pressure Switch Circuit 4 Alam Liquid Normal High Liquid Pressure 4 Alarm Normal Noted 2 Used Used 7 Pumpdown Switch Compressor 4 Pumpdown Optional Analog Outputs Table 9 Analog Outputs Signal Range SpeedTrol Circuit 1 0 10 VDC SpeedTrol Circuit 3 0 10 VDC SpeedTrol Circuit 4 0 10 VDC l p p 4 SpeedTrol Circuit 2 0 10 VDC 15 16 Digital Outputs Table 10 Digital Outputs 2 Compressor Unit r on 0 AlmLEDandConact Programmable 10 ChnitedWaerPump Rm 2 EXV Seia Datat 3 EXV Serial Data 4
57. he above Off conditions are true the MicroTech controller will initiate a start sequence and energize the chilled water pump output relay The display will indicate Starting as the operating mode The chiller will remain in the Waiting For Flow mode until the field installed flow switch indicates the presence of chilled water flow If flow is not proven within 30 seconds the alarm output will be activated and the chiller will continue to wait for proof of chilled water flow When chilled water flow is re established the alarm will be automatically cleared Waiting for Load Once flow is established the controller will sample the chilled water temperature and compare it against the Leaving Chilled Water Setpoint the Control Band and the Load Delay which have been programmed into the controllers memory the leaving chilled water temperature is above the Leaving Chilled Water Setpoint plus Whe adjustable Control Band plus the Start up Delta Temperature Setpoint the controller will start the lead compressor Start Requested In the Start Requested Mode the electronic expansion valve is fully closed The MicroTech controller will read the evaporator pressure to ensure that at least 4 psi of refrigerant pressure is present If the evaporator pressure is less than 4 psi the compressor will not be enabled and the display will read NoStart LoEvap Prepurge In order to purge the compressor of any liquid refrigerant that may be present the starti
58. igital output ribbon cable to the MCB Cycle power to the controller and check the power fuses If both fuses are intact go to step 9 If either fuse blows check Output Board and the connecting ribbon cable Either of these may be defective If there are any AOX 4 boards reconnect the expansion bus ribbon cable to the MCB otherwise go to stop 10 Cycle power to the controller and check the power fuses If both fuses are intact go to step 10 If either fuse blows check the analog output expansion modules if any the connecting ribbon cables and the field wiring for shorts Any of these may be defective With circuit breaker open measure the resistance between field terminals DC GAD and 5 VDC It should be greater than 20 ohms If the resistance is greater than 20 ohms go to step 11 if the controller is equipped with at least one 4 board or a modem Otherwise the problem is indeterminate Obtain factory service If the resistance is less than 20 ohms it is likely that the keypad display the Output Board or an external field supplied load is excessively loading the MCB s 5 VDC power supply Isolate the problem by taking resistance measurements on each of these devices with the wiring disconnected The resistance across the power input terminals on the keypad display G and 5V should be close to infinite The resistance across the power input terminals on the Output Board and should not be less than 300
59. in each panel prior to shipment The software is identified by a program code that is printed on a small label attached to the controller The software version may also be displayed on the keypad display by viewing the last menu item in the Misc Setup menu The software version is the 6th amp 7th location of the software number In the example the version 18 19 and the revision to the software 15 Revisions are released in alphabetical order Hardware 3 2 19 Software Screw Chiller Fi Revision Number of Compressors Version Refrigerant lt 2 R22 S SI Type 3 R134a Controller Layout All major MicroTech components are mounted inside the control section side of the unit s control cabinet The individual components are interconnected by ribbon cables shielded multi conductor cables or discrete wiring Transformers T 2 and T 4 provide power for the system Allfield wiring must enter the control cabinet through the knockouts provided and be terminated on field wiring terminal strips The standard ALS keypad display is located inside the control cabinet for protection from the weather See Figure 1 for typical control cabinet layout Figure 1 Typical control cabinet layout Low ALSMICRO 5 Component Data Microprocessor Control Board MCB1 The Model 250 or 280 Microprocessor Control Board contains the electronic hardware and software required to moni
60. ing allowed at 25 If the evaporator Delta T is less than 1 degree F then 5 minutes at 25 load is allowed Operation at 25 load is not allowed if the outside ambient air temperature is below the minimum setpoint of 60 F 21 Compressor Staging Control Sequence Four Compressor Unit Staging Up Staging Down Lead Lag 1 Lag 2 Lag 3 Unit Lead Lag 1 Lag2 Lag3 Unit Comp Comp Comp Comp Capacity Comp Comp Comp Comp Capacity 23 S 0 0 0 0 7 50 50 75 5 50 7 50 10 50 11 75 12 75 75 75 75 75 75 75 14 75 75 15 100 16 100 100 0 13 75 Three Compressors Unit Staging Up Comp Comp Capacity Comp Comp Comp Capacity 00 25 0 0 83 0 0 0 0 0 50 50 75 75 75 Lead Comp 50 75 50 75 75 75 75 75 100 100 100 0 0 50 5 50 5 75 75 100 100 N 9 gt 666 75 75 666 75 75 75 100 10 11 12 Two Compressors Unit Staging Up Lead Lag 1 Unit Lead Lag 1 Unit Comp Comp Comp Comp Capacity y 0 xe 0 3 37 5 50 0 62 5 5 aa 25 0 75 75 750 22 ALSMICRO ALSMICRO 87 5 8 100 0 Project Ahead Calculation The Project Ahead Calculation provides protection against an overshoot condition when the chilled water temperature is outside the control band
