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Equipment Description
PowlVac
®
STD Vacuum Circuit Breaker
IB-60201
4) TOC (Truck Operated Cell Switch) Actuator
The TOC, located in the switchgear, is
operated by circuit breaker truck position.
To accomplish this, a TOC actuator
(Figure 3, a) is located on the right top of
the circuit breaker frame and it is designed
to strike the TOC as the circuit breaker
travels to the connected position.
5) Ground Connection
The ground connection is an assembly
of spring-loaded fingers that effectively
grounds the circuit breaker frame as
it is inserted into the circuit breaker
compartment. The ground connection
(Figure 3, p) is located at the rear edge of
the floor pan of the circuit breaker between
the center and right poles of the circuit
breaker. An extension of the
metal-clad switchgear ground bus is
secured to the circuit breaker compartment
floor and engages the ground connection
as the circuit breaker is placed into the
disconnected position. The ground
connection system remains engaged in all
subsequent positions of the circuit breaker
until the circuit breaker is removed from the
compartment.
6) Shutter Rollers
The circuit breaker travels between the
test/disconnected and connected positions
as the crank arm rollers (Figure 3, k)
engage the vertical slots of the racking
cams attached in the circuit breaker
compartment. This action also drives
the compartment shutters to open/close
which allows the primary disconnecting
devices to connect/disconnect. Downward
movement of the crank arms rollers in the
slots will move the shutters to the fully
open position before the circuit breaker
travels towards the connected position.
7) Anti-Rollout Latch
The circuit breaker is equipped with an
anti-rollout latch (Figure 3, h) which
prevents inadvertent removal from the
circuit breaker compartment by engaging a
block in the circuit breaker compartment.
e. v
AcuuM
I
nterrupterS
PowlVac® circuit breakers utilize sealed vacuum
interrupters to control the primary circuit.
Some vacuum interrupters appear to be
identical in size and shape externally, but types
vary in rating due to the differences in their
internal construction. Refer to
Table E, Primary
Current Path
for a listing of vacuum interrupters
used in PowlVac STD circuit breakers.
f. v
AcuuM
I
nterrupter
c
onnectIon
Connection to the vacuum interrupter stems
are made by means of copper contact blocks.
The top stem of the vacuum interrupter
is threaded and a copper contact block is
screwed onto the stem. The contact block and
the vertical connector bars are bolted together
and the vertical connector bars in turn are
assembled to the upper primary disconnecting
devices of the circuit breaker. Another copper
contact block is mounted to the bottom or
moving stem of the vacuum interrupter. The
sliding contact finger assembly (Figure 3, r)
makes contact with this block and the lower
primary disconnecting devices. The multiple
parallel paths of the sliding contact finger
assembly keeps the current density low.
