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10
Construction
Each of the circuit breaker poles are fixed to
the pole support channel by two cast-resin
insulators. The insulators also connect to the
fixed- and moving-end pole heads that in turn
support the ends of the vacuum interrupter.
The pole supports are aluminum castings or
sheet steel (for 15.5 kV and 27.6 kV up to
25 kA). Refer to Figure 1: Operator panel
controls of circuit breaker and manual
charging of closing spring and Figure 2:
Vacuum circuit breaker operator module on
page 8, Figure 5: Pole assembly on page 11
and Figure 6: Stored-enegy operating
mechanism (circuit breaker shown in OPEN
position) on page 12.
The energy-storing mechanism and all the
control and actuating devices are installed in
the operator housing. The mechanism is of
the spring stored-energy type and is
mechanically and electrically trip free.
The close-open indicator, closing spring-
charge indicator and the operation counter
are located on the front of the operator
housing.
The control connector for the control and
signalling cables is a multi-contact plug. The
mating control plug wiring connects to the
terminal blocks in the relay and control
compartment.
Circuit breaker pole (refer to Figure 5
Figure 5: Pole assembly on page 11)
The vacuum interrupter is bolted to the fixed-
end pole head, which is rigidly connected to
the pole support channel by the post
insulator. The moving contact end of the
vacuum interrupter is stabilized against lateral
forces by a centering ring on the moving-end
pole head. The external forces due to
switching operations and the contact
pressure are absorbed by the struts.
Current-path assembly (refer to
Figure 5: Pole assembly on page 11)
The current-path assembly consists of the
fixed-end pole head, the stationary contact
and the moving contact, plus a flexible shunt
between the moving contact terminal clamp
and the moving-end connection pad.
Vacuum interrupter (refer to Figure 5:
Pole assembly on page 11)
The moving-contact motion is aligned and
stabilized by a guide bushing. The metal
bellows follows the travel of the contact and
seals the vacuum interrupter against the
surrounding atmosphere.
Switching operation (refer to Figure 5: Pole
assembly on page 11 and Figure 6: Stored-
energy operating mechanism (circuit breaker
shown in OPEN position) on page 12)
When a closing command is initiated, the
closing spring (62.0), that was previously
charged by hand or by the motor, actuates
the moving contact through the jack shaft
(63.0), lever (63.1, 63.3 and 63.5), contact
pressure spring (49.0), insulating coupler
(48.0) and angled lever (48.6).
The forces that occur when the action of the
insulating coupler (48.0) is converted into the
action of the moving contact along the axis of
the vacuum interrupter are absorbed by the
guide link (48.9), that pivots on the pole
bottom and the eye bolt.
During closing, the opening spring (64.0)
(refer to Figure 6: Stored-energy operating
mechanism (circuit breaker shown in OPEN
position) on page 