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IB 6.2.11.1-1C
Page 15
attention. These maintenance instructions only cover
circuit breakers used under the ANSI standard's usual
service conditions. Unusual conditions are covered in
ANSI Standard C37.13. The inspection of all circuit
breakers should include opening and closing the circuit
breaker electrically and manually. The unit should be
visually inspected for loose or damaged parts.
chutes, contacts, and insulation structure should be
inspected as described below.
MPSC-2000 Trip Device Removal and Installation
1. Remove the two nylon screws which retain the trip
system harness plug to the MPSC-2000 device. Retain
for re-use. If the breaker has the Voltage Interface
Module (VIM) option, disconnect the four-pin plug from
the trip unit.
2. Remove the six self-tapping screws holding the
breaker top shelf and remove the shelf with the MPSC-
2000 unit attached.
3. To reinstall, reverse the above procedure.
Metallic screws must not be used to retain the trip
system harness. Should a metallic screw fall into
the trip system, serious damage can result.
Arc Chute Removal
1. Remove the MPSC-2000 trip device according to the
instructions above.
2. Loosen the two arc chute retaining screws and
remove the screws and retainers.
3. Pull the arc chute forward slightly then lift to remove.
Arc Chute Examination
1. Discoloration or slight eroding of the metal parts can
be expected. Soot on the inside and outside of the arc
chute is usual, especially after fault interruption.
2. Metal plates or moldings that are severely burned,
cracked, or broken require arc chute replacement.
3. If the arc chute can be reused, wipe excess soot
WARNING WARNING WARNING WARNING
RISK TO PERSONNEL AND FIRE CAN RESULT IF
THE CIRCUIT BREAKER IS OPERATED WITHOUT
THE HARNESS PLUG AND SCREWS IN PLACE.
from the arc chute and blow any excess away with
clean, dry compressed air.
Arc Chute Replacement
1. Properly position the arc chute in the upper molding.
Arc
2. Position retainer and insert and tighten screw.
3. Replace the MPSC-2000 trip device observing all
recommendations and warnings above.
Contact Inspection
1. Discoloration, signs of burning, and pitting on the
arcing contacts is normal unless it interferes with
proper contact adjustment.
2. Some discoloration and pitting may be observed on
the main contacts. Again, it is detrimental only when
contact pressure adjustments are affected, or if the
available contact area has eroded significantly.
Contact Cleaning
Warning: do not use solvent-type contact cleaners
which can damage non-metallic parts.
alcohol or dichlorodifluoromethane is also prohibited.
1. Remove dust, grease, and soot on main and arcing
contacts with a clean, lint-free cloth.
2. Use non-metallic scrubbing pads like 3M Company's
"Scotch Brite" to clean more persistent burn marks and
pits on the main and arcing contacts. Take care to
prevent debris from dropping into the lower contact
structures or mechanism. Remove the debris with a
vacuum cleaner or blow away with clean, dry,
compressed air.
3. Small burrs on the arcing contacts to be removed by
filing along contour of the contact. Do not let filings fall
into the mechanism.
4. Replace badly burned and pitted contacts that do not
meet correct adjustment requirements.
5. If contacts are replaced or filed, then it is necessary
to check the contact adjustment.
NOTE: Several operations at two week intervals will
remove the effects of oxidation.
Electrical Components (EO Breakers Only)
ABB
The use of
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