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10
WARNING
Hazardous
voltage
Power Supply and Wiring
Section 6 (continued)
Delta/Delta with grounded leg
Anothercommoncongurationprovidingvoltagerebalancingwithnophaseshiftbetweeninputandoutput.
Again,dependingontheoutputconnectionsfromthedrivetomotor,thegroundedneutralmaybeapathfor
commonmodecurrentcausedbythedriveoutput.
Ungrounded secondary
Groundingofthetransformersecondaryisessentialtothesafetyofpersonnelaswellasthesafeoperation
ofthedrive.Leavingthesecondaryoatingcanpermitdangerouslyhighvoltagesbetweenthechassisofthe
driveandtheinternalpowerstructurecomponents.Inmanycasesthisvoltagecouldexceedtheratingofthe
EMClterandinputMOVprotectiondevicesofthedrivecausingacatastrophicfailure.Inallcases,theinput
powertothedriveshouldbereferencedtoground.Ifthetransformercannotbegrounded,thenanisolation
transformermustbeinstalledwiththesecondaryofthetransformergrounded.
Warning
Ifapowersystemwithanungroundedsecondaryisused,thelinetogroundEMClter
componentsandlinetogroundMOVprotectionmustbedisconnectedordamageto
thecontrollercanresult.
ToremovethelinetogroundEMCltercomponents,locatethejumpershownbelow.Thejumperisontheleft
handsideofthecontrolleronthemainboard.Movetothedisconnectedpositionshownbelow.