ABB MT Série Notice Technique page 9

TROUBLE
Motor vibrates
Scraping noise
Noisy operation
Hot bearings general
Hot bearings ball
LV Motors/Machine Instructions 10-2000
CAUSE
Motor misaligned
Weak support
Coupling out of balance
Driven equipment unbalanced
Defective bearings
Bearings not in line
Balancing weights shifted
Contradiction between balancing of
rotor and coupling
(half key – full key)
Polyphase motor running single phase Check for open circuit.
Excessive end play
Fan rubbing fan cover
Fan striking insulation
Motor loose on bedplate
Airgap not uniform
Rotor unbalance
Bent or sprung shaft
Excessive belt pull
Pulleys too far away
Pulley diameter too small
Misalignment
Insufficient grease
Deterioration of grease or lubricant
contaminated
Excess lubricant
Overloaded bearing
Broken ball or rough races
WHAT TO DO
Realign.
Strengthen base.
Balance coupling.
Rebalance driven equipment.
Replace bearings.
Line up properly.
Rebalance motor.
Rebalance coupling or motor
Adjust bearing or add shim.
Remove interference.
Clear fan.
Tighten holding bolts.
Check and correct bracket fits or bearing.
Rebalance.
Straighten or replace shaft.
Decrease belt tension.
Move pulley closer to motor bearing.
Use larger pulleys.
Correct by realignment of drive.
Maintain proper quality of grease in bearing.
Remove old grease, wash bearings thoroughly in
kerosene and replace with new grease.
Reduce quantity of grease, bearing should not be
more than 1/2 filled.
Check alignment, side and end thrust.
Replace bearing, first clean housing thoroughly.
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