PowerFlex 750-Series AC Drives User Manual

Installation/Wiring 1-9If any of these conditions exist, additional source impedance is required.The total input impedance is a function of all transformers, cabling, andreactors (if used) that supply power to the drive. The impedance can becalculated using the information supplied in Wiring and GroundingGuidelines for Pulse Width Modulated (PWM) AC Drives, publicationDRIVES-IN001.Grounding RequirementsThe drive Safety Ground-PE must be connected to system ground.Ground impedance must conform to the requirements of national and localindustrial safety regulations and/or electrical codes. The integrity of allground connections should be periodically checked.Recommended Grounding SchemeA single point (PE only) grounding scheme should be used. Someapplications may require alternate grounding schemes, refer to Wiring andGrounding Guidelines for Pulse Width Modulated (PWM) AC Drives,publication DRIVES-IN001, for more information. These applicationsinclude installations with long distances between drives or drive line-ups,which could cause large potential differences between the drive or line-upgrounds.For installations within a cabinet, a single safety ground point or ground busbar connected directly to building steel should be used. All circuitsincluding the AC input ground conductor should be groundedindependently and directly to this point/bar.Figure 1.7Typical GroundingR (L1)S (L2)T (L3)U (T1)V (T2)W (T3)PESHLDShield Termination - SHLDThe Shield terminal (see page 1-15) provides a grounding point for themotor cable shield. It must be connected to an earth ground by a separatecontinuous lead. The motor cable shield should be connected to thisterminal on the drive (drive end) and the motor frame (motor end). Use ashield terminating or EMI clamp to connect shield to this terminal.PowerFlex 750-Series User Manual – Publication 750-UM001C-EN-P – September 2009