User Manual

39
ELECTRIC MOTOR TROUBLESHOOTING GUIDE
PROBLEM POSSIBLE CAUSES REMEDY
Overload Relays Slow Starting (10- 15 seconds Reduce starting load. Increase
Tripping Upon Starting or more) due to High Inertia motor size if necessary.
Load
Low voltage at motor Improve power supply and/or
terminals. increase line size.
Running Loaded Overload. Reduce load or increase motor
size
Unbalanced Input Current. Balance supply voltage
Single Phasing Eliminate
Excessive Voltage Drop Eliminate (see above).
Too frequent starting or Reduce frequency of starts
intermittent overloading. and overloading or increase
motor size.
High Ambient Starter Reduce ambient temperature
Temperatures or provide outside source of
cooler air.
Wrong Size Relays Correct size per nameplate
current of motor. Relays have
built in allowances for service
factor current. Refer to
National Electrical Code.
Excessive Vibration Out of Balance:
(mechanical) a. Motor mounting Be sure motor mounting is
tight and solid.
b. Load. Disconnect belt or coupling -
restart motor -if vibration
stops, the unbalance was in
load.
c. Sheaves or coupling Remove sheave or coupling -
securely tape 1/2 key in shaft
keyway and restart motor -if
vibration stops, the unbalance
was in the sheave or coupling.
d. Motor If the vibration does not stop
after checking a, band c
above, the unbalance is in the
motor -replace the motor.
e. Misalignment on Close Check and realign motor to the
Coupled Application. driven machine.