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10. TROUBLESHOOTING CHART X SOLUTIONS
This troubleshooting chart provides a basic list of problems that may occur during motor operation, possible
causes and recommended corrective actions. In case of doubts, please contact WEG Service Center.
Problem
Motor does not start, neither coupled nor
decoupled
The motor starts at no-load, but fails when
load is applied. It starts very slowly and
does not reach the rated speed.
Abnormal / excessive noise
Motor overheating
Bearing overheating
120
Manual of Electric Motors
Possible cause
Power cables are interrupted.
Blown fuses.
Wrong motor connection.
Locked rotor.
Load toque is too high during start-up.
Too high voltage drop in the power cables
Defective transmission component or
defective driven machine.
Misaligned / unleveled base.
Unbalanced components or unbalanced
driven machine
Different balancing methods used for motor
and coupling balancing (halve key, full key)
Wrong motor direction of rotation
Loose bolts
Foundation resonance
Damaged bearings
Insufficient cooling
Overload
Number of starts per hour is too high or the
load inertia moment is too high
Power supply voltage too high
Power supply voltage too low
Interrupted power supply
Voltage unbalance at the motor terminals
Direction of rotation is not compatible with
the unidirectional fan
Excessive grease / oil
Grease / oil aging
The used grease / oil does not matches the
specified one
Lack of grease / oil
Excessive axial or radial forces due to
the belt tension
Corrective action
Check the control panel and the motor
power supply cables.
Replace blown fuses.
Correct the motor connection according to
connection diagram.
Check motor shaft to ensure that it rotates
freely.
Do not start the motor on load.
Check the installation dimensioning
(transformer, cable cross section, relays,
circuit breakers, etc.)
Check the transmission force, the coupling
and the alignment.
Align / level the motor with the driven
machine
Balance the machine set again
Balance the motor again
Reverse the direction of rotation
Retighten the bolts
Check the foundation design
Replace the bearings
Clean air inlet and outlet and cooling fins
Check the minimum required distance
between the fan cover and nearest walls.
See item 7
Check air temperature at inlet
Measure motor current, evaluate motor
application and if required, reduce the load
Reduce the number of starts per hour
Check the motor power supply voltage.
Power supply voltage must not exceed the
tolerance specified in item 7.2
Check the motor power supply voltage and
the voltage drop. Power supply voltage
must not exceed the tolerance specified in
item 7.2
Check the connection of the power cables
Check for blown fuses, wrong commands,
voltage unbalance in the power line, phase
fault or interrupted power cables
Check if the direction of rotation matches
the rotation arrow indicated on end shield
Clean the bearing and lubricate it
according to the provided
recommendations
Lubricate the bearing according to the
provided recommendations
Reduce the belt tension
Reduce the load applied to the motor