Overhaul - Siemens 3AH3 Instruction Manual

Circuit Closing
breaker type operations
10,000
SDV6
operations
10,000
All others
operations
Table 6: Overhaul schedule
42

Overhaul

Introduction
The following procedures along with the
troubleshooting charts in this instruction
manual (refer to pages 47-51), provide
maintenance personnel with a guide to
identifying and correcting possible
malfunctions of the circuit breaker.
Circuit breaker overhaul
Table 6 gives the recommended overhaul
schedule type 3AH operating mechanisms.
These intervals assume that the circuit
breaker is operated under "usual service
conditions" as discussed in ANSI/IEEE
C37.20.2 section 4 (for drawout circuit
breakers) or ANSI/IEEE C37.04 section 4 and
elaborated in C37.010 section 4 (for
outdoor distribution circuit breakers). If the
circuit breaker is operated frequently, the
overhaul interval in Table 6 may coincide
with the maintenance interval in Table 2.
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
according to overhaul schedule (refer to
Table 6)
Close coil, 52SRC
Trip coil, 52T
Trip-free drive bar mechanism (if
applicable).
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 interrupter; instructions
follow.
2. Close coil (52SRC) and trip coil (52T).
a) Remove two "push on" terminal
connections
b) Remove two M4 hex-head screws and
remove solenoid.
c) Install replacement coils with new M4
x 10 hex-head screws (Siemens part #
00-000-443-820) and new lock
washers for M4 (Siemens part #
00-000-288-316).
d) The coil-mounting screws must be
installed using thread locking
adhesive (Loctite #222, Siemens part
15-133-281-007) and primer (Loctite
primer T (#7471), Siemens part
15-133-281-005).
e) Connect wires to coils with new wire
terminals (Siemens part #
15-171-600-002).
3. Lubricate operating mechanism
according to maintenance and
lubrication information (refer to page
32).
4. When work is finished, operate circuit
breaker and close and open several
times, and check that all screw
connections are tight.
Replacement of vacuum interrupters
It is recommended that vacuum interrupters
be replaced only by a qualified Siemens field
service representative. The information in
the following sections is provided to aid in
understanding the replacement procedures.
Vacuum interrupters for type 3AH rated
63 kA interrupting or rated 3,000 A
continuous current and all type 3AHc
operators require special expertise for
replacement and must be replaced only by a
qualified Siemens field service
representative. Accordingly, detailed
instructions for replacement vacuum
interrupters for these ratings are not
provided in this instruction manual.
Replacement vacuum interrupters are
furnished as a complete assembly. They
have been completely tested and
dielectrically and mechanically conditioned.
It is recommended that one vacuum
interrupter be removed and replaced
completely rather than removing two or
more vacuum interrupters at a time.