Motor Trouble-Shooting (2)

Motor has been running, then fails to start.

Like Causes:
1. Fuse or circuit breaker tripped.
2. Stator is shorted or went to ground. Motor will make a humming noise and the circuit breaker or fuse will trip
3. Motor overloaded or load jammed.
4. Capacitor (on single phase motor) may have failed.
5. Starting switch has failed.

What To Do:
1. Replace fuse or reset the breaker.
2. Disassemble motor and inspect windings and internal connections. A blown stator will show a burn mark. Motor must be replaced or the stator rewound.
3. Inspect to see that the load is free. Verify amp draw of motor versus nameplate rating.
4. First discharge capacitor. To check capacitor, set volt-ohm meter to RX100 scale and touch its probes to capacitor terminals. If capacitor is OK, needle will jump to zero ohms, and drift back to high. Steady zero ohms indicates a short circuit; steady high ohms indicates an open circuit.
5. Disassemble motor and inspect both the centrifugal and stationary switches. The weights of the centrifugal switch should move in and out freely. Make sure that the switch is not loose on the shaft. Inspect contacts and connections on the stationary switch. Replace switch if the contacts are burned or pitted.


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