Maintenance & Troubleshooting 3
−
3
MN427
Table 3-2
Troubleshooting Chart
Symptom
Possible Causes
Possible Solutions
Motor will not start
Usually caused by line trouble, such
as, single phasing at the starter.
Check source of power. Check overloads, fuses,
controls, etc.
Excessive humming
High Voltage.
Check input line connections.
Eccentric air gap.
Have motor serviced at local Baldor service center.
Motor Over Heating
Overload. Compare actual amps
(measured) with nameplate rating.
Locate and remove source of excessive friction in
motor or load.
Reduce load or replace with motor of greater capacity.
Single Phasing.
Check current at all phases (should be approximately
equal) to isolate and correct the problem.
Unbalanced voltage.
Check voltage at all phases (should be approximately
equal) to isolate and correct the problem.
Rotor rubbing on stator.
Check air gap clearance and bearings.
Tighten “Thru Bolts”.
Over voltage or under voltage.
Check input voltage at each phase to motor.
Open stator winding.
Check stator resistance at all three phases for
balance.
Grounded winding.
Perform dielectric test and repair as required.
Improper connections.
Inspect all electrical connections for proper
termination, clearance, mechanical strength and
electrical continuity. Refer to motor lead connection
diagram.
Bearing Over Heating Misalignment.
Check and align motor and driven equipment.
Excessive end thrust.
Reduce the end thrust from driven machine.
Insufficient grease in bearing.
Add grease until cavity is approximately
3
/
4
filled.
Dirt in bearing.
Clean bearing cavity and bearing. Repack with correct
grease until cavity is approximately
3
/
4
filled.
Vibration
Misalignment.
Check and align motor and driven equipment.
Rubbing between rotating parts and
stationary parts.
Isolate and eliminate cause of rubbing.
Rotor out of balance.
Have rotor balance checked are repaired at your
Baldor Service Center.
Resonance.
Tune system or contact your Baldor Service Center
for assistance.
Noise
Foreign material in air gap or
ventilation openings.
Remove rotor and foreign material. Reinstall rotor.
Check insulation integrity. Clean ventilation openings.
Growling or whining
Bad bearing.
Replace bearing. Clean all grease from cavity and
new bearing. Repack with correct grease until cavity
is approximately
3
/
4
filled.
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