Re: motor starting relay


"Maxwell" <luv2fly99@xxxxxxx> wrote in message
news:s9Nuh.4275$uK1.857@xxxxxxxxxxxxxxx

I have a 230 volt, single phase, 5 hp motor on an air compressor. Not long
ago the capacitor starting switches failed, and I was unable to find new
ones. I did however find a couple of used ones to get going again
temporarly.

What I would like to do is replace the centrifical/mechanical switches
with a timed relay, but I'm not sure how to size the relay. The motor
draws 23 full load amps, but I'm just swiching the capacitor start
circuit. What's minumum rating I should consider when I look for a relay?

Use a contactor - maybe 50 Amps? You can parallel up the contacts for more
capacity if you use a smaller model. Relays aren't a good choice here.

One older method was to measure the current drawn by the motor and switch
out the start winding when it dropped enough, however that is tricky to do.
The timer should be OK - about 5 seconds so a 1 - 10 second adjustable timer
should work.

That's a honking big motor for single phase!

--
..
..
..
..
..
..
..
..



.

Relevant Pages

  • Re: TEAM-EM Tech Q GTB Fast Draw
    ... they say check motor swtiches possibly on the Ax relay - ...  I realize this probably means all motor switches in all stacks. ... the score motor switches are not the issue. ...
    (rec.games.pinball)
  • Re: SPDT remote controlled switch?
    ... One relay switches power ... ON and OFF and the other relay selects the motor or motor winding (drape ... I have drapes that have separate forward/reverse motors, ...
    (comp.home.automation)
  • Re: TEAM-EM Tech Q GTB Fast Draw
    ... they say check motor swtiches possibly on the Ax relay - ...  I realize this probably means all motor switches in all stacks. ... the score motor switches are not the issue. ...
    (rec.games.pinball)
  • Re: motor starting relay
    ... long ago the capacitor starting switches failed, and I was unable to find ... What I would like to do is replace the centrifical/mechanical switches ... with a timed relay, but I'm not sure how to size the relay. ... One older method was to measure the current drawn by the motor and switch ...
    (sci.electronics.misc)
  • Re: SPDT remote controlled switch?
    ... One relay switches power ... ON and OFF and the other relay selects the motor or motor winding (drape ... Even if both relays energize, only one motor ...
    (comp.home.automation)
Loading