Comments by "Scott Franco" (@scottfranco1962) on "Contactors: how we power the big stuff" video.

  1. Note: a big advantage of solid state/semiconductor relays is that they can switch an AC voltage at its zero point. That is, it can watch the line voltage reach zero in the cycle, and switch at the zero point, effectively breaking the circuit when there is no current whatsoever flowing.
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  2.  @jfbeam  Yea, semiconductors tend to fuse closed, unlike most circuit boards, which tend to fuse open, or, as you say, contacts, which tend to fuse closed. When I worked in ICs we had a failure analysis presentation that showed why, complete with photos. Silicon... well, it melts with enough current. It forms a nice runny, and very conductive, river of molten silicon for an instant. I imagine that is right before it forms a miniature explosion. You kids won't remember, but we used to have UV erasable EPROMs with little windows in them. If you plugged them in backwards, cause, you know, stupid, or on purpose, you got a nice little light show. This probably accounted for the fact that bad ones never got kept around. They were too much fun to plug in backwards.
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  3.  @TheBackyardChemist  Do tell. I know it changes the waveform around, but it still has a zero crossing?
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