Publication 2100-IN012C-EN-P - April 2009 93
Maintenance Chapter 9
10. Check locking or interlocking devices for proper working
condition.
11. Adjust, repair, or replace any device if necessary.
12. Check power contacts for excessive wear and dirt accumulation
and vacuum or wipe contacts with a soft cloth to remove dirt as
needed.
Contacts are not harmed by discoloration and slight pitting.
Contacts should never be filed, as this could reduce the life of
the contacts. Contact spray cleaners should not be used, as they
cause sticking on magnetic pole faces or in operating
mechanisms, interfering with the electrical continuity of the
contacts. Contacts should be replaced only after the silver has
become badly worn. Always replace contacts in complete sets to
avoid misalignment and uneven contact pressure.
13. Check for loose wire connections on power and control circuit
terminals.
Loose connections can cause overheating, hot spots, or arcing
faults that could lead to equipment malfunction or failure.
Replace any damaged parts or wiring.
14. Check contactor and relay coils for evidence of overheating,
such as cracking, melting, or burning of insulation.
If there is evidence of overheating, the coil must be replaced.
When replacing a coil, check and correct the overvoltage or
undervoltage conditions that may have caused the coil failure.
Be sure to clean any residue of melted coil insulation from other
parts of the device and replace as necessary.
15. Check all pilot lights and replace lamps and damaged lenses as
necessary.
16. Check all fuses.
If replacing fuses, install the same type and rated fuse that was
originally furnished with the MCC.
17. Remove accumulated dust and dirt from structure and individual
units by vacuuming.
Do not use compressed air, as it may contain moisture and blow
debris within the enclosure.
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