I've been browsing various manufacturer termination instructions and forums, and I'm seeing conflicting information regarding shield termination locations. I'm looking to run 3 conductor VFD cable from the drive to a reflective wave reducer, then disconnect switch, then motor. I'm not sure if a shield termination kit should be used at the drive only, at the drive and motor only, or at all locations.
VFD Cable Shield Termination Locations
- Thread starter thump3r
- Start date
OldSparks
Senior Member
- Location
- Vacaville CA USA
- Occupation
- Retired: Electrician, Submarine Electronics (21 years), Potable water system maintenance boss (21 years).
Given that the disconnect is a passive device, I would terminate both ends between the VFD and filter, both ends from filter to disconnect, then only the disconnect end leading to the motor. No termination of shield at the motor.
jtinge
Senior Member
- Location
- Hampton, VA
- Occupation
- Sr. Elec. Engr
Termination of VFD motor cables should not be treated the same as termination of control and signal circuits. Where control and signal circuits are typically terminated at the source end only, most VFD manufacturers recommend or require that VFD motor cables terminate the shield at both the motor end at the motor terminal box and at the PE terminals at the VFD end with no intermediate interruptions or intermediate terminations. Where intermediate terminations are required (such as the installation of a disconnect switch), continuity of the shield from the VFD should be maintained through the intermediate connection all the way to the motor. Otherwise reduced EMI mitigation and uncontrolled common mode currents passing through the motor bearings can be an unintended consequence.