91Publication 2100-IN012C-EN-P - April 2009 91
Chapter
9
Maintenance
A periodic maintenance program should be established for MCCs to
avoid unnecessary downtime. The frequency of service to MCCs will
depend upon the equipment usage and the environment in which it
operates. The following is a suggested checklist and can be used to
establish a maintenance program.
Maintain the MCC
1. Inspect the MCCs once per year or per established maintenance
program.
2. Carefully inspect doors and enclosure sides for evidence of
excessive heat.
3. Check for moisture or any signs of dampness or drippings inside
the MCC.
a. Seal off conduit, cracks, and openings that have allowed
and/or could allow moisture to enter the MCC enclosure.
b. Dry or replace and clean insulating material that is damp or
wet or shows signs of moisture.
c. Check devices such as contactors, circuit breakers, disconnect
switches, relays, and push buttons for wetness or signs of
moisture, corrosion, or contamination.
d. Replace damaged or malfunctioning parts.
4. Check the integrity of bus splice connections.
Bus splices can be easily identified by the label located on the
interior of the vertical wireway door or on the interior right-hand
side plate of frame mounted units. Recommended torque values
ATTENTION
De-energize the MCC before servicing.
IMPORTANT
Condensation in conduit or dripping from an outside
source is a common cause of MCC failure. Eliminate any
source of moisture.
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