Re: [CAD_CAM_EDM_DRO] Spindle Relay Question

In a message dated 5/25/2005 8:07:08 P.M. Central Daylight Time,
volitan@... writes:

Does a DPDT DC relay with that rating exist, or do I need a different
circuit altogether?<<

I never heard of a DPDT SSR. I once put six AC SSR's in "one box" for
on/off and reverse of a 3-phase Bridgeport, and it worked for a day or so, then
one set went open. I replaced the "bad one", and it worked again, but for no
more than a day. I had wired this sensibly so that it was impossible for
"both sides" to go on at once (would be a dead-short across the incoming lines),
but somehow "noise" or whatever would trigger the "off ones" when the "on
ones" were selected. I finally gave up and now use three SSR's only to switch
the three phases, and use a mechanical DPDT lever-switch to select direction
BEFORE turn-on.

With that experience, I suspect it might be very, very difficult to wire two
pairs of DC SSR's so that only one pair at a time could be switched on for
one of two directions. One would THINK so "on paper", but there seems to be
them thar lektrikul gremlins in thar! Jan Rowland




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