You may want to look into a small contactor rather than a simple relay. The
start up current and the
resulting sparks can burn out simple relays. The contactors lugs are amp rated.
: Hi folks...
: Finally scored the Big Dust Collector (Oneida 3 hp), and am in the process
: of getting it hooked up. I was planning (OK, Hoping) to put microswitches at
: the blast gates so I can turn the unit on/off by opening and closing the
: gates. Everything went fine in the planning phase, then when I actually
: started getting ready to put stuff together, I realized I had no idea how to
: build the rely....
: Here's the stats:
: # HP motor, 220V, 20 Amp (at least that's the circuit breaker it wants).
: I was hoping to use some simple low voltage DC for the switching - pretty
: much whatever low cost transformer I can find at Rat Shack, and switches to
: go with it.
: I'm assuming that I just wire the whole thing up so that I've got the
: 220 feed going into the relay, the plug from the DC goes into the relay, and
: the low voltage on/off controls the relay (DC current = on, no current : off). SO here's the big question: how do I figure out what size/type of
: relay I need? I've dug through all of my old (really old) electronic
: textbooks, and found lots of theory, but nothing of real practical value. I
: dug through all of my industrial catalogues, and discovered that there are
: way more types of relays than I ever imagined. I searched the web, and got
: buried (no surprise there...).... So, having pretty much exhausted what my
: little brain could come up with, I figured I'd query the collective brain
: out there......
: Thanks to everyone.....
: __James J.B.N. DuPrie