36
Overhaul
Replacement of Vacuum Interrupters
The following procedures are for the removal and replace-
ment of the vacuum interrupters.
vacuum interrupter type, and other factors. It is
suggested that photos be taken of the circuit breaker
prior to the start of disassembly to aid in correctly
reassembling the circuit breaker.
3. Loosen, but do not remove, bolt fastening trunnion to
the movable contact stem of the vacuum interrupter.
An 8mm or a 10mm Allen wrench is required.
4. Disconnect insulating pushrod at bell cranks. Remove
and discard two 0.25” X-washer. Spread the bell crank
elements and allow the pushrod to drop down.
5. Refer to Figure 51, and using the procedure shown to
secure head and nut, proceed to loosen the bolts
which fasten the flexible shunt clamp to the movable
contact of the tube. For 2000A ratings using VS-15050
interrupters, and all 3000A ratings not using the chair
support design, it will first be necessary to remove the
heat sinks attached to each side of the flexible shunt
clamp. Keep hardware and heat sinks for reuse.
6. Remove the two X-washer (discard) fastening the bell
cranks to the trunnion.
7. Loosen, but do not remove insulating centering
devices near the movable contact end of the vacuum
interrupter.
8. Remove the bolt fastening the trunnion to the end of
the interrupter. Be certain to save the washer, spacer,
trunnion and hardware for later use.
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The movable contact uses a metal bellows assembly to maintain the
vacuum seal while still permitting up and down motion of the contact.
This bellows assembly is rugged and reliable, and is designed to withstand
years of vertical movement. However, care should be exercised in
subjecting the bellows to excessive torque during removal and replace-
ment. Twisting the bellows through careless bolt removal or tightening
may damage the vacuum interrupter.
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VS-12015 1200 and 2000 A 48
VS-10006 1200 A 47
VS-10006 2000 A 50
VS-25002 1200 and 2000 A 48
VS-17006 1200 and 2000 A 48
VS-10028 1200 A 47
VS-10028 2000 and 3000 A 49
VS-15050 1200 A 53
VS-15050 2000 and 3000 A 54
VS-15050 3000 A 55
Circuit Breaker Side Elevation (typical) 46
Interrupter Clamp Fastening Procedure 51
Gaging Procedure & Stroke Adjustments 52
RReeffeerreennccee TTaabblleess aanndd LLiisst
tss
Recommended Tools Table 6
Fastener Torque Limits Table 7
Preparation
Identify vacuum interrupter family and breaker continuous
current rating. The interrupter will have an identifying
nameplate showing the family designation and the contin-
uous current requirement can be taken from the circuit
breaker’s rating label.
Check the “Index of Figures” to find the appropriate side
elevation picture of the circuit breaker pole unit assembly.
Confirm that the figure applies by comparing the figure
carefully to the circuit breaker.
Read through the replacement procedures, noting recom-
mended tools, gaging requirements and torquing limits, etc.
Vacuum Interrupter Removal
1. Make provision to save and retain hardware. Rejoin
fastener parts (bolts, nuts, washer, lockwashers, etc.) as
they are removed. Save in an appropriate container.
2. Remove interphase and outer barriers as required.
Carefully note the exact sequence and arrangement of
barriers and supports, so that these parts can be
correctly positioned during reassembly. Barrier and
support arrangements vary by circuit breaker rated
voltage, continuous current, interrupting current,
9. Vacuum Interrupter Stationary Contact Disassembly
and Interrupter Removal.
9.1. Circuit breakers rated 1200 and 2000A using the
VS12015, VS 25002 or VS17006 Interrupters (Figure
48). Using an 19mm socket and extension, remove
bolt fastening vacuum interrupter stationary contact to
the upper primary connectors and upper stab support.
Save bolt washer and lockwasher. Carefully remove
and set aside the heavy copper spacer connecting the
interrupter to the upper primary bars. Handle with care
to maintain flat ends on the cylindrical spacer.
9.2. Circuit breakers rated 1200A using the VS10006 or
VS10028 interrupters (Figure 47). Using 9/16 (and
11/16) socket and backup wrench, remove two 3/8
fasteners joining upper primary extensions to the stab
support. Rejoin hardware and save with primary exten-
sions for reuse. Using a 24mm socket and extension,
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It is critical that these spacing washer be replaced in their exact order
upon reassembly to assure proper operation of the circuit breaker.
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