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Air compressor starts slowly and then trips 20 amp breaker.

The compressor turns freely by hand. Could this be caused by the start or run capacitor?

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  • fishingdaddy Dec 21, 2008

    It is a 4HP 110 Volt Craftman on it's own circuit with a new 20 amp breaker.

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Jsd

Posted on Mar 07, 2010

  • db990 Mar 07, 2010

    there is a valve which releases air pressure from the 'compressor' part of your unit when the motor stops. this avoids ther unit re-starting under load. if this is not operating properly the unit will struggle to get going and therefore the motor will draw too much current for too long causing the trip-out.

  • db990 Feb 11, 2011

    this won't help the original poster but, for anyone else reading, i have also found a bad capacitor or centrifugal switch on a single phase motor can cause this.
    the capacitor is a biggish can shaped object with a lead that connects to the motor windings either directly or through a centrifugal switch (if present). cost about 10 or 20 quid for a new one.
    the centrifugal switch is a switch (obviously) that will be found within the end casing of the motor. it disconnects the capacitor as the motor speed reaches a cetain level but maybe stuck open. may need cleaning/freeing up.

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Sounds like the oil is cold. Let all the air out and let it run for 3-4 minutes without building any pressure to warm the oil.

Posted on Jan 01, 2009

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Is it 220 or 110 ? How many horse power is it but most importantly is how many amps is the motor itself? If it is 15 amps let's say then that doesn't leave much more for anything else to be running on the same circuit of which you have the compressor plugged into. While 110 is more convenient, I know that is my preferred choice, when you get to 3 HP or over size motors your looking at close to or right at 15 amps of supply needed. Could also be the breaker needs replacing. Hope this helps.

Posted on Dec 20, 2008

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