Are there any special considerations for motor grounding when using VFDs?
Yes. The motor should have an appropriately size grounding conductor that is terminated at the dedicated VFD terminal. The motor ground conductor of a VFD has an induced current level that must be filtered through its source of origin. Thus a grounding connection needs to be made from the motor to the provided ground terminal on the VFD. An additional grounding terminal on the VFD connects to the common terminal board (comm. TB), which ultimately goes to the building grid ground. The above grounding procedures are necessary in order to reduce interference to the control circuitry as a result of the ground current induced from the drive.
