TROUBLE CAUSE WHAT TO DO
Motor takes too long to
accelerate and/or draws
high current
Excessive load Reduce load.
Low voltage during start Check for high resistance. Make sure that adequate cable
size is used.
Defective squirrel cage rotor Replace with new rotor.
Applied voltage too low Correct power supply.
Wrong rotation direction Wrong sequence of phases Reverse connections at motor or at switchboard.
Motor overheats while
running
Overload Reduce load.
Frame or ventilation openings may
be full of dirt and prevent proper
ventilation of motor
Open vent holes and check for a continuous stream of air
from the motor.
Motor may have one phase open Check to make sure that all leads are well connected.
Grounded coil Motor must be rewound
Unbalanced terminal voltage Check for faulty leads, connections and transformers.
Motor vibrates Motor misaligned Realign.
Weak support Strengthen base.
Coupling out of balance Balance coupling.
Driven equipment unbalanced Rebalance driven equipment.
Defective bearings Replace bearings.
Bearings not in line Repair motor.
Balancing weights shifted Rebalance motor.
Contradiction between balancing of
rotor and coupling (half key - full key)
Rebalance coupling or motor.
Polyphase motor running single phase Check for open circuit.
Excessive end play Adjust bearing or add shim.
Scraping noise Fan rubbing end shield or fan cover Correct fan mounting.
Loose on bedplate Tighten holding bolts.
Noisy operation Air gap not uniform Check and correct end shield fits or bearing fits.
Rotor unbalance Rebalance rotor.
Hot bearings Bent or sprung shaft Straighten or replace shaft.
Excessive belt pull Decrease belt tension.
Pulleys too far away from shaft shoulder Move pulley closer to motor bearing.
Pulley diameter too small Use larger pulleys.
Misalignment Correct by realignment of the drive.
Insufficient grease Maintain proper quality and amount of grease in bearing.
Deterioration of grease or lubricant
contaminated
Remove old grease, wash bearings thoroughly in kerosene
and replace with new grease.
Excess lubricant Reduce quantity of grease, bearing should not be more than
half full.
Overloaded bearing Check alignment, side and end thrust.
Broken ball or rough races Replace bearing, clean housing thoroughly first.
Low voltage motor manual 01-2009 | ABB Motors and Generators EN – 41
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