Teco Installation and Maintenance Manual
TEFC Squirrel Cage Induction Motors
Teco Electric and Machinery Company
Manual Number: IOM ~ TEFC Rev.01
25
ii.
Deformation of shaft.
iii.
Loose parts or couplings.
5.5.
NOISE.
5.5.1. Points to Note.
Not all noise is the result of a fault or abnormality. For instance, wind and
slight electromagnetic sounds are perfectly normal. They will remain at the
same level no matter how long the motor is in operation. Generally the
louder the noise, the larger the vibration amplitude will be.
5.5.2. Bearing Sound.
i.
Bearing noise is a guide to the condition of the motor bearings
without dismantling the motor.
ii.
Normal bearing sound in general is continuous, not intermittent. The
sound may tend to increase with the age of the bearings, but its
increase is gradual and hardly noticeable by the ear.
iii.
Abnormal bearing sound is intermittent, rarely continuous.
iv.
Some motors will emit noise when unloaded or after greasing due to
skating. This is normal and temporary.
5.5.3. Abnormal bearing sound generally develops from the following causes:
i.
Foreign matter in grease.
ii.
Scratches on the contact surface of the bearing.
iii.
Rust on the contact surfaces of the bearing due to moisture ingress.
iv.
Poor quality of grease or wrong type of grease.
v.
Insufficient grease (the sound could be continuous).
5.5.4. Causes of abnormal electromagnetic sound:
i.
Single phasing.
ii.
Short circuit in windings.
iii.
Unbalanced air gap resulted from serious bearing wear.
