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E-12
Preventative Maintenance Schedule
General Notes (cont.)
7000A-UM151E-EN-P - October 2018
Contamination
If inspection reveals that dust, dirt, moisture or other contamination has
reached the control equipment, the cause must be eliminated. This could
indicate unsealed enclosure openings (conduit or other) or incorrect
operating procedures. Replace any damaged or embrittled seals and repair
or replace any other damaged or malfunctioning parts (e.g., hinges,
fasteners, etc.). Dirty, wet or contaminated control devices must be replaced
unless they can be cleaned effectively by vacuuming or wiping. Compressed
air is not recommended for cleaning because it may displace dirt, dust, or
debris into other parts or equipment, or damage delicate parts.
High Voltage Testing
High voltage insulation resistance (IR) or dielectric withstanding voltage
(megger) tests should not be used to check solid-state control equipment.
When meggering electrical equipment, such as transformers or motors,
solid-state devices must be bypassed before performing the test. Even
though no damage may be readily apparent after a megger test, the solid-
state devices are degraded and repeated application of high voltage can lead
to failure.
Maintenance after a Fault Condition
Opening of the short circuit protective device (such as fuses or circuit
breakers) in a properly coordinated motor branch circuit is an indication of a
fault condition in excess of operating overload. Such conditions can cause
damage to medium voltage motor control equipment. Before restoring
power, the fault condition must be corrected and any necessary repairs or
replacements must be made to restore the medium voltage motor control
equipment to good working order. Refer to NEMA Standards Publication
No. ICS-2, Part ICS2-302 for procedures. Use only replacement parts and
devices recommended by Allen-Bradley to maintain the integrity of the
equipment. Ensure the parts are properly matched to the model, series and
revision level of the equipment. After maintenance or repair of the
equipment, always test the control system for proper functioning under
controlled conditions (that avoid hazards in the event of a control
malfunction). For additional information, refer to NEMA ICS 1.3,
PREVENTIVE MAINTENANCE OF INDUSTRIAL CONTROL AND
SYSTEMS EQUIPMENT, published by the National Electrical
Manufacturers Association, and NFPA70B, ELECTRICAL EQUIPMENT
MAINTENANCE, published by the National Fire Protection Association.
7000 "A" Frame
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