39
Overhaul
Align vacuum interrupter stationary contact. Insert M16
hex bolt through lock washer, washer, upper stab
support and primary bus extensions. Manually engage
bolt into the tube by applying hand torque only.
Now it is time to secure the hardware connecting the
insulating plates on each side of the pole to the lower
pole support. Use four (two on each side) hex socket
flat head screws. Clean external and internal threads.
Apply “Loctite” Primer T to the external and internal
threads. Apply “Loctite“ thread locker 262 to the
external threads. Engage and torque to 8-10 ft-lbs.
15. Trunnion and Movable Contact Adjustment
15.1. The trunnion is fitted to the interrupter movable stem
in concert with spacer and shim washer. A special tool
consisting of a threaded shaft and gage block is to be
used to determine the correct number of shimming
washer. Gaging tool consists of:
Note: VS10028 Interrupter will not require a spacer.
Threaded Shaft
M12
18-658-137-105
Threaded Shaft
M10
18-658-137-102
Gage Block
6mm:
18-750-171-001
Gage Block
8mm:
18-750-171-002
Gage Block
11mm: 18-750-171-003
Gage Block
9mm:
18-750-171-004
VS12015 requires 6mm gage and stroke
VS25002 requires 8mm gage and stroke
VS17006 requires 8mm gage and stroke
VS10028 requires 8mm gage and stroke
VS10006 requires 11 mm gage and stroke
VS15050 requires 9mm gage and stroke
The gage will set the trunnion center at one half the
stroke magnitude above the center of the bell crank’s
major pivot. The gage block includes allowances for
trunnion thickness, 1/2 the stroke and radius of the
major bell crank pivot (
Figure 52
).
15.2. Torque fastener at the interrupter stationary contact
to fix the tube stationary contact against the primary
extensions, using torque shown in
Table 7
. The
companion lock washer is to be fully collapsed. Hold
interrupter in the alignment required under Article 12 of
the vacuum interrupter replacement procedure while
tightening this fastener.
15.3. Thread gaging shaft, by hand, into movable stem of
the vacuum interrupter.
M10 thread for VS12015, VS25002 and VS17006.
M12 thread for VS15050.
M12 thread for VS15050.
Thread by hand until fully and firmly seated.
15.4. Apply shim washer, approximately 7, spacer and
correct gage block over the shaft. Raise the gage block
until the gage foot just bears or comes within one
washer thickness of bearing upon the lower surface of
the bell crank shaft. washer may have to be removed
or added to achieve these conditions. The spacer and
washer above the gage block must be packed against
the vacuum interrupter movable stem when observa-
tion of the gage foot to bell crank clearance is made.
The gage foot must just touch the shaft or be within
one shim washer thickness of doing so.
Note:
The VS10028 interrupter will not require a
spacer.
15.5. Having determined the required number of washer,
insert hex bolt through lockwasher, trunnion, spacer
and shim washer. Engage bolt into the vacuum inter-
rupter stem and tighten by hand to snugness. Engage
trunnion to bell crank (both sides) and tighten hex bolt
further until lockwasher is just collapsed.
15.6. Manually exercise bell cranks, moving interrupter
contact approximately 1/4 to 3/8 of an inch. Release
bell cranks, interrupter contact should snap freely to
the closed position. The main contacts should be
clearly heard as they meet upon closing.
Check to make certain the insulating centering blocks
or rings at the base of the interrupter are loose to
permit interrupter alignment. It may be necessary to
repeatedly free the interrupter stationary fastener,
shift the interrupter slightly, retighten and recheck bell
crank snap action closing until full movable contact
freedom is assured.
15.7. Once free movement of the movable contact is
achieved, the interrupter centering blocks or ring may
be fastened. Select two X-washer from parts kit and
crimp into grooves at each end of the trunnion.
16. Open Stroke Adjustment
The open position is established by the insulating
coupler which when adjusted to the proper length, and
attached to the bell cranks, will hold the interrupter
open at the proper contact gap or separation.
In Article 15, the trunnion shaft center was set at one
half the required vacuum interrupter stroke above the
bell crank shaft horizontal center line. The open position
will be established with the trunnion shaft center one
half the required vacuum interrupter stroke below the
bell crank shaft horizontal centerline.
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Thread damage will occur if threads are crossed. Be sure the bolt can be
fully engaged with light manual torque.
