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 TM 5-683/NAVFAC MO-116/AFJMAN 32-1083
Table 5-2. Motor control trouble-shooting chart-continued.
CAUSE
REMEDY
3. Contacts weld shut or
freeze
Adjust, increasing pressure.
Replace if necessary.
Insufficient contact spring
pressure causing contacts to
burn and draw arc on closing.
Smooth surface or replace if
badly worn.
Very rough contact surface
causing current to be carried
by too small an area.
Use larger contactor or check
for grounds, shorts or
Abnormal inrush of current.
excessive motor load current.
Install larger device rated
for jogging service or caution
Rapid jogging.
operator.
Correct voltage condition.
Check momentary voltage dip
Low voltage preventing magnet
during starting.
from sealing.
Clean contacts with approved
solvent.
Foreign matter preventing
contacts from closing.
Remove short circuit fault and
check to be sure fuse or
Short circuit.
breaker size is correct.
4.
Contact Chatter
Replace.
Broken pole shader.
Improve contact or use holding
Poor contact in control
circuit interlock (3-wire
circuit.
control).
Correct voltage condition.
Check momentary voltage dip
Low voltage.
during starting.
5. Arc Lingers Across
Contacts
Check wiring diagram to see
If blowout is series, it may
kind of blowout.
be shorted.
Check wiring diagram through
If blowout is shunt, it may be
blowout.
open circuited.
See that arc box is on
Arc box might be left off or
contactor as it should be.
not in correct place.
Increasing travel of contacts
If no blowout used, note
increases rupturing capacity.
travel of contacts.
5-20
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