Symptoms and possible Causes
Possible remedy
I. Motor fails to start :
a) | Power not connected | a) | Connect power to motor. |
b) | Faulty (open) fuses | b) | Test/Replace Fuses. |
c) | Low voltage | c) | Check motor name plate values with power supply. Also check voltage at Motor terminals with motor under load. Make sure wire size is adequate. |
d) | Loose terminal lead connection | d) | Tighten connection. Check the rotary switch terminals & strator contacts. |
e) | Overload control tripped | d) | Wait for overload relay to cool. Try starting again. If the motor still does not start, check all the causes as outlined in the following. |
f) | Jammed or faulty shaft or Tool holder, Jamming the motor | f) | Disconnect the shaft and then start the motor. If the motor starts satisfactorily, check the shaft and tool holder. |
g) | Open circuit in stator winding or Short circuit in stator winding or winding grounded. | g) | Check for open circuit or for shorted coil and test for grounded winding. |
h) | Bearing stiff and damaged. | h) | Free bearings or replace. |
i) | Grease too stiff | i) | Use special lubricant for special conditions. |
j) | Over load | j) | Reduce load, check fan wheel and clean. |
k) | Jamming of shoulder washer or cup washer | k) | Check for the wear in the parts and the mating parts and replace if necessary. |
l) | Jamming due to misalignment in assembly | l) | Check for the proper alignment of fan-cover, gearhousing and front cover. Replace wornout parts. |
m) | Jamming of gears | m) | Check for the damaged, wornout gears and traping of foreign materials. Remove and replace accordingly. |
II. Motor Noisy :
a) | Motor running single phase | a) | Stop motor, then try to start (it will not start in single phase). Check for open in one of the lines or circuits. |
b) | Vibration | b) | Shaft assembly may be unbalanced. Remove the shaft assembly. |
c) | Air Gap not uniform | c) | Centre the rotor and if necessary replace bearings. |
d) | Noisy Ball bearings | d) | Check, and replace bearings, if the noise is persistent and excessive. |
e) | Rotor rubbing on rotor | e) | Centre the rotor and replace bearings if necessary. |
f) | Object caught between fan and End shield or has damaged fan. | f) | Dismantle motor and clean or replace the damaged parts. |
g) | Shoulder washer/Cup Washer/lock washer working loose. | g) | Replace the worn out parts and fit them firmly. |
h) | Wornout or damaged gears or gearsshaft. | h) | Replace the damaged / wornout gear or shaft. |
III. Motor running temperature high :
a) | Over load | a) | Measure motor loading with ammeter, Reduce load. |
b) | Voltage imbalance in phases (fuse blown, faulty control) | b) | Check for voltage imbalance or single Phasing. Check for open in one of the lines or circuits. |
c) | Restricted ventilation | c) | Clean air passages and windings. |
d) | Incorrect voltage and frequency | d) | Check motor name plate value with power supply. |
e) | Motor stalled dur to 1) Faulty shaft 2) Faulty bearings 3) Other wornout parts like rotor shafts or washers | e) | Check and replace the faulty components. |
f) | Stator winding shorted or grounded or rubbing on rotor. | f) | Test windings for short circuit or grounding effect. |
IV. Bearing hot :
a) | End shields loose | a) | Make sure end shields fit squarely and are properly tightened. |
b) | Bent Shaft | b) | Straighten the shaft or replace. |
c) | Excessive grease | c) | Remove excess grease. |
d) | Wrong grade of grease | d) | Remove and replace with proper grease. |
e) | Insufficient grease | e) | Regrease bearings. |
f) | Foreign material in grease | f) | Flush bearings & relubricate. Make sure that grease supply is clean. |
g) | Bearing misaligned | g) | Align motor and check bearing housing. See that the bearing recess are exactly 90° with shaft. |
h) | Bearings damaged | h) | Replace bearings. |
V. General Precautions :
a) | Ensure that the supply connections and direction of rotation of the motor are correct. |
b) | Always connect the motor through a starter as per our recommendations. |
c) | Do not change the speed in multispeed geared motors while the motor is running. Change the speed only after stopping the motor . |