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Troubleshooting
Remedy
1. Check power at starter. Correct any bad connections be-
tween the control apparatus and the motor.
2. Check starter contacts and control circuit. Reset overloads,
close contacts, reset tripped switches, or replace failed
control switches.
3. If power is not on all leads at starter make sure overload and
short circuit devices are in proper condition.
Check motor and control connections against wiring diagrams.
Check nameplate voltage against power supply. Check voltage
at motor terminals.
Check stator windings for open circuits.
Disconnect motor from load and check motor and Geareducer
for cause of problem.
Look for broken bars or rings.
Stop motor and attempt to start it. Motor will not start if single-
phased. Check wiring, controls, and motor.
Check motor connections against wiring diagram on motor.
Check lubrication. Replace bad bearings.
Check voltages and currents of all three lines. Correct if re-
quired.
Check and correct bracket fits or bearing.
Rebalance.
Reinstall or replace fan.
Check voltage and current of all three lines against nameplate
values.
Check fan blade pitch. See Fan Service Manual. Check for
drag in fan drive train as from damaged bearings.
Check nameplate against power supply. Check RPM of motor
and gear ratio.
Remove grease reliefs. Run motor up to speed to purge exces-
sive grease.
If not poor machining, replace worn bearing.
Change to proper lubricant. See motor manufacturer’s instruc-
tions.
Stop motor and attempt to start it. Motor will not start if single-
phased. Check wiring, controls, and motor.
Clean motor and check ventilation openings. Allow ample venti-
lation around motor.
Check with Ohmmeter
Straighten or replace shaft.
Remove plugs and re-grease bearings.
Flush bearings and relubricate.
Replace bearings.
See Fan Service Manual for blade pitching instructions.
Check transformer and setting of taps. Use higher voltage on
transformer terminals or reduce loads. Increase wire size or
reduce inertia.
Look for cracks near the rings. A new rotor may be required.
Have motor service man check motor.
Trouble
Motor Will Not Start
Unusual Motor Noise
Motor Runs Hot
Motor Does Not Come Up
To Speed
Cause
Power not available at motor terminals
Wrong connections
Low voltage
Open circuit in motor winding
Motor or fan drive stuck
Rotor defective
Motor running single-phase
Motor leads connected incorrectly
Ball bearings
Electrical unbalance
Air gap not uniform
Rotor unbalance
Cooling fan hitting guard
Wrong voltage or unbalanced voltage
Overload
Wrong motor RPM
Bearings over-greased
Rotor rubs stator bore
Wrong lubricant in bearings
One phase open
Poor ventilation
Winding fault
Bent motor shaft
Insufficient grease
Deterioration of or foreign material in
grease
Bearings damaged
Incorrect fan blade pitch
Voltage too low at motor terminals be-
cause of line drop
Broken rotor bars