61. lable on all McQuay ALS products contains a Model 250 or 280 Microprocessor based controller which provides all monitoring and control functions required for the safe efficient operation of the unit The operator can monitor all operating conditions by using the panel s built in 2 line by 16 character display and keypad or by using an IBM compatible computer running McQuay Monitor software In addition to providing all normal operating controls the MicroTech controller monitors all safety devices on the unit and will shut the system down and close a set of alarm contacts if an alarm condition develops Important operating conditions at the time an alarm occurs are retained in the controller s memory to aid in troubleshooting and fault analysis The system is protected by a password scheme which only allows access by authorized personnel The operator must enter a valid password into the panel keypad before any setpoints may be altered Table 1 Unit Identification Unit Identification ALS Air Cooled Chiller with Screw Compressors Control Panel Features gt Flexible control of leaving chilled water with convenient reset capability gt Enhanced head pressure control on air cooled units resulting in increased total unit SEER gt gt Convenient easy to read 2 line by 16 character display for plain English readout of operating temperatures and pressures operating modes or alarm messages Keypad adjustment of unit safeties such as
62. larm condition Display Format The current MENU is shown on the top line and the current MENU ITEM is shown on the bottom line of the display The operator cannot select either English Inch Pounds or metric SI units via the keypad The units must either be ordered English or Metric or alternatively have revised software downloaded into the unit in the field Inch Pound Units Temperature F Fahrenheit Pressure Psi Pounds per square inch Psig Pounds per square inch gauge Psid Pounds per square inch differential SI Units Temperature C Celsius Pressure kPa kilo Pascal kPag kilo Pascal gauge kPad kilo Pascal differential OM ALSMICRO 37 MicroTech Component Test Procedures 38 Status LED diagnostics The MCB status LED indications can aid in controller diagnostics If the status LEDs do not operate normally as described in the Component Date section of this handout see Table 1 and Table 2 there is a problem with the MCB Following are troubleshooting procedures for the various symptoms Red LED remains on If the red LED remains on after the 5 second self test period it is likely that the MCB is defective However this can also occur in some instances if there is a power supply problem Refer to Troubleshooting Power Problems below Red and green LEDs off If the red and green LEDs do not turn on after power is applied to the controller there is likely a defective component or a pr
63. munications It has been tested and found to comply with the limits for a class A digital device pursuant to part 15 of the FCC rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense McQuay International disclaims any liability resulting from any interference or for the correction thereof CAUTION The McQuay MicroTech control panel contains static sensitive components A static discharge while handling electronic circuit boards may cause damage to the components To prevent such damage during service involving board replacement McQuay recommends discharging any static electrical charge by touching the bare metal inside the panel before performing any service work CAUTION Excessive moisture in the control panel can cause hazardous working conditions and improper equipment operation When servicing equipment during rainy weather conditions the electrical devices and MicroTech components housed in the main control panel must be protected The MicroTech controller is designed to operate within an ambient temperature range of minus 40 to plus 185 F and a maximum relative humidity of 9596 non condensing General Description The MicroTech Unit Control Panel avai
64. ng compressor is operated at 5096 capacity while the electronic expansion valve is held fully closed The refrigerant circuit will continue to run in this mode until either the evaporator refrigerant pressure drops to less than 40 psi or 60 seconds has elapsed If the evaporator pressure does not drop to 40 psi within the 60 seconds the compressor will continue to run and the display will read Failed Prepurge The alarm is logged in the alarm buffer OM ALSMICRO With the evaporator pressure less than 40 and the compressor still running the electronic expansion valve will be driven open to 300 steps If the evaporator pressure rises above the freeze stat setpoint the chiller will advance to Cool Staging Mode If the circuit is in Cool Staging Mode and after 20 seconds the evaporator pressure remains below the freeze state setpoint but is greater than 2 psi the controller will transition to Low Ambient Start Mode Low Ambient Start If the difference between the freeze stat setpoint and the evaporator refrigerant pressure is greater than 12 psi the low ambient start timer will be set to 180 seconds The compressor will continue to run for 180 seconds from the moment the expansion valve is opened in an attempt to build up the evaporator pressure If the difference between the freeze stat setpoint and the evaporator refrigerant pressure is greater than 12 psi the following calculation will be used to set the low ambi
65. not lit The Keypad Display Interfaces supplied with the MicroTech control panel is equipped with a back light If the light does not come on check for 5 VDC at terminal 9 on the IDC connector on the KDI and for 5 VDC on the field wiring terminal strip Check for 5 VDC on the IDC connector on the MCB aux out To check for the 5 VDC on the IDC connector pull back the plug about one eighth of an inch and place the test leads against the exposed pins If there is no voltage the MCB is probably defective Display is blank or garbled If the MCB appears to be functioning properly and the display is completely blank or garbled perform the following procedure 1 Trycycling power to the controller by opening and then closing circuit breaker 2 Try adjusting the contrast trim pot which is located on the back of the keypad display assembly If the contrast trim pot has no effect it is likely that either the keypad display or its ribbon cable is defective OM ALSMICRO ALSMICRO 3 After removing power from the controller check the ribbon cable and connections between the keypad display and the MCB Look for bent pins Restore power after reconnecting the ribbon cable 4 Try swapping a known good ribbon cable and keypad display Swap these components separately to isolate the problem Remove power from the controller before disconnecting the suspect component and restore power after connecting the replacement component If the pro
