Ground loops

[bthielen]

Re: Ground loops

This is interesting. Since I started this discussion two days ago, we have been dealling with an issue on one of our products in operation for over two years. The machine wouldn't function correctly and after many hours of monitoring voltage levels with VOMs and O-scopes, have discovered an electrical noise problem that was causing encoder and photoelectric sensor malfunctions. We have not yet isolated the source but have managed to isolate the components and their wires to allow the machine to function normally. Strange coincidence.

Bob

 

[brian john]

Re: Ground loops

Don:
Two of the issues we see regularly are with AV systems, hum bars in the displays or noticeable hum in the audio system. The second issue we run across is "screen shake". Both of these issues can be related to neutral ground issues. Generally we find accidental or intentiional downstream grounded neutrals. There are other causes of "screen shake", such as equipment or electric room location and of course bad video cards in PC's.

 

[karl riley]

Re: Ground loops

Brian, my experience is the same. When it is proximity to the electric room the usual suggestion is to shield (expensive). But if some of the cables in the electric room have net current, this part of the field is unaffected by shielding. For this reason the net currents due to incorrect neutral connections (usually to ground) have to be eliminated before the feasibility of shielding can be decided on.
Do you ever work with shielding companies?

Karl