11
MOTOR TROUBLESHOOTING
This chart suggests common answers to electric motor problems. The information is not
all-inclusive and does not necessarily apply in all cases. When unusual operating conditions,
repetitive failures, or other problems occur, consult an electric motor service firm.
Symptom
Possible Cause(s)
Corrective Action
Motor fails to start
1. Blown fuses
1. Replace with time-delay fuses.
Check for grounded winding
2. Voltage too low at motor
terminals due to line drop
2. Consult local power company.
Increase wire size (refer to
Tables A & B). Check for poor
connections
3. Overload in motor starter tripped 3. Check and reset overload
relay in starter. Check heater
rating against motor nameplate
current rating
4. Overload (internal thermal
protector) tripped
4. Check motor load. If motor
has an automatic or manual
reset thermal protector, check
if tripped
5. Improper line connections
5. Check connections against
diagram supplied with motor
6. Motor may be overloaded
6. Reduce load or increase motor
size
Motor does not come up to
speed or takes too long to
accelerate
1. Not applied properly
1.
Consult motor service firm for
proper type. Use larger motor
2. Voltage too low at motor
terminals
2. Increase wire size (refer to
Tables A & B). Check for poor
connections. Check for voltage
unbalance (3-Phase)
3. Starting load to high
3. Check load motor is carrying at
the start
4. Excess loading; tight belts
4. Reduce load; increase motor
size. Adjust belts
