PROBLEM PROBABLE CAUSE
Motor Fails to Start Blown fuse or open circuit Replace fuse or reset circuit breaker
breaker
Overload trips Check and reset overload
Improper line connections Check connections with diagram supplied
with motor
Open circuit in winding or Check inside motor to determine if switch is closed.
starting switch. Evidence by Check for loose connections.
humming sound from motor
when switch is closed
Improper current supplied Check to determine that power supply agrees with
motor nameplate specifications.
Mechanical failure Determine that motor and drive turn freely. Check
bearings and lubrication
Short circuited stator Indicated by blown fuses. Motors must be rewound
Poor stator coil connection Remove end bells and locate with a test lamp.
Defective rotor Look for broken bars or end rings. Replace rotor
Motor overloaded Reduce load or replace unit with larger motor
With a 3 phase power source Check line for open phase
one phase may be open
Defective capacitor Replace capacitor
Motor Stalls Wrong application Change type or replace unit with a larger motor,
consult factory
Overloaded motor Reduce load or replace unit with a larger motor.
Low line voltage Check across AC line and correct if possible
Motor Runs and Then Partial loss of line voltage Check for loose connections. Determine adequacy
SOLUTION
TROUBLE SHOOTING GUIDES
ELECTRIC MOTORS
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