66. o the Auto position for approximately 3 seconds and then back to the Stop position If the evaporator pressure is above the Begin Pumpdown Pressure setpoint the controller will initiate a pumpdown sequence and the compressor will stop when the evaporator pressure falls below the StopPumpdownPressure setpoint Service Pumpdown The normal pumpdown sequence will stop when the evaporator pressure equals the Stop Pumpdown setpoint pressure control setpoint called FullPumpDown has been provided which will allow extended pumpdown for service purposes The default value for the FullPumpDown setpoint is No By changing this setting to Yes the circuit will attempt to pump down to 10 psi during the next pumpdown cycle If 10 psi cannot be obtained the compressor will stop after 300 seconds have elapsed The setpoint will be set to No automatically at the end of the cycle Note All pumpdown modes are disabled if the system switch SI is in the Stop position Note Compressor capacity during a pumpdown sequence will be 5096 CAUTION Do not close any liquid line service valves for a service pumpdown The compressor must have liquid injection available whenever it is running Failure to provide liquid injection could cause compressor damage OM ALSMICRO 31 Safety Systems ALS Unit MicroTech Control Alarms Note Those alarms which are Automatically reset will log an occurrence in the alarm buffer Unit Alarms
67. oblem in the controller s power distribution circuits Refer to Troubleshooting Power Problems below Troubleshooting Power Problems The MCB status receives 18 VAC center tapped power from a transformer It then distributes both 5 VDC and 13 VDC power to various MicroTech components A problem that exists in any of these components can affect the MCB and thus the entire control system Power problems can be caused by an external short which can blow a fuse or a defective component which can either blow a fuse or create an excessive load on the power supply An excessive load can lower the power supply voltages to unacceptable levels Use the following procedure to isolate the problem Note This procedure may require two or three spare MCB fuses Verify that circuit breaker is closed 2 Remove the MCB Power In connector and check for 9 VAC between the terminals on the plug corresponding to terminals 2 and 3 on the board Figure 2 Then check for 9 between the terminals on the plug corresponding to terminals 1 and 3 on the board Readings of 9 12 VAC are acceptable If 9 VAC is present between both sets of terminals go to step 3 If 9 VAC is not present between both sets of terminals check both transformers and all wiring between the 115 VAC source and the Power In plug 3 Remove power from the controller by opening circuit breaker Check the MCB power supply input fuses Fl and F2 with an ohmmeter
68. oller Figure 5 EXV board 32 Analog Output Board Board With Optional SpeedTrol The AOX Board converts control instructions from the M250 s expansion bus into an analog control signal suitable for driving a variable speed condenser fan Each AOX Board is factory set via jumper to provide an output signal of 0 10 VDC Figure 6 AOX board The Keypad Display is the primary operator interface to the unit All operating conditions system alarms and setpoints can be monitored from this display and all adjustable setpoints can be modified from this keyboard if the operator has entered a valid operator password OM ALSMICRO 7 Figure 7 display Sensors Transducers Standard Sensors Evaporator Leaving Water Temperature Evaporator Refrigerant Pressure Circuit 1 2 3 amp 4 Condenser Refrigerant Pressure Circuit 1 2 3 amp 4 Suction Temperature Circuit 1 2 3 amp 4 Liquid Line Temperature Circuit 1 2 3 amp 4 Provides direct display of subcooling and superheat Entering Evaporator Water Temperature Outside Ambient Air Temperature Optional Sensor Packages Percent Unit Amps on 2 Compressor Units Percent total unit amperage including compressors and condenser fans Does not include externally powered equipment such as water pumps Percent Compressor Amps on 3 Compressor Units and Percent Circuit Amps 1 amp 3 2 amp 4 on 4 Compressor Units
69. on using a spreadsheet program It should be noted however that for maximum convenience and functionality the computer should be considered a dedicated computer for the MicroTech system The communications cable from the unit control panel to the personal computer is shielded twisted pair wire Belden 48761 or equal The communications adheres to the industry standards of RS232C and the rate of communications is 9600 baud The recommended maximum distance from the personal computer to the control panel is 50 feet If the required distance is in excess of 50 feet an optional RS 232 extension kit is required contact McQuay A voice quality direct dial telephone line is required if remote access and monitoring of the unit controller is desired The phone line should be terminated with a standard RJ 11C modular phone plug 51 Menu Structure 52 A complete listing of the information stored in the MicroTech controller tree structure is shown in the following tables These tables show the menu numbers and names along with their corresponding menu items and menu item entries as they appear on the MicroTech display The symbol is used where the controller would normally display a numerical value Also included in this figure is the corresponding switch menu for each menu item Notes 1 Status Category Where more than one menu item entry is listed under a menu item the list includes all the entries that can app
