Symptoms and possible Causes |
Possible remedy |
| I. Motor fails to start : |
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| 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. |
|
| 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. |
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| 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. |
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| 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 . |