On Thu, 28 Jul 2005 20:24:26 GMT, Ignoramus9394
wrote:



Thanks. I have become convinced that I need such a relay. What I would
like to find, for not too much money, is a relay with start/stop
buttons and overload protection for a 10 HP motor.

What is the proper name of such a thing and where should I look for
it. It is very painful to explain what I need, without knowing the
proper name for it.

Motor controller and you'd better find one used. New ones are big
bucks in that size.

It's possible to use the contactor you have now with the addition of
a few things to make a motor controller. I'd forgotten the fact that
you have a 3 pole contactor and you're only controlling the single
phase input so you can use that contactor with a pair of push button
momentary switches (one normally closed and the other normally open).
I happen to know that McMaster Carr sells a switch like this already
in a case for around $40 (we just got through putting one like it on a
friends new to him Logan lathe which is being powered by a VFD). But
these kind of push button start/stop switches are used on a lot of
equipment and should be easy to find if you look.

The tricky part is the overload protection. There are electronic
overload sensors out there that can be added to a setup like this.
However I'm not sure that I've ever seen any that aren't 3 phase. You
won't be able to use the 3 phase version since one of the things they
check for is all 3 phases loaded evenly. Drop one phase and they kick
out. If you can find a single phase version of these then you're set.
I have my doubts you'll ever find one used since they're a relatively
recent innovation in motor controls. I've not seen to many coming out
of used equipment yet.