48
6-2-4 Trouble Diagnosis
Table 35. Trouble diagnosis
Power source Contactor
Cause of trouble
Trouble
Mutual
relation
Phenomenon
Melting of power source fuse
Drop of power source voltage.
Power source voltage is too
high.
Operation of fuse-free breaker
Failure of sliding (moving)
part
Melting of contact
Adherence of tacky substances
to the contacting face of iron
Wear of the contacting face of
iron core
Damage of return spring
Defective contact Spring
Dust or rust on the contacting
face of iron core
Difective shading coil
Wire-breaking of coil
Rare short of coil
Adherence of oil to contact
Contactor does not close.
It can close, but cannot self-hold.
Contactor does not open and close.
Beats are produced.
Burn-out of coil
Melting of contact
Abnormal wear of contact
Short circuit between phases.
Thermal overload relay easily operates.
Thermal overload relay does not operate.
Fusing of thermal overload relay heater.
Contactor closes, but motor does not rotate.
Overheat of contact
How to read this Table:
Read the Table from the phenomenon
column at the left end toward the right,
and select the causes from the black
portion, then find the counter-
measures from the counter-
measures column below
the black portions.
Countermeasures
There is a case of phase failure. Investigate the
cause and replace the fuse with one with a correct
Investigate the capacity of power source, tap voltage
and thickness and length of wire. Consult with
power company, our company's agent, sales store,
and service station about the troubles.
Investigate the cause, remove it and again turn
on power.
Disassemble the contactor, remove foreign sub-
stances, or replace defective parts.
Replace parts around the contact. (fixed, moving
contacts and contact spring)
Clean the contacting face of iron core with cloth.
The mechanical endurance has reached its limit.
Replace iron core.
Replace parts. (return spring)
Replace parts. (contact spring)
Place the starter in dust-proof or anti-corrosion box.
Clean the contacting face of iron core with cloth.
Replace parts. (fixed and moving iron cores)
Replace parts. (coil)
Replace parts. (coil)
Clean it with cloth.
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