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.
EN-20
ABB Motors and Generators |
Low voltage motor manual 01-2009
