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9. Usinganappropriately-ratedvoltmeterwiththe1000VDCrangeselected,insertthepositivevoltmeter

leadintotheDC(+F)testharnesslead,andthenegativevoltmeterleadintotheDC(-)testharness

lead.IfthevoltagecorrespondstoTable1-2ExpectedDCBusVoltage,theDCbusvoltageiscorrectand

HVDC(F1)fuseontheSoftStartisintact.ThiswouldimplythattheSoftStartandSilicon-Controlled

Rectifiers(SCRs)arefunctioningcorrectly;proceedtoStep12.Ifvoltagereads0,gotoStep10.

Table 1-2 Expected DC Bus Voltage

Compressor Nameplate AC Voltage Acceptable AC Voltage Range Expected DC Bus Voltage Range

575VAC 518-632VAC 700-853VDC

460VAC 414-506VAC 559-683VDC

400VAC 360-440VAC 486-594VDC

380VAC 342-418VAC 462-564VDC



10. LeavingtheDC(-)testleadinplace,relocatethepositive(+)testleadtoDC(+).IfDCvoltageis

consistentwithTable1-2ExpectedDCBusVoltage,thiswouldimplythattheSoftStartandSCRsare

workingcorrectly,buttheHVDCfuse(F1)ontheSoftStartisanopencircuit,refertoSection4.24High

VoltageDC-DCConverteronpage204toverifytheDC-DCConverter.

11. IftheDCvoltageisnotpresentorisnotconsistentwithTable1-2ExpectedDCBusVoltage,the

incomingACvoltageshouldbeverifiedtobebetweentheacceptableACVoltageRangelistedinTable

1-2ExpectedDCBusVoltage.AdditionallytheF2,F3,F4,F5,andF6fusesneedtobeverifiedaswellas

theSCRDiodesandSCRGates.RefertoSection4.18Silicone-ControlledRectifieronpage141for

testingdetails.

12. ForthePottedDC-DC,resetmultimeterscalingtoread15VACandconnecttothe15VACleadsofthe

DCBusTestHarness.Ifthereadingiszero,isolatethethree-phasesupplyinaccordancewithSection

1.8ElectricalIsolationonpage22.Whenaccessissafe,removethefour(4)fastenersthatholdtheSoft

Startinposition,andcheckfusesF2,F3,F4,F5,andF6forcontinuity.Ifanyfuseisfoundtobeanopen

circuit,replaceitandreturntoStep6.

13. Ifthe15VACisnotpresentforthePottedDC-DC,replacetheSoftStart(refertoSection4.14.3Soft

StartRemovalandInstallationonpage117).Ifthe15VACiscorrect,proceedtothenextstep.

14. Whenfinished,removetheDCBusTestHarness.RefertoSection1.10.4GeneralDCBusTestHarness

Removalonpage31.



• • • DANGER! • • •

TheDCbustestharnessisnotdesignedtobeleftinthecompressorduringnormaloperation.Whenchecksarecomplete,disconnectand

removethetestharness.



M-SV-001-EN Rev. H-1/23/2023 Page 29 of 294

Danfoss TTS400 User Manual

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