70. ons cable should have been installed in accordance with the instructions in the Field Wiring section of this manual This procedure will verify that there are no shorts or stray voltages anywhere in the communications trunk 45 Before beginning verify that the port B connectors disconnected from every controller on the trunk 1 Verify that there is no voltage between any conductor and ground Use a voltmeter to test for voltage at the field wiring terminal block or directly on the port B connector of the level 1 controller With one lead on the control panel chassis ground check for voltage at the and ground terminals There should be no AC or DC voltage see the Signal and Terminal columns of Table 3 If the conductors are properly terminated this check will test for stray voltage throughout the trunk Note If you get a 2 VDC reading it indicates that one or more powered controllers are connected to the trunk These controllers should be located and disconnected 2 Verify that there are no shorts between any two conductors Use an ohmmeter to test for shorts at field wiring terminal block or directly on the port B connector of the level 1 controller For the three combinations of conductor pairs there should be infinite resistance between the conductors If the conductors are properly terminated this check will test for shorts throughout the trunk Note If you find a resistance that is high but les
71. or COM2 and the connector should be a 9 Pin Male d Parallel Printer Port For hard copy custom reports of all accumulated data e Mouse or trackball f Hard Disk Drive 120 Megabyte min A mass data storage area for the operator interface and custom report software g 101 Enhanced Keyboard Required for more advanced functions of the operator interface and custom report software h The computer shall include MS DOS 6 2 or greater Windows 3 1 or greater and all owner s manuals 7 computer shall have an internal time clock that is battery backed to maintain system time and date p computer shall have an internal 9600 Baud Hayes compatible modem if remote access and monitoring of the MicroTech unit controller is desired The modem shall be addressable as COMI or 2 2 Multisync Super VGA Color Monitor For use with the Super VGA graphics 3 Printer 192 CPS Characters Per Second Epson LQ 510 or equivalent Must have the ability of supporting IBM extended character graphics 4 Printer Cable For communications connection between the PC and the printer The computer is used for changing setpoints monitoring data trend logging diagnostics and remotely clearing alarms within the MicroTech system The computer is normally a dedicated personal computer however the operator may choose to exit the Monitor program from time to time to perform other functions such as word processing data manipulati
72. panel When a contact in the digital device makes a return signal is sent back to the Digital Input terminal strip The Input Conditioning Module ICM then conditions the signal The conditioned digital input is then sent to the MCB via a ribbon cable Digital input not read by the MCB If the MCB appears to be functioning properly and the digital input is not being read by the MCB perform the following procedure 1 Try cycling power to the controller by opening and then closing circuit breaker 2 Check the ribbon cable power wiring connector and the field wiring connections from the digital input device Look for bent pins cable on backward or miswiring Restore power after reconnecting all cables and wires 3 Ifthe problem persists try swapping a known good ribbon cable an ADI board or a digital input device Swap these components separately to isolate the problem Remove power from the controller before disconnecting the suspect component and restore power after connecting the replacement component If the problem persists it is likely that the MCB is defective Troubleshooting Analog Outputs Variable voltage or current control signals are sent to analog outputs by the MCB through the Analog Output Expansion Module AOX 4 This can be on the ALS units as the optional fan speed control The MCB sends a voltage or current signal to the AOX 4 via a ribbon cable Jumpers on the AOX 4 determine what type of output will be s
73. play Defaut Range Override Hr 4 NMP Schedule xx N A 1 32 3 4 1 2 3 4 5 7 1 2 3 4 5 3 Day 49 Sameas3apoe 110 Holbox Holiday Date 1 1 Date xxx Jan Dec OM ALSMICRO 2 1 Dur Day s o ta 2052 00 01 3 28 same as 1 and 2 above Up to 14 Holidays Stored Table 36 Three zie Menu Service Test Menu Default Service Test 1 77 Output 0 2 1 Outputi Off o OFF On Off 3 2 EXV 0 760 4 e3EXVPosto MM 0 8 0 760 L 5 4 EXV 0 0 760 6 5 4 OF On Off 7 6 Output5 xxx OFF On Off 8 7 OFF On Off 9 j 8Ouput7 xx 10 9 8 OFF On Off 11 10 9 On Off 12 11 10 OFF On Off 13 12 0 11 OFF On Off 14 OF p C 3i Range 13Output 1 2 14 13 On Off 15 On Off 16 MHb5Outputid xx OFF 17 fiGOutputib ox OFF On Off 18 17Output16 xxx On Off 19 18 177 20 19 18 OF On Off L 21 _ 200utput too OFF On Off On Off On Off 30 moon 31 30 1011010 92 rps OOO
74. problem occurred check the following items gt Make sure the hex switches on each controller set to the correct values gt Make sure the controller has power supplied to it Make sure the communication line is properly connected to port B sure the controller is level 2 by directly connecting the PC to it You must know how to change communications passwords to do this 7 to the next controller and repeat steps 1 through 6 Do this for each controller being connected to the network Note To verify communications more quickly and easily use two people in the commissioning of the network Because some jobs have units located throughout a building having one person perform the commissioning procedure may be difficult When there are two people one person can stay at the PC connected to the controller and the other person can go to each individual unit controller Using a radio or other two way communication equipment they can indicate when a specific controller is connected and whether communications between the controllers is occurring OM ALSMICRO Key Functions OM ALSMICRO The MicroTech keypad consists of twelve pressure sensitive membrane switches Refer to Figure 7 These keys are used to step through access and manipulate the information in the MicroTech controller tree structure The keypad keys are divided into four groups with two or four keys in each Keypad p
