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On 08/22/2003 03:43 PM, Frohne, Vickie wrote:cut
> Edison was the DC guy, and his company actually did put generating
The last is nothing to be sneezed at; the big
circuit breakers at a substation are synchronous
so as to minimize the arc when they open. These
things are a highly amusing combination of cleverness
and brute force: they have a syncrhonous motor
that stays in phase with the current. The motor
drives a disk with a dog; the dog is normally
retracted, but when it comes time to trip the
breaker the dog sticks out and knocks out the
three bars that carry the current, bing, bing,
bing. A view looking down the axis is:
Z
O----
Y X
where the dog is about to whack the X phase. And
even so it takes lots of cleverness to extinguish
the bit of arc that occurs anyway.