VFD causes static on intercom.

[Al Crandall]

I wired up my new toy yesterday and the VFD causes so much static in the intercom between the house and my unattached shop that the intercom is unuasble. The static appears only when the motor is running. The higher the rpm, the louder the static. I have plugged the intercom into outlets on four different circuits thinking that the problem might be on just one leg of the 230v service and not on the other. No joy. The other VFD in my shop does not affect the intercom in any way. Any suggestions? Thanks, Al.

[Bill Grumbine]

Hi Al

I don't know that I have anything to offer, except to say that my VFD plays Old Harry with the AM radio. I can't listen to my favorite talk radio guys if I am turning. Fortunately, it only affects the shop and not the house, or cars going by (we tested that out). It does not affect our Radio Shack walkie talkies, which are not dependent on the electrical system to send their signal. Failing any results on quieting the VFD, you might be able to go to a different method of communication.

Bill

[Richard Allen]

Hi Al

When I ordered my Oneway I had the RFI (Radio Frequency Interference) filter added to the order. That was nearly $40.

http://www.oneway.on.ca/Oneway/images/lathe_accessories/RFI-Filter.jpg

They claim it can be instailed after you get your lathe so the instail should be simple.

The walkie talkies Bill is talking about most likely use FM for their carier and as such are not susptable to the kind of interference produced by the VFD.

You could contact the manufature of your VFD and get the particulars for putting in a RFI filter.

Thanks

Richard

[Russ Filtz]

If it's not RFI but interference going back up the power line, you can try putting a ferrite core around the plug end of what the VFD is connected to. Should be able to find these at Rat Shack.