Reply by Tennessee

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Posted on Do I need a new start capacitor?

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2873 posts in 2514 days

#1 posted 11-06-2012 04:12 PM

You can tell if it is the capacitor if you hear a humming noise in the motor just before the breaker trips, but the motor is not really turning.
Caps are designed to give the magnetic field a push in one direction, and are wired to give a large inrush of one half of an AC sine wave voltage over and over to get the rotor moving. In a lot of capacitor start, induction run motors, the capacitor is used for the first 75% of run-up rotation, and then the switch changes the motor over to standard induction run, taking the cap and it’s start windings out of the circuit.

My guess is either you have a weakening start winding which would raise the inrush amperage, or your breaker is weakening.
Do NOT upgrade the size of the breaker. It is probably sized correctly, after all these years of working well.
Changing the cap may help a little, but I doubt it. Also, if your motor has an internal switch, dirty contacts can raise the amerage, as well as stiff bearings and overall general load bearings. Just do not put in a bigger breaker. Worst case, bad windings, causing you to lose the motor. Best case, weakening breaker. In the middle, bad bearings and machine load.

-- Tsunami Guitars and Custom Woodworking, Cleveland, TN

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