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Operation
Trouble Shooting
Between regular maintenance inspections, be
alert for signs of motor trouble.
symptoms are listed in the following table.
Correct any trouble immediately and AVOID
COSTLY REPAIR AND SHUT DOWN.
TROUBLE
Motor will not start.
Excessive hum.
Regular clicking.
Rapid knocking.
Vibration.
Vibration following motor
repair.
Motor overheating. (Check
with thermocouple or by
resistance method, do not
depend on touch).
Common
POSSIBLE CAUSES
Usually line trouble. Single phasing at starter.
Under Voltage.
Excessive Load.
High Voltage.
Unbalanced rotor.
Excessive wear of bearings.
Foreign matter in air gap.
Bad anti-friction bearing or dirt in lubricant.
Misalignment in coupling or flange.
Accumulation of dirt on fan.
Vibration in driven machine.
System natural frequency (Reed critical).
Twisted base or flange
Excessive end play.
Shaft bent or flange face runout.
Rotor out of balance; balance weights of fans
shifted on rotor.
Overload.
Single phase.
Dirt in motor.
Unbalanced voltage.
Rotor rubbing on stator.
Hazardous voltage.
Will cause death, serious injury,
electrocution or property damage.
Disconnect all power before working on
this equipment.
Check power source. DO NOT check with motor
energized! Check overloads, controls and fuses.
Check voltage and compare with nameplate rating.
Check voltage at motor terminals. Compare to
nameplate.
Disconnect motor from load to see if it starts without
load. Reduce load or replace motor with unit of
greater capacity.
Check input voltage. Check for proper connections.
Balance rotor.
Replace bearings. Check to determine cause of
wear and replace as necessary. Check alignment.
Remove foreign matter.
Replace bearing, clean wells and renew lubricant.
Realign motor and driven equipment.
Clean motor.
Run motor disconnected from driven load and check
for vibration. Eliminate source in driven equipment.
Alter rigidity of base structure.
Check flange alignment and shims.
Adjust end play.
Straighten or replace shaft. Reface or replace
housing.
Balance rotor.
Measure load and compare with nameplate rating.
Check for excessive friction in motor or complete
drive. Reduce load or replace motor with unit of
greater capacity.
Check current, all phases.
Check flow of air.
filters, if so equipped.
Check voltage, all phases.
Check air gap. Repair motor as necessary.
- 13 -
DANGER
CORRECTION
Check
Clean motor.
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