air compressor

I have a 6 hp/110 compressor that runs off a dedicated 20 amp circuit. Lately the breaker won't hold and trips every time the compressor kicks on. I put a new breaker in but no luck. If I reset the breaker it works until the next time it kicks on.

The compressor is only a year old and has worked fine up until now. Any thoughts?

 

We need more information.

The new compressors are not rated normally. We will need the information off the motor tag on the compressor to size the breaker.

If this was a real 6hp compressor running on 110v it would draw about 60 amps :jd:

At 20 amps it is around a 1 hp motor. My guess would be that it is starting harder than when it was new and that is why it is tripping the breaker.

If at all possible I would look to see if you can hook it up 220v and run some number 10 wire to it.

Good luck and let us know
Mike

 

I assume you've been running it off this circuit for a long time with no problem? Try some of these things after you are sure there is enough current available to start it. I see this daily, several times.


1) Single-phase motors have a mechanical switch resembling the points in a distributor just inside the rear of them , if they become stuck together, the motor will keep the much-higher-torque start windings in the circuit longer than it should. The contacts can be filed clean the same way as points, or the switch is probably available at your local motor shop if the damage is excessive.
2) There are 1, maybe 2 large capacitors mounted to the motor, the motor shop can test these (usually free of charge) if you don't have a meter to read capacitance. These are imperitive to the motor's function and should be in tolerance- within 10%.
3) There must be a valve somewhere between the compressor head and the storage tank, it holds pressure off the head so the motor isn't trying to move the compressor under a terrible load when it starts up. Try bleeding all the air entirely out of the tank and starting it to see if this is the case.
4) Breakers do go bad, try another circuit, or use a clamp style ammeter to see if the motor really is drawing an excess of current, it should be 2-3 times the nameplate current when it starts up( about a second or so in a healthy motor. And then 1/3-1/2 nameplate current with the belt off (no load).
Good luck, Tom