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 TM 5-683/NAVFAC MO-116/AFJMAN 32-1083
Table 4-3. AC induction motor trouble-shooting--continued.
Maintenance
Probable Cause
Trouble
Make sure bearings are properly
Friction high
Motor will
not
start
lubricated.
(cont 'd)
Check bearing tightness.
Check belt tension.
Check load friction.
check alignment.
contactor
Be sure field-applying
Field excited.
is open and field-discharge
contractor is closed through
discharge resistance.
Remove part of load
Load too great.
Check
power
S u p p lY
to solenoid.
Automatic field relay
not working.
Check
contractor tips.
Check
connections.
Reverse any two main leads of 3-
Wrong direction of
phase motor.
rotation.
reverse starting
Single-phase,
winding leads.
Decrease the load.
Motor will not come
Excessive load.
up to speed.
Check operation of unloading
device (if any) on driven machine.
Increase
voltage.
Low voltage.
contactor
Be sure field-applying
Field excited.
is open, and field-discharge
contactor is closed through
discharge resistance.
Check circuit connections. Be
No field exc itation.
Fails
to
pull
into
sure field applying contactor is
step.
operating.
Check for open circuit in field or
Check exciter output.
Check rheostat.
Set rheostat to give rated field
current when field is applied.
Check contacts of s witches.
4-30
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