Danfoss TTS400

4.23.4 Motor Verification
• • • CAUTION • • •
Donotattempttoperformaninsulationtestonacomponentundervacuum.Thiscancauseinsulationbreakdownorfailureduringthe
testingprocess.
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4.23.4.1 Stator Insulation Verification
1. IsolatethecompressorpowerasdescribedinSection1.8ElectricalIsolationonpage22.
2. RemovetheSoftStart.RefertoSection4.14.3SoftStartRemovalandInstallationonpage117.
3. RemovetheCopperTubesthatconnectthemotorbusbarstotheInverter.

• • • CAUTION • • •
AfaultyStatorcancausetheInvertertofail.

4. Usingamega-ohmmetersetfor1000VDCmeasurements,connectthered(+)mega-ohmmeterleadto
oneofthethreemotorbusbarsandtheblack(-)mega-ohmmeterleadtothecompressorhousing.
Themeasuredvalueshouldbegreaterthan100mega-ohms.Ifthemeasuredvaluedoesnot
correspondtotheexpectedresistance,thentheStatorinsulationisfaultyandthecompressorneedsto
bereplaced.
5. RepeatStep4fortheremainingtwo(2)motorbusbarstoensureallwindingsareintact.
4.23.4.2 Stator Resistance Verification
ToverifytheStatorresistance,completethefollowingsteps:
1. IsolatethecompressorpowerasdescribedinSection1.8ElectricalIsolationonpage22.
2. RemovetheSoftStart.RefertoSection4.14.3SoftStartRemovalandInstallationonpage117.
3. RemovetheCopperTubesthatconnectthemotorbusbarstotheInverter.
4. Usingamultimetersetforresistancemeasurements,placethered(+)multimeterleadononeofthe
three(3)motorbusbarsandtheblack(-)multimeterleadonanothermotorbusbarandrecordthe
results.Themeasuredvalueshouldbelessthan1Ωbutnotzero.Ifthemeasuredvalueis0.0Ωor
greaterthan1Ω,thentheStatorwindingisfaultyandthecompressormustbereplaced.
5. RepeatStep4fortheremainingcombinationsofmotorbusbarstoensureallwindingsareintact.
4.23.4.3 Stator Thermistor Resistance Verification
1. IsolatethecompressorpowerasdescribedinSection1.8ElectricalIsolationonpage22.
2. DisconnecttheDCsupplycableharnessfromthemotorthermistorterminals.RefertoFigure4-217
ConnectiontoStatoronpage194.
3. Usingamultimetersetforresistancemeasurements,placethered(+)multimeterleadononemotor
thermistorterminalandtheblack(-)multimeterleadontheothermotorthermistorterminal.The
measuredvalueshouldcorrespondtotheexpectedresistance(150-300Ωat70°F(21°C)outlinedin
Figure4-218StatorThermistorR/TCurveonpage196.Ifthemeasuredvaluedoesnotcorrespondto
theexpectedresistance,thentheStatorthermistorisfaultyandthecompressormustbereplaced.
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M-SV-001-EN Rev. H-1/23/2023 Page 195 of 294