Restarting a Compressor

by Nick
(Suffolk, Virginia)

I just recently received an old used air compressor from a friend.

It continues to cut off and trip the motor after a minute or so of running. It starts off fine but gradually slows to a halt.

I check the motor by disconnecting the belt drive to the compressor and it ran fine. I ran it for five minutes with no problems.

When running the compressor once the motor cools off I can reset it and it will do the same thing over again. When I received it, it was set to 220, but I converted it to 110, the motor is rated for both applications, I'm not sure if that could be a problem.




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Restarting a Compressor

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Jan 18, 2008
 Air Compressor Starting
by: Jim G

Sounds like you have no off on pressure switch in with the compressor to turn the unit on below a certain pressure and off when you are above your cut out or high pressure.

This pressure switch also dumps the sensing air for the next cycle.

Don't forget one 110 circuit is only good for 15 amps or around 1/2 HP rated motor.
Jan 15, 2008
 Restarting a Compressor
by: Bill - Publisher

Nick, congrats on getting the used compressor from your friend. Reading between the lines of your note may explain why your friend didn't want it anymore! ;-}

I'm a bit confused about the problem.

You say "It continues to cut off and trip the motor after a minute or so of running" and then go on to say "It starts off fine but gradually slows to a halt". Which? Does it stop abruptly or the motor slows down and then stops?

Not being a compressor mechanic, I'm guessing that the problem may be the motor itself. It may need re-brushing / rebuilding.

Since the motor is running hot under load, it may be going off on thermal overload, and it the thermocouple or heat sensing device won't allow it to start again until the motor cools.

Wish I could be more help, but it's really hard to diagnose electromechanical compressor problems from afar, and particularly when I normally just use 'em, I don't fix them.

You may want to Google "electric motor problem" as I did. You'll find a lot of advice about motor problems and resolutions, and maybe you can determine from those sites if it's your motor for sure.

Good luck.

Bill

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