75. r 6 will not be enabled unless the circuit capacity is greater than 50 High Pressure Stage Up The controller logic will bring on multiple condenser fan stages if a rapid rise in pressure 15 detected Condenser Fan Stage Down Every four seconds the controller records the difference between the minimum condenser pressure and the actual condenser refrigerant pressure This value is added to the previously recorded values and when the accumulated total is equal to or greater than the stage down setpoint the controller decrements a fan stage The accumulated total is set to zero whenever a fan stage change occurs or the condenser pressure rises inside the dead band Fan stages 5 or 6 will automatically be disabled whenever the circuit capacity falls to 50 or less SpeedTrol Logic When the SpeedTrol option is installed the MicroTech controller will generate an analog signal via the board to directly control the S66DC I variable speed fan motor control The control signal is proportional to the condenser pressure s relative position within the lift pressure dead band Minimum and maximum fan speed is defined by the minimum and maximum lift pressure setpoints When the condenser pressure is below the dead band the fan speed will be set to 096 and when the condenser pressure is above the dead band the fan motor speed will be set to 100 Figure 16 TIE L ERE E 2 2 2 11111 11111 TS EL zx
76. r Compressor Unit 22 Three Compressors Unit 22 Two Compressors Unit 22 Project Ahead Calculation 23 Interstage 23 Anti Cycle Timer 23 Lead Lag of Refrigerant Circuits 24 Electronic Expansion Valve 24 OVELVIEW 24 EXV Superheat Control 24 Forced EXV Position Change 25 EXV Evaporator Pressure Control 25 Chilled Water Reset Options 26 Condenser Fan Control 28 Condenser Fan Staging 28 Head Pressure Control 28 Lift Pressure Dead Band 29 Condenser Fan Stage Up 29 High Pressure Stage Up 30 Condenser Fan Stage Down 30 SpeedTrol Logic see 30 Pumpdown 31 Safety Systems 32 ALS Unit MicroTech Control Alarms 32 MicroTech Controller Test Procedures 36 Keypad Display 37 MicroTech Component Test Procedures 38 Keypad Key Functions 49 Personal Computer Specification 51 MicroTech Menu Structure
77. regulated 5 VDC and 12 VDC supplies provide the correct operating voltage for the sensors Figure 11 Sensor Locations Two Compressor Units Inside o control box on power amp control panels Back of control box Sensor Description Sensor Location Number Reset Evaporator Water Temperature External 4 20 mA Signal OM ALSMICRO 11 12 Figure 12 Sensor Locations 3 Compressor Unit Control Box on Power amp Control Panels 1 One or For Each Table 4 Analog Inputs Compressor Units 512 Suction Temperature 81 ALSMICRO Figure 13 Sensor Locations 4 Compressor Unit Table 5 Analog Inputs 4 Compressor Units Sensor Number Description Evaporator Leaving Water Temperature Low Pressure Transducer Circuit 1 Low Pressure Transducer Circuit 2 High Pressure Transducer Circuit 1 High Pressure Transducer Circuit 42 Evaporator Water Temperature Reset Field Supplied Demand Limit Field Supplied Evaporator Entering Water Temperature Outside Air Temperature Percent Circuit Amps Circuit 1 amp 3 Percent Circuit Amps Circuit 2 amp 4 CT2 Suction Temperature Circuit 1 Suction Temperature Circuit 2 Liquid Line Temperature Circuit 1 Liquid Line Temperature Circuit 2 Low Pressure Transducer Circuit 3 High Pressure Transducer Circuit 3 Suction Temperature Circuit Liquid Line Temperature Circuit
78. rol oeste OM ALSMICRO 82 ALS 125A 204A Staging Output Schematic RELY 7 r 2 2 CONROL 2931 20 kd 2 FEY TC F bi 5 RELAY 11 T 2 1 ALSMICRO ALS 205A 280A Staging Output Schematic T 28 _ mn 33 m ALSMICRO 84 ALS 300A 425A Staging Output Schematic 1304801618 FROM UNE CIR 01071854 ALSMICRO ALSMICRO ALS 125 204 Schematic LIOUE LINE CIRC 462 515 CRC 514 SUCTION TEMP 42 513 SUCTION TEMP CIRC 6512 4 2 lt o e gt analog INPUTS gt 85 86 INPUTS gt ALS 125A 204A MicroTech Schematic continued 54 B B MK 3 53 JE GND 52 CONNECRON FOR 99 kamisa 50 NOW HS PLUG FOR PORTA LARS IN WIRE RACEWAY 8108 a CONNECION FOR UNITS OM ALSMICRO ALSMICRO ALS 205 280 Schematic Es 3 87 88 ALS 300A 425A MicroTech Schematic OM ALSMICRO ALSMICRO ALS Field Wiring 0719740 01 DISCONNECT UNIT MAIN BY OTHERS TERMINAL BLOCK SAM co qur eben 4 GND LUG TO COMPRESSONIS AND FAN MOTOR
79. s than infinite it indicates that one or more non powered controllers are connected to the trunk These controllers should be located and disconnected 3 Verify that the communications wiring is continuous over the trunk and that the field terminations are correct This step is optional but recommended to do it you must know the physical layout of the network s communications trunk Go to the last controller on one end of the daisy chain and place a jumper across the to ground and to ground Remove the jumper and repeat this step for the other two conductor pairs to ground and on to ground If there is continuity for each conductor pair the wiring is continuous and it is likely but not guaranteed that the terminations are correct throughout the trunk If there is no continuity for one or more conductor pairs there may be a break in the trunk or the terminations at one or more controllers may have been mixed up Table 20 Port B Voltages AMP Type Connector Port B RS 485 Acceptable Voltage Signal Reading 3 0 0 3 VDC S 2 0 0 3 VDC 0 0 0 2 VDC Table 21 Network Communications Field Wiring Terminals Network Comm Field Terminal bis d Do Ground ____ 11 11 T11 GND Screw Chiller TB4 54 TB4 53 TB4 55 OM ALSMICRO ALSMICRO Figure 21 Terminal Configuration Pon Commu
80. ser Fan Contactor 9 Condenser Fan ContactorM 25 20 GQomprssorP3Conacor 4 Compressor 3 Top Solenoid Valve feed 22 Compressor 3 Bottom Right Solenoid Valve feed 2 Compressor 3 Bottom Left Solenoid Valve vent 4 Fan Contactor 32 54 CondenserFanContactorM 33 ALSMICRO Condenser Fan Contactor M 34 Condenser Fan Contactor M 34 Optional Hot Gas Bypass SV5 Optional Hot Gas Bypass SV6 Table 12 Digital Outputs 4 Compressor Unit Description Alarm Circuit Chilled Water Pump Relay EXV Control EXV Control Compressor 1 Contactor Compressor 1 Top Solenoid Valve Compressor 1 Bottom Right Solenoid Valve feed Compressor 1 Bottom Left Solenoid Valve vent Compressor 2 Contactor Compressor 2 Top Solenoid Valve feed Compressor 2 Bottom Right Solenoid Valve feed Compressor 2 Bottom Left Solenoid Valve vent Condenser Fan Contactor M 12 Condenser Fan Contactor M 13 Condenser Fan Contactor M 14 Condenser Fan Contactor M 15 Condenser Fan Contactor M 22 Condenser Fan Contactor M 23 Condenser Fan Contactor M 24 Condenser Fan Contactor M 25 Compressor Contactor Compressor 3 Top Solenoid Valve feed Compressor Bottom Right Solenoid Valve feed Compressor 3 Bottom Left Solenoid Valve vent Condenser Fan Contactor M 32 Condenser Fan Contactor M 33 Condenser Fan Contactor M 34 Condenser Fan Contactor M 35 Optional Hot Gas Bypass SV5
