Quote:
Originally Posted by kamesama980
I'm not near industrial...ins't much of any industrial in town at all.
No ground rod. it's done through the water supply pipe.
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You're assuming that you aren't sharing a substation with a concern that either "regenerates" power back into the line or which uses some sort of system. You could also be the victim of circumstance, for example you're getting surges from natural sources like thunderstorms.
Three phase motors can generate noise but what really generates noise are power conversion systems that use switching, for example variable frequency drives. These can generate horrendous harmonics. There are established limits for the amount of harmonic distortion but sometimes machines do not always work properly.
Utilities do NOT like it when industrial customers use systems that put "dirty" power back into the lines. Really annoys the crap out of them.
To actually see these harmonics you need to monitor the power using an oscilloscope or a spectrum analyser.
Another possiblity is someone who is "putting power back into the grid". Such a person may be using an inverter to generate AC. The square waves that inverters generate are rich in harmonics, which is what gives them their square shape in the first place.
Quote:
Originally Posted by kamesama980
Where would I find the whole-house noise filter? That sounds most promising since the UPSs I use on the computer are basically noise filters with battery backup.
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A suitable "noise filter" would be a very large inductor. Inductors have a higher resistance the higher the frequency of the electricity.
Alternately an isolation transformer would reduce harmonics the same way an inductor could do. However to run your whole home through an isolation transformer we're talking some pretty righteous bucks.
Odds are that someone on your side of the substation could be doing some nasty stuff. Could also be caused by surges in the line from thunderstorms or other transient sources.
Gene