Motor/System
Status Description
Trigger
Method
Troubleshooting
RotorStarting
TorqueFault
INS
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Atlowspeed(startup)rotorangularpositionisnotatcorrectvalueforagivenspeed,causedbylow
shaftmagnetstrength,liquidfloodedcompressorordamagedtouchdownbearings/physicalcontact
ofrotatingcomponents.
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Ifthisfaultoccursthreetimeswithina30-minuteperiod,aLock-OutFaultwilloccur.
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IffaultoreventlogsshowoccurrenceofStartingTorquefaultafteroneInverterError,theInverter
shouldbeverifiedandmayrequirereplacement.RefertoInverterErroronpage260orMotor
SinglePhaseOvercurrentFaultonpage260.Shaftorbearingsmaybemechanicallydamagedand
unabletoturn.
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Verifythebearingcalibrationandlevitation.RefertoSection5.3BearingCalibrationonpage263.
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VerifytheInverter.RefertoSection4.22.2InverterVerificationonpage176.
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VerifytheStator.RefertoSection4.23.4MotorVerificationonpage195.
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ReviewFaultandEventLogdetailstodetermineconditionsrelatedtothefault.
LowInverter
CurrentFault
AFT
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Suggeststhecompressorhasnoload,verifyloadisavailable.Minimummagnetizingpowernot
absorbedforgivenspeedattheInverter.
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Compressorisnotpumpinggas.Usuallyseeninopen-airoperation.
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ReviewtheFaultLogforthelevelofMotorCurrentinthefaultrecord.
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ZeromotorcurrentatzeroRPMindicatesaproblemwiththeInverter.VerifytheInverter.Referto
Section4.22.2InverterVerificationonpage176.
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VerifytheStator.RefertoSection4.23.4MotorVerificationonpage195.
DCBus
Under/Over
VoltageFault
DFT
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At0RPM:IfthemeasuredDCBusvoltageislowerthanSoftStartchargevoltage,aDCbusvoltage
faultisrecorded.All3-phasevoltageinformationdisplayedintheSMTiscalculatedfromDCbus
voltage,asmeasuredbytheInverter.
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Typically,thisfaultisrecordedwhenpowertothecompressorisremoved.
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MeasureandcomparetheincomingmainACvoltagetothecompressorratedvoltage.
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ComparethemeasuredvoltagestothedisplayedreadingsintheCompressorMonitorToolandFault
andEventLogdetailstodetermineconditionsrelatedtothefault.
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MeasuretheDCbusvoltageusingtheDCBusTestHarness.RefertoSection1.10.1General
VerificationandInstallationoftheDCBusTestHarnessonpage26.
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VerifytheSoftStart.RefertoSection4.14.2SoftStartVerificationonpage115.
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VerifytheSCRs.RefertoSection4.18.2SCRVerificationonpage142.
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VerifytheconnectionstotheInverter.RefertoSection4.22.2InverterVerificationonpage176.
24VDC
Under/Over
VoltageFault
RFT
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Suggeststhemeasured24VDCsupplyvoltageisoutofrange.
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Measurethe24VDCtestpointsattheBackplane.RefertoSection4.25.2.2BackplaneVerificationon
page214.
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ComparethemeasuredvoltagestothedisplayedreadingsintheCompressorMonitorToolandFault
andEvent
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ReviewFaultLogdetailstodetermineconditionsrelatedtothefault.
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Ifthemeasuredvoltageisincorrect,verifytheDC-DCConverter.RefertoSection4.24.2DC-DC
ConverterVerificationonpage204.
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Determinethatoneofthemodulesisnotdrainingenergy.RefertoSection5.5.2Determiningthe
CauseofanEnergyDrainonpage271.
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Ifthefaultoccurswhenthecompressorisgiventhedemandtorun,theInvertermaybecausingthe
24VDCfault.
LowMotorBack
EMFFault
DFT
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Thecalculatedmagneticstrengthoftheshafthasfallenbelowtheminimumlimit.Thiscanbea
temporaryeffectduetohighloadandelevatedtemperatures(willrecoverwhencavitytemperature
cools)orduetoapermanentdemagnetizationoftheshaft.
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Ifthisfaultoccursthreetimeswithina30-minuteperiod,aLock-OutFaultwilloccur.
M-SV-001-EN Rev. H-1/23/2023 Page 261 of 294