My craftsman 5.5HP air compressor keeps tripping the breaker when it cycles on. not every time, but 1 out of 3 or so. If it doesn't trip when it kicks on, it will be ok until the beginning of the next cycle.
It's on a 20A 115V circuit by itself. The 12GA run to the sub panel is only about 20' of wire. I've tried a different breaker, and it does the same thing. It's a tandem (two breakers on one 115V pole), but it did it with a regular breaker, too. The subpanel is Square D homeline. Nothing else gives me any problems, either at the subpanel or the main. I've even run my MIG welder off the same receptacle (not at the same time) and it didn't trip it.
Check the nameplate for fla (full load amps) You may have to run a larger line and a larger circuit breaker. 5.5hp is 4103 watts at over 30 amps. Not sure if that motor actually uses that, so check the name plate and size accordingly. Hope this helps.
Does this problem occur when the storage tank is empty? If it only occurs when there is pressure in the tank, it sounds like the "unloading" valve is not functioning correctly. This valve dumps the air from the compressor cylinders when the motor stops turning and makes the starting load much less. If the motor tries to start with pressure in the cylinders, I would expect it to trip the breaker. Don
If this compressor is "cord and plug" connected with an "OEM" cord, then it was designed to be "plugged in" to a receptacle. Maybe the bearings in the motor are about to fail, or the internal parts in the compressor are worn, and causing the motor to be overloaded. Are there any other loads on that circuit?