Danfoss TTS400

4.18 Silicone-Controlled Rectifier
TheACinputvoltageisconnectedtotheSCRsbytheMainsInputbusbars.TheSCRsareusedtoconverttheAC
voltageintoDCvoltage.SCRsmaintainthehighvoltageDCbusnecessarytoprovidepowertotheInvertertorun
thecompressormotor.
UsingboththeACinputvoltageandtheDCvoltageoutputfromtheSCRs,theSoftStartBoardgeneratesthegate
signalandoutputspulsesof0-12VDCtotheSCRstocontrolthein-rushcurrentwhenpowerisinitiallyappliedto
thecompressor.ThisisusedwhiletheDCcapacitorsarechargingup.
TheDCbusvoltageoutputfromtheSCRsisapproximately1.35timesthatoftheACinputvoltage(460-900VDC).
Therearetwo(2)differentstylesusedforthecompressors.RefertoFigure4-139SCRStylesforthevisualdifferences.

Figure 4-139 SCR Styles
4.18.1 SCR Connections
RefertoFigure4-140SCRConnections-TTS300/TGS230andFigure4-141SCRConnections-TTS/TGS/TTH/TGHRev.
FandEarlier(ExceptTTS300/TGS230)onpage142tolocatethefollowingconnectionstotheSCRs:
l
ACinputtoSCR
l
SCRGatecablestoSoftStart
l
SCRtoDCbus

Figure 4-140 SCR Connections - TTS300/TGS230
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M-SV-001-EN Rev. H-1/23/2023 Page 141 of 294