Wait, the compressor and drive is a device or a pair of devices right next to each other, assembled in a factory, and made out of metal. Why does the quality of the connection between the hunks of metal and the planet have any effect?
VFDs can produce nasty waveforms, and there are cases where “grounding” could be a big deal, but I think that the wiring of the ground terminal of the power supply is only relevant at all when it’s involved in the connection between the drive and the motor. So, for example, if you have a VFD that is far away from a motor, then you would want to make sure the VFD and the motor’s grounds are connected to each other and maybe even that the VFD’s supply neutral (average of the phases) is reasonably close in voltage to ground, keeping in mind that there may not be an actual neutral wire connected to the VFD, and that the motor’s ground is well connected to the VFD’s ground. By modern standards one should use actual VFD cable and terminate it properly.
VFDs can produce nasty waveforms, and there are cases where “grounding” could be a big deal, but I think that the wiring of the ground terminal of the power supply is only relevant at all when it’s involved in the connection between the drive and the motor. So, for example, if you have a VFD that is far away from a motor, then you would want to make sure the VFD and the motor’s grounds are connected to each other and maybe even that the VFD’s supply neutral (average of the phases) is reasonably close in voltage to ground, keeping in mind that there may not be an actual neutral wire connected to the VFD, and that the motor’s ground is well connected to the VFD’s ground. By modern standards one should use actual VFD cable and terminate it properly.
https://www.southwire.com/medias/sys_master/related-pdfs/rel...