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Overhaul
Introduction
The following procedures along with the
troubleshooting charts at the end of this
section, provide maintenance personnel with
a guide to identifying and correcting possible
malfunctions of the type GMSG vacuum
circuit breaker.
Circuit breaker overhaul
Table 6: Overhaul schedule gives the
recommended overhaul schedule for a type
GMSG vacuum circuit breaker. These intervals
assume that the circuit breaker is operated
under "usual service conditions" as discussed
in ANSI/IEEE C37.20.2, section 8.1 and ANSI/
IEEE C37.04, section 4, and elaborated in
ANSI/IEEE C37.010, section 4 for type GMSG
non-generator circuit breakers. For generator
circuit breakers, these service conditions are
defined in ANSI/IEEE C37.20.2, section 8.1
and ANSI/IEEE C37.013, section 4.2. If the
circuit breaker is operated frequently, the
maintenance interval in Table 6: Overhaul
schedule may coincide with the maintenance
interval in Table 2: Maintenance and
lubrication schedule on page 40.
When actual operating conditions are more
severe, overhaul periods should occur more
frequently. The counter on the front panel of
the circuit breaker records the number of
operations.
High-potential tests employ hazardous voltages.
Will cause death, serious injury and property damage.
Read instruction manual. All work must be performed with the circuit
breaker completely de-energized and the springs discharged. Limit work
to qualified personnel.
Replacement at overhaul
The following components are replaced
during an overhaul of the circuit breaker,
when required:
Vacuum interrupters as determined by
vacuum-integrity test, contact erosion or
after 10,000 operations
Spring-release coil, 52SRC
Shunt-trip coil, 52T
Auxiliary switch.
When these parts are changed, locking
devices must also be removed and replaced.
These include lock washers, retaining rings,
retaining clips, spring pins, cotter pins, etc.
1. Replace vacuum interrupters, instructions
follow (refer to page 49).
2. Spring-release coil (52SRC) or shunt- trip
coil (52T).
A. Remove two "push on" terminal
B. Remove two M4 hex-head screws and
C. Install replacement solenoids with
connections
dismount solenoid.
two M4 hex-head screws and new
lock washers.
Circuit
Number of
breaker type
closings
GMSG
10,000
GMSG-GCB
10,000
Table 6: Overhaul schedule
53
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