81. ssor D SWITCH Pressing the SWITCH key at any time toggles the display between the current menu status control item and the related menu control status item somewhere else in the tree structure For example if this key is pressed while the current menu item is menu item 4A Leaving Evaporator the display shifts to menu item 14A Leaving Evaporator Setpoint This provides for easy review of actual versus setpoint values Menu group The keys in this group are for stepping from menu to menu in the menu tree structure A PREV Pressing PREV shifts the display to the previous menu Note When Menu 1 CHILLER STATUS is currently in the display the first menu in the menu tree structure pressing PREV causes an end of menus message to appear in the display Pressing PREV again causes the display to wrap around to the last menu in the tree structure B NEXT Pressing NEXT shifts the display to the next menu 49 50 Note When the last menu the menu tree structure is currently the display pressing NEXT causes an end of menus message to appear in the display Pressing NEXT again causes the display to wrap around to the first menu in the structure Action Group The keys in this group are for making changes to unit control parameters and setpoints or for clearing alarm conditions Changes do not go into effect nor are they remembered until the ENTER key is pressed Note Before a change to a p
82. superheat setpoint With a decrease in circuit capacity the electronic expansion valve position will be closed by a fixed percentage of its current position Table 13 Staging Up When Staging Up To 50 75 100 Table 14 Staging Down When Staging Down To Close 100 75 50 25 EXV Evaporator Pressure Control The electronic expansion valve control will maintain a constant superheat for suction line temperature up to 60 F For suction line temperatures greater than 61 F the expansion valve control logic will maintain a constant evaporator temperature to avoid overloading the compressor motor The control point will be the Evap Temp setpoint default 50 F and the control method will be the standard MicroTech Step and Wait algorithm When the suction line temperature drops below 57 F the MicroTech logic will resume normal superheat control OM ALSMICRO 25 Chilled Water Reset Options 26 Chilled Water Reset Remote 4 20mA The controller resets the chilled water setpoint based on an external 4 to 20mA signal At 4mA or less no reset will occur At 20mA the chilled water setpoint will be reset by an amount equal to the value stored in the Maximum Reset setpoint The reset schedule is linear and may be calculated using Figure 14 Figure 14 Chilled Water Reset Schedule pl z 3 m 57 8 9 10 71 12 13 12 15 16 17 18 19 20 F xterr al A
83. t Board The resistance should not be less than 3000 ohms If the resistance is greater than the acceptable value go to step 3 If the resistance is less the acceptable value the Output Board is defective 43 44 LED lit output energized If the LED of a suspect relay is lit but the load connected to it is not energized and everything is intact between the MCB and the control side of the relay perform the following procedure to isolate the problem 1 Verify that 24 120 VAC power is present at the suspect output s screw terminal on the Output Board 2 Remove power from the controller by opening Swap the suspect relay with a known good relay Try to choose a relay that will not affect unit operation Restore power by closing If the output load energizes the suspect relay is bad Replace the relay If the output load does not energize when LED is lit again check the load circuit wiring and components Output energized LED not lit If the LED of a suspect relay is not lit but the load connected to it is energized either the solid state relay or the MOV is bad The solid state relay output and the MOV which are in parallel can both fail closed Perform the following procedure to isolate the problem 1 Remove power from the controller by opening Pull the solid state relay from the suspect output s socket 2 Restore power by closing If the output load remains energized when
84. tdown circuit and liquid injection if compressor fails to start due to a possible open contactor FailEXV Evap Pressure fails to rise after Exv is opened LoChrg To prevent operation with bad EXV or severe undercharge 40psig is a memory During startup the EXV will not open until the suction pressure falls location 60sec to 40 psig within a default 60 seconds If these two settings are not timer is adjustable non shutdown alarm will occur on Monitor and Keypad To alert service tech that circuit is not pumping normally FailLow Memory location Evaporator Pressure fails to rise above the Freeze stat setpoint after Ambient 180seconds To prevent operation with evaporator pressure too low during start up 32 OM ALSMICRO Alarm Desorption and Reason tor alarm Display Down Setpoints 11 Liquid Auto Memory location 20 seconds with no liquid at liquid presence sensor or 29 seconds Start Manual with 9 occurrences of liquid The first occurrence is auto reset while the second is a manual reset To prevent overheating of the screw due to lack of liquid feed 12 Liquid Manual Memory locations 12 seconds without liquid at 100 75 load 30 seconds w out for time w out liquid liquid at 50 and 25 To prevent overheating of the screw due to lack of liquid feed during running 13 FreezeStage Auto Keypad and Monitor The evaporator pressure must remain below the Fr
