Siemens 3AH3 Instruction Manual page 43

The following procedure in check list format
describes the procedure for removing and
replacing a vacuum interrupter. Components
may be identified by reference to Figures 23
and 24.
Instructions herein apply for replacement of
all vacuum interrupters except type
VS-17085 vacuum interrupters, and
interrupters on 3,000 A circuit breakers
having the flexible connector (refer to 29.1
in Figure 23) electron-beam welded to the
moving terminal (refer to 36.1 in Figure 23)
of the vacuum interrupter. These
interrupters must be replaced by factory-
trained personnel. Contact Siemens
medium-voltage customer service at 1-800-
347-6659 or 1-919-365-2200 outside the
U.S.
1. Removing the vacuum interrupter
Note: Special care needs to be exercised in
removal or installation of hardware around
the bottom, or movable contact end, of the
vacuum interrupter.
The movable contact uses a metal bellows
to maintain the vacuum seal while still
permitting up and down motion of the
contact. The bellows is rugged and reliable,
and is designed to withstand years of
vertical movement. However, care should be
exercised to avoid subjecting the bellows to
excessive torque during removal and
replacement. Twisting the bellows through
careless bolt removal or tightening may
damage the vacuum interrupter, resulting in
loss of vacuum integrity.
1.1 Before starting work, the circuit
breaker should be isolated from all
primary and control-power sources and
all stored energy discharged by
opening, closing and opening the
circuit breaker by hand. Discharge any
static charge by grounding both ends
and the middle of each vacuum
interrupter. Carefully remove outer-
phase and inter-phase barriers.
1.2 Loosen the lateral bolt(s) on terminal
clamp (29.2). Employ the illustrated
procedure to loosen clamp hardware
(refer to Figure 25).
1.3 Withdraw pin (48.5) from insulating
coupler (48.0) and levers (48.6).
1.4 Remove coupling pin from the eye bolt
(36.3).
1.5 Free struts (28.0) from the pole head
(20.0). Loosen the strut hardware on
the pole bottom (40.0) and swing the
struts forward and downward.
1.6 Loosen screws fastening the centering
ring (28.1).
1.7 Remove bolt (31.2), lock washer and
large washer at the stationary contact
of the vacuum interrupter (18 mm or
24 mm socket with extension).
1.8 Using a 24 mm socket with an
extension, loosen and remove hex-cap
screw fastening the pole head to the
post insulator. Completely remove the
pole head and set aside.
1.9 Grasp the vacuum interrupter (30.0)
and withdraw vertically. Assistance
may be required to work the terminal
clamp off the movable stem of the
vacuum interrupter. DO NOT USE
UNDUE FORCE OR TWISTING
MOTION. If the terminal clamp (29.2)
cannot be easily removed, STOP!, check
to be certain hardware is loose, and
that the terminal clamp (29.2) is not
binding.
2. Installing a vacuum interrupter
Note: Replacement vacuum interrupter
(30.0) will be received from the factory with
an eye bolt (36.3) in place, adjusted and
torqued to specific requirements. DO NOT
ALTER THE ADAPTER (EYE-BOLT)SETTING.
2.1 Inspect all silver-plated connection
surfaces for cleanliness. Clean only
with a cloth and solvent. Do not
abrade, as this will damage the silver
plating.
2.2 Insert vacuum interrupter (30.0) into
the lower pole-support (40.0). Slip
terminal clamp (29.2) into position on
the movable stem.
2.3 Align vacuum interrupter and fasten
"finger tight" using heavy flat washer,
lock washer and bolt (31.2).
2.4 Fasten the pole head to the post
insulator (16.1) "finger tight" using
hex-head bolt, lock washer and flat
washer.
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