Symptoms and possible Causes

Possible remedy

I. Motor fails to start :

a)Power not connecteda)Connect power to motor.
b)Faulty (open) fusesb)Test/Replace Fuses.
c)Low voltagec)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 connectiond)Tighten connection.
Check the rotary switch terminals & strator contacts.
e)Overload control trippedd)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 motorf)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 stiffi)Use special lubricant for special conditions.
j)Over loadj)Reduce load, check fan wheel and clean.
k)Jamming of shoulder washer or cup washerk)Check for the wear in the parts and the mating parts and replace if necessary.
l)Jamming due to misalignment in assemblyl)Check for the proper alignment of fan-cover, gearhousing and front cover. Replace wornout parts.
m)Jamming of gearsm)Check for the damaged, wornout gears and traping of foreign materials. Remove and replace accordingly.

II. Motor Noisy :

a)Motor running single phasea)Stop motor, then try to start (it will not start in single phase). Check for open in one of the lines or circuits.
b)Vibrationb)Shaft assembly may be unbalanced. Remove the shaft assembly.
c)Air Gap not uniformc)Centre the rotor and if necessary replace bearings.
d)Noisy Ball bearingsd)Check, and replace bearings, if the noise is persistent and excessive.
e)Rotor rubbing on rotore)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 loada)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 ventilationc)Clean air passages and windings.
d)Incorrect voltage and frequencyd)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 loosea)Make sure end shields fit squarely and are properly tightened.
b)Bent Shaftb)Straighten the shaft or replace.
c)Excessive greasec)Remove excess grease.
d)Wrong grade of greased)Remove and replace with proper grease.
e)Insufficient greasee)Regrease bearings.
f)Foreign material in greasef)Flush bearings & relubricate. Make sure that grease supply is clean.
g)Bearing misalignedg)Align motor and check bearing housing. See that the bearing recess are exactly 90° with shaft.
h)Bearings damagedh)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 .