10
WARNING
Hazardous
voltage
Power Supply and Wiring
Section 6 (continued)
Delta/Delta with grounded legAnothercommoncongurationprovidingvoltagerebalancingwithnophaseshiftbetweeninputandoutput.
Again,dependingontheoutputconnectionsfromthedrivetomotor,thegroundedneutralmaybeapathfor
commonmodecurrentcausedbythedriveoutput.
Ungrounded secondaryGroundingofthetransformersecondaryisessentialtothesafetyofpersonnelaswellasthesafeoperation
ofthedrive.Leavingthesecondaryoatingcanpermitdangerouslyhighvoltagesbetweenthechassisofthe
driveandtheinternalpowerstructurecomponents.Inmanycasesthisvoltagecouldexceedtheratingofthe
EMClterandinputMOVprotectiondevicesofthedrivecausingacatastrophicfailure.Inallcases,theinput
powertothedriveshouldbereferencedtoground.Ifthetransformercannotbegrounded,thenanisolation
transformermustbeinstalledwiththesecondaryofthetransformergrounded.
Warning
Ifapowersystemwithanungroundedsecondaryisused,thelinetogroundEMClter
componentsandlinetogroundMOVprotectionmustbedisconnectedordamageto
thecontrollercanresult.
ToremovethelinetogroundEMCltercomponents,locatethejumpershownbelow.Thejumperisontheleft
handsideofthecontrolleronthemainboard.Movetothedisconnectedpositionshownbelow.