Re: How much DC on your mains ?
I was called to a problem with intermittent AC motor control in Kent. The problem was only present for short periods, so it involved sitting drinking coffee with an eye on the scope. Eventually the culprit showed itself. At the peak of one half-cycle, a surprisingly large chunk was being taken out of the mains (around 20% for around 5 m.s.) This was causing the triac controller to go mad. The culprit was traced to a plating organisation on the same industrial estate. It would not take much treatment of this sort to result in an asymmetric waveform having an apparent DC value.
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