LEESON AC Motor Trouble Shooting-Guide - Manual

Motor Trouble-Shooting Chart
Caution:
1. Disconnect power to the motor before performing service or maintenance.
2. Discharge all capacitors before servicing motor.
3. Always keep hands and clothing away from moving parts.
4. Be sure required safety guards are in place before starting equipment.
Motor fails to start upon
initial installation.
Problem: What To Do: Like Causes:
Motor is miswired. Verify motor is wired correctly.
May be able to reassemble; otherwise, motor should be replaced. Motor damaged and rotor is striking stator.
Replace fan guard. Fan guard bent and contacting fan.
Motor has been running, then
fails to start. Fuse or circuit breaker tripped. Replace fuse or reset the breaker.
Stator is shorted or went to ground. Motor
will make a humming noise and the circuit
breaker or fuse will trip. Disassemble motor and inspect windings and internal connections.
A blown stator will show a burn mark. Motor must be replaced or
the stator rewound.
Capacitor (on single phase motor) may have
failed.
Inspect to see that the load is free. Verify amp draw of motor
versus nameplate rating.
Starting switch has failed.
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.
Motor runs but dies down. Voltage drop. If voltage is less than 10% of the motor’s rating contact power
company or check if some other equipment is taking power away
from the motor.
Verify the load has not changed. Verify equipment hasn’t got tighter. If
fan application verify the air flow hasn’t changed. Load increased.
Motor takes too long to accelerate. Defective capacitor Test capacitor per previous instructions.
Faulty stationary switch. Inspect switch contacts and connections. Verify that switch reeds
have some spring in them.
Bad bearings. Noisy or rough feeling bearings should be replaced.
Motor runs in the wrong direction. Incorrect wiring.
Make sure that the voltage is within 10% of the motor’s name-
plate rating. If not, contact power company or check if some other
equipment is taking power away from the motor.
Motor overload protector continually
trips. Load too high.
Rewire motor according to wiring schematic provided.
Motor overloaded or load jammed.
Voltage too low.
Ambient temperature too high.
Protector may be defective.
Winding shorted or grounded.
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.
Verify that the load is not jammed. If motor is a replacement,
verify that the rating is the same as the old motor. If previous
motor was a special design, a stock motor may not be able to
duplicate the performance. Remove the load from the motor and
inspect the amp draw of the motor unloaded. It should be less
than the full load rating stamped on the nameplate.
Verify that the motor is getting enough air for proper cooling. Most
motors are designed to run in an ambient temperature of less than
40°C. (Note: A properly operating motor may be hot to the touch.)
Replace the motor’s protector with a new one of the same rating.
Inspect stator for defects, or loose or cut wires that may cause it
to go to ground.