VFD EMI mitigation

Could you (anyone interested) shed some light on the difference between connecting shield to ground on motor side only VS both sides (VFD and Motor). I read conflicting recommendations and my experience with several OEMs is to connect motor side only while drive manual stated they should be connected both sides.



Thanks

POWER wiring shields should be grounded at both ends. You are creating a “Farraday shield” around your conductors to prevent them from becoming radio broadcasting antennae, bleeding EMI and RFI all over your facility.

If the shielded wire is for control, signals or communications, you only ground ONE END, preferably the source end, so as to avoid creating ground loops that might interfere with your low energy circuit.

lesmar96 said:

@kallileo

I was curious if you were able to implement any of the changes yet and what/if made any difference. I have an application coming in that I will want to take care on this point.

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On Monday we are going to change the carrier frequency and see what happens.
I have also notice that the installers put the power supply cable of the part of the the feeding machine is located in the same cable tray as the fan cables. They are possible even touching at some points.

Could this have negative effect on noise and harmonics on supply cable?

Can some one with much more experience than i explain the difference in performance of a line reactor vs an emi filter? and why it is good to use both?

kallileo said:

Could this have negative effect on noise and harmonics on supply cable?

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Yes, especially over a long run. Segregate them. Did you check the earthing on the cable tray?

I didn't go to the farm but from what I heard from technician we sent there it seems that most of the components aren't grounded very well. The carrier frequency was already set to the lowest setting of 2 KHz.
The Delta inverter in use is from the most economical line and as stated in the manual the maximum cable length is just 20m and 50m using an output reactor.
For start Delta suggests installing ferrite rings and see what happens and then maybe a output reactor.
I don't have a good feeling about this. Probably we will have to replace the original drive with smaller that will located near the fans.