User guide

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Corporate Office: 724.584.5500  Instant Access 24/7 (Parts and Service): 800.458.1960  Parts and Service: 814.437.6861
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Components
ChilledWaterReturnTemperatureSensor
Thetemperaturesensorisinthereturnfluidpipingandsensesthetemperatureofthechilled
waterenteringtheevaporator.ThechilledwaterintemperatureisontheHMIscreen.This
probeisdirectlyinthefluidstream,thereisnotasensorwellincluded.
ChilledWaterSupplyTemperatureSensor
Thistemperaturesensorisinthechillerreservoirandittransmitsthechilledwatersupply
temperaturetothePLC.Thereadingfromthissensorisusedasthecontrolvariableforthe
chiller’stemperaturecontrol.Thereadingiscomparedtothesetpointandthehotgasbypass
valveispositionedto
drivethetemperaturereadingtowardsthesetpoint.TheHotGasBypass
Valveisopenedtowards100%whenthetemperatureisbelowsetpoint,andisclosedtowards
0%whenthetemperatureisabovesetpoint.Thisprobeisdirectlyinthereservoir,thereisnot
asensorwellincluded.
Compressor
Thechillerisequippedwithahermeticscrollcompressor.Boththecompressorandthemotor
areencasedtogetherandsolidlymountedinthecabinet.Thecompressorisunidirectionaland
willonlypumprefrigerantwhenproperlyphased.Thecoolrefrigerantsuctiongascoolsthe
motorwindings,andthereisaninternalthermaloverloadtoprotectthewindingsfrom
overheating.Thecompressorislubricatedwithoilthattravelsthroughoutthesystemwiththe
refrigerant.Chillerswithcapacitiesof20tonsormoreareequippedwithtwocompressorsin
tandem.Thecompressorsareabletobeoperatedindependentlyiftheheatloadisnotlarge
enoughtorequirebothcompressors.
CompressorElectronicMotorModule
Thecompressorisfittedwithanelectronicprotectiondevicelocatedwithinthecompressor
motorterminalbox.ThisdevicemonitorsthetemperatureofthemotorwithaseriesofPTC
sensorsmountedinthemotorwinding,thedischargegasandoiltemperatureviatheoil
temperaturesensor,motorrotation,andphasefailure.
Atthetrip‐pointtemperature,the
compressorshutsdownimmediately.Ifanincorrectphaserotationorphasefailureoccurs
withinthefirstfivesecondsafterstart‐up,thecompressorwillalsoshutdownimmediately.If
repeatedphasefailuresoccuroranyotherfaultlistedaboveoccurs,themodulelocksout
and
requiresamanualreset.Themainpowermustbeoffforatleastfivesecondstoresetthe
module.Ifatemperaturefaultoccurred,thecompressormustalsofirstcooldownbeforethe
modulewillreset.
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