ABB MT Série Manuel D'installation, D'exploitation Et De Maintenance page 20

TROUBLE CAUSE
Motor takes too Excessive load
long to accelerate
Low voltage during start
and/or draws high
current
Defective squirrel cage rotor
Applied voltage too low
Wrong rotation Wrong sequence of phases
direction
Motor overheats Overload
while running
Frame or ventilation openings may be
full of dirt and prevent proper ventilation
of motor
Motor may have one phase open
Grounded coil
Unbalanced terminal voltage
Motor vibrates 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)
Poly phase motor running single phase
Excessive end play
Scraping noise Fan rubbing end shield or fan cover
Loose on bedplate
Noisy operation Air gap not uniform
Rotor unbalance
Hot bearings Bent or sprung shaft
Excessive belt pull
Pulleys too far away from shaft
shoulder
Pulley diameter too small
Misalignment
Insufficient grease
Deterioration of grease or lubricant
contaminated
Excess lubricant
Overloaded bearing
Broken ball or rough races
20
ABB Motors and Generators | Low voltage motors manual, 3GZF500730-85 Rev F 02-2015
Standard_Manual_LV_Motors_ML_revF_Book.indb 20
WHAT TO DO
Reduce load.
Check for high resistance. Make sure that an adequate cable size
is used.
Replace with new rotor.
Correct power supply.
Reverse connections at motor or at switchboard.
Reduce load.
Open vent holes and check for a continuous stream of air
from the motor.
Check to make sure that all leads and cables are well connected.
Motor must be rewound.
Check for faulty leads, connections and transformers.
Realign.
Strengthen base.
Balance coupling.
Rebalance driven equipment.
Replace bearings.
Repair motor
Rebalance rotor.
Rebalance coupling or rotor.
Check for open circuit.
Adjust bearing or add shim.
Correct fan mounting.
Tighten holding bolts.
Check and correct end shield fits or bearing fits.
Rebalance rotor.
Straighten or replace shaft.
Decrease belt tension.
Move pulley closer to motor bearing.
Use larger pulleys.
Correct by realignment of the drive.
Maintain proper quality and amount 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 half full.
Check alignment, side and end thrust.
Replace bearing, clean housing thoroughly first.
6/2/2015 6:44:26 PM