22
troubleshooting
Trouble
Cause
Remedy
Motor will not start
Power not available at motor
terminals
Check power at starter. Correct any bad connections between the
control apparatus and the motor.
Check starter contacts and control circuit. Reset overloads, close
contacts, reset tripped switches or replace failed control switches.
If power is not on all leads at starter, make sure overload and short
circuit devices are in proper condition.
Wrong connections
Check motor and control connections against wiring diagrams.
Low voltage
Check nameplate voltage against power supply. Check voltage at
motor terminals.
Open circuit in motor winding
Check stator windings for open circuits.
Fan drive stuck
Disconnect motor from load and check motor and Geareducer for
cause of problem.
Rotor defective
Look for broken bars or rings.
Unusual motor noise
Motor running single-phase
Stop motor and attempt to start it. Motor will not start if single phased.
Check wiring, controls and motor.
Motor leads connected incorrectly
Check motor connections against wiring diagram on motor.
Bad bearings
Check lubrication. Replace bad bearings.
Electrical unbalance
Check voltages and currents of all three lines. Correct if required.
Air gap not uniform
Check and correct bracket fits or bearing.
Rotor unbalance
Rebalance.
Cooling fan hitting end bell-guard
Reinstall or replace fan
Motor runs hot
Wrong voltage or unbalanced
voltage
Check voltage and current of all three lines against nameplate values.
Overload
Check fan blade pitch. See Fan User Manual. Check for drag in fan
drivetrain as from damaged bearings.
Wrong motor RPM
Check nameplate against power supply. Check RPM of motor and gear
ratio.
Bearings over greased
Remove grease reliefs. Run motor up to speed to purge excessive
grease. Does not apply to motors with sealed bearings.
Wrong lubrication in bearings
Change to proper lubricant. See motor manufacturer’s instructions.
One phase open
Stop motor and attempt to start it. Motor will not start if single phased.
Check wiring controls and motor
Poor ventilation
Clean motor and check ventilation openings. Allow ample ventilation
around motor.
Winding fault
Check with Ohmmeter.
Bent motor shaft
Straighten or replace shaft.
Insufficient grease
Remove plugs and regrease bearings. Does not apply to motors with
sealed bearings.
Too frequent starting or speed
changes
Limit cumulative acceleration time to a total of 30 seconds per hour.
Set on/off or speed change set-points farther apart. Consider installing
a Marley VFD for fine temperature control.
Deterioration of grease or foreign
material in grease
Flush bearings and relubricate. Does not apply to motors with sealed
bearings.
Bearings damaged
Replace bearings.
