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 38-3AH3
vacuum circuit breaker.
Table 5 gives the recommended overhaul
schedule for a type 38-3AH3 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.
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.
Table 5: Overhaul schedule
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,
Vacuum interrupters as determined by
vacuum-integrity test, contact erosion
or after 10,000 operations
Spring-release coil, 52SRC
Shunt-trip coil, 52T
Trip-free drive-bar mechanism.
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 dismount solenoid.
C. Install replacement solenoids with
two M4 hex-head screws and new