85. te relay a LED 5 amp fuse and an MOV metal oxide varistor Normally when the MCB commands an output to energize the solid state relay turns on and the LED will glow The output of each solid state relay is in series with a 5 amp fuse These fuses resemble small resistors and are located on the board adjacent to the relays they serve The fuses are pressed into place They can be removed with needle nose pliers The MOV which is located on the underside of the output board protects the solid state relay from high transient voltages MOVs are part of the output board and cannot be replaced Following are troubleshooting procedures for various symptoms of output board problems Note should be possible to determine whether a solid state relay is defective by using these procedures However if you need more information on troubleshooting them refer to Troubleshooting Solid State relays below OM ALSMICRO ALSMICRO Figure 18 Output Board Relay Socket 0 Fuse WARNING Electric shock hazard cause severe injury or death Even when power to the panel is 2504 5010 Hz off solid state relay socket 120V H7 terminals 1 and 2 on the output board could be connected to Test Resis or high voltage see Figure 5 EXV 14 350680 Ohm board Avoidthem 0 One LED out If one of the Output Board LEDs fails to illuminate when the MCB is commanding the associated output to energize perform the follo
86. ter than 60 F when the unit is started one additional condenser fan stage will be energized If the outdoor ambient temperature is greater than 80 F two additional fan stages will be energized ALS unit BERs are maximized by not allowing the last condenser fan stage to operate when the unit capacity is 2596 and the condenser pressure is below 200 psi The last fan stage will operate if the condenser pressure is above 220 psi at 2596 unit capacity Lift Pressure Calculation The expansion valve determines the minimum acceptable lift pressure At low tonnage capacities a minimum lift pressure of approximately 60 psid must be maintained At high tonnage capacities a higher lift pressure must be maintained to provide proper refrigerant flow through the expansion valve Refer to the following table for the lift pressure values maintained at various unit capacities Individual head pressure setpoints are provided at 25 50 and 100 circuit capacity to optimize chiller operation For operation at 7596 capacity and greater with outdoor air temperatures less than 60 F the minimum lift will automatically be reset downward The maximum available reset at 100 capacity is 40 psid while the maximum reset at 75 capacity is 20 psid Table 16 Lift Pressure Values Capacity Adjustment Range 50 psig 80 120 100 psig 50 130 110 psig 100 140 psig 110 160 ALSMICRO 15 Min List 144 lt 100
87. tor and control the unit It receives input from the ADI Board and sends commands to the Output Board to maintain the unit s optimum operating mode for the current conditions Status lights are mounted on the control board to indicate the operating condition of the microprocessor Figure 2 MCB1 Analog Digital Input Board ADI Board The ADI Board provides low voltage power for the temperature and pressure sensors It also provides electrical isolation between the Microprocessor Control Board and all 24V switch inputs LEDs are furnished on the board to give a visual indication of the status of all digital inputs analog and digital signals from sensors transducers and switches are received by the ADI Board and then sent to the Microprocessor Control Board for interpretation 3 ADI d TH 20 s 655555555595055955 0 The Output Board contains up to 24 solid state relays which are used to control all compressors condenser fans solenoid valves and alarm annunciation It receives control signals from the Microprocessor Control Board through a 50 conductor ribbon cable 6 OM ALSMICRO Figure 4 Output board Electric Expansion Valve Board EXV Board Each EXV Board will directly control up to two electronic expansion valves The boards may be cascaded together for units with more than two EXV s Control instructions for the boards are generated by the M250 contr
88. uge 21 Opened CE LowAmbStat 21 Cooling Cap f PumpingDown CT Cid 1 Same as above Circi3Status rus O CrewaStaus T OO O 7 1 Same as Cir 3 above E 20 Ent Evap o i Circ t Pres s TE psi kPa F C 1 Cnd psi kPa F C ___________ MncondPr TP 4 5 0 6 jCondFanStage t Circ 2 Pres s pi 1 Sameasabove d OM ALSMICRO Circ 3 Pres s 2 1 Sameasabove O Circ 4 Pres s 2 1 JSameasabove 11 OM ALSMICRO 69 Table 39 Four Compressor Menu Status Continued Menu Hem Display Detam Rane Crem Temps CSCS C 2 5 Super C CC r 4 E A 6 Tia Chilleramps 11 20 1 Marois 2 24 PotRLA HH 0 00000 2 3 4 5 f 25 6 7 f 75 paper 8 100 ERR 9 10 2 50 92 75 o 12 2 100 x 15 109 2562000 14 3 50 PU 4 53 75 HH ee 16 3 100 17 4 25 x j
89. uit capacity of 2590 to 50 the superheat setpoint will be 8 0 F For circuit capacity of 75 to 100 the superheat setpoint will be 10 0 F When the chiller control panel is powered up the expansion valve will be driven closed 800 steps This ensures that the valve is fully closed prior to a call for cooling When all refrigerant circuit safeties are satisfied the controller will initiate a start sequence When the start sequence reaches open solenoid the expansion valve will be driven open to the First Open setpoint default 300 steps The current suction line temperature is compared against the Suction Line Temperature setpoint evaporator temp plus superheat spt to calculate superheat error Err The current suction line temperature is also compared with the previous reading to calculate delta superheat error Derr These two error values are used to determine the magnitude and direction of the expansion valve positioning signal A new valve positioning signal is calculated every 10 seconds however the OM ALSMICRO interval at which these signals are issued to EXV board is dependent on the magnitude of the required positional change If no change is required the internal will be 60 seconds Forced EXV Position Change With an increase in circuit capacity the electronic expansion valve position will be opened by a fixed percentage of its current position This change will not occur if the superheat is less than 4 F below the
90. urs and the number of starts The circuit with the fewest number of starts will be started first If circuits are operating and a stage down is required the circuit with the most operating hours will cycle off first Manual Lead Lag The operator may override automatic circuit selection by manually selecting the lead circuit via the keypad or monitor When the setpoint equals auto the lead compressor is selected by the MicroTech controller based upon which circuit has the least operating hours Regardless of the mode selected if the lead circuit cannot operate due to an alarm condition or if off on cycle timers the controller will switch to the lag circuit Electronic Expansion Valve 24 Overview McQuay screw compressor chillers are supplied with Sporlan SE series electronic expansion valves The MicroTech controller generates valve positioning signals to maintain refrigerant circuit superheat to within 1 5 F of the superheat setpoint Valve positioning signals are converted to actuator step pulses by the EXV board which in turn drives the valve s 3 phase DC stepper motor open or closed as required A control range of 0 steps full closed to 760 steps full open is available to provide precise control of the valve position EXV Superheat Control The electronic expansion valve position will be adjusted to maintain the refrigerant circuit s superheat setpoint Superheat setpoints are based on refrigerant circuit capacity For circ
91. various options that may be installed on the chiller Off Conditions With power supplied to the unit 115 VAC power is applied through the control fuse F1 to the compressor casing heaters the compressor motor protector circuits the primary of the 24V control circuit transformer and optionally the evaporator heater HTR5 The 24V transformer provides power to the MicroTech controller and related components With 24V power applied the controller will check the position of the front panel System Switch S 1 If the switch is in the stop position the chiller will remain off and the display will indicate the operating mode to be OFF SystemSw controller will then check the PumpDown Switches If any switch is in the stop position that circuit s operating mode will be displayed as OFF RemoteComm if this operating mode is in effect If an alarm condition exists which prevents normal operation of both refrigerant circuits the chiller will be disabled and the display will indicate OFF AllCompAlarm The MicroTech controller allows the operator to manually set the chiller to an off mode via the keypad The display indicates this operating mode with the message OFF ManualMode Assuming none of the above Off conditions are true the controller will examine the internal time schedule to determine if the chiller should start The operating mode will be OFF TimeClock if the time schedule indicates an off time period Start up If none of t
92. ving water setpoint is never set to a OM ALSMICRO ALSMICRO value greater than return water setpoint is never set to value less than the actual leaving chilled water setpoint Remote Demand Limit The controller will limit the total number of stages based on an external 4 to 20mA signal regardless of the amount of cooling actually required 4mA or less signal will enable all stages while a 20mA signal will allow only 1 stage to operate The effect of the reset signal may be calculated by using Figure 15 Network Demand Limit Unit demand limit via network communication may be selected if desired The chiller controller receives a demand limit signal from the network master panel in the range of 096 to 10096 with 0 equaling no limit Keypad Selectable Demand Limit In the menu Demand Limit set Manual Demand Stage which is below the maximum available for the unit Soft Loading The soft loading feature limits the number of cooling stages which may be energized by the controller to prevent unnecessary electrical demand and possible over shoot of the desired leaving water temperature Soft loading is typically used during morning start up When the controller enters the Cool Staging mode of operation the controller will start a count down timer to indicate how long the unit has been in the cool staging mode The maximum number of cooling stages will be limited to the soft load setpoint until the soft load count
93. wing procedure 1 Remove power from the controller by opening Swap the suspect relay with a known good relay Try to choose relay that will not affect unit operation Restore power by closing If the LED does not light go to step 2 If the LED lights the suspect relay is defective 2 Remove power from the controller Check the ribbon cable and connections between the OB and the MCB Look for bent pins If the cable and connections are intact go to stop 3 3 Remove the relay from the suspect socket Install a 330 680 ohm resistor between terminals 3 and 5 as shown in Figure 5 EXV board Restore power by placing to the ON position The LED should light regardless of the controller s command If the output LED illuminates it is likely that the MCB is defective If the LED does not illuminate the output board is defective All LEDs out If the MCB is commanding at least two outputs to energize and none of the Output Board LEDs are lit perform the following procedure 1 Verify that 5 VDC is present at the Output Board s power terminals If 5 VDC is not present go to step 2 If 3 VDC is present check the ribbon cable and connections between the output board and MCB Look for bent pins If the cable and connections are intact the Output Board or the MCB is defective Remove power from the controller by placing CB1 to the OFF position Disconnect at least one wire from the power input terminals of the Outpu
94. xx 9 2 759 momma Compr Starts 1 i Total axxxxxx 22 2 Total xxxxxx 00000001 Outdoor xxx x F C CST Short F C Table 23 Two Compressor Menu Control Mode Menu Dispay Range Control Mode Manual Unit Off Manua unto j Manai Staging PP 1 2 Orco Service Testing Manual Stage xx 51 9 2 ALSMICRO ALSMICRO Table 24 Two Compressor Menu Set Points Item Display Default Values for R 22 Refrigerant 1 Sptaxxx xF C NotChangeabe 3 OnriBand xx C 30 145 4 StaUpD T xt CO 20 059080 5 5 05 04 6 MaxPullDn xxF C 10 42 None Return 4 20 Ice Network Outdoor RestSgooama MexcHWRstsxarE 045 06160909504 78 00 7 13 20 90 4 406109600 9 10 60 5 AmbStage xx x F 30 80 Menu oftLoad Spts 1 Timelet xxmn J 0 0 254 0 254 So dMaStg x 23 28 O __ CompresorSPT 1 2 InterStg xxxsec 1 60240 6 60 09 Head Pres Spt 1 25 100 80120 MinLift 50 L 10 50 17 Min

MicroTech Control System for Air

Contents

Download Pdf Manuals

Related Search

Related Contents