User`s manual

11
TROUBLESHOOTING
Electric Motor:
TROUBLE
CAUSE
WHAT TO DO
Motor Fails to Start
Blown Fuses
Replace fuses at least 125 % of nameplate amperes.
Improper current supply
Ensure the power supplied agrees with motor nameplate
and load factor.
Improper line connections
Check connections with diagram supplied with motor.
Open circuit in winding or
starting switch
Indicated by humming sound when switch is closed.
Repulsion induction motors may spark at brushes. Check
for loose wiring connections; also see if starting switch
inside motor is closed.
Mechanical failure
Ensure motor and drive turn freely. Check bearings and
lubrication.
Short circuited stator
Indicated by blown fuses. Motor must be rewound.
Motor may be overloaded
Reduce load.
Defective capacitor
Check for short circuit, grounded or open capacitor,
replace if necessary.
Motor Stalls
Overloaded motor
Reduce load.
Low motor voltage
See that nameplate voltage is maintained.
Open circuit
Fuses blown, check overload, relay, stator and reset-
buttons.
Motor runs and then
dies
Power failure
Check for loose connections to line, to fuses and to
control.
Motor does not
come up to speed
Open primary circuit
Locate fault with testing device and repair.
Motor takes too long
to accelerate
Excess loading
Reduce load.
Poor circuit
Check for high resistance.
Applied voltage too low
Get power company to increase power tap.
Wrong rotation
Wrong sequence of phases
Reverse connections at motor.
Motor overheats
while running under
load
Overload
Reduce load
Dirt build-up, insufficient
ventilation.
Clean
May have one phase open
Ensure all leads are well connected.
Unbalanced terminal voltage
Check for faulty leads, connections.
Shorted stator coil
Repair and then check wattmeter reading.
Faulty connection
Indicated by high resistance.
High voltage
Check terminals of motor with a voltmeter.
Low voltage
Check terminals of motor with voltmeter.
Motor vibrates after
corrections have
been made
Motor misaligned
Realign.
Weak foundations
Strengthen (tighten) base.
Scraping noise
Fan rubbing
Remove or clear interference.
Fan striking housing
insulation
Clear fan.
Noisy operation
Rotor or fan wheel unbalance
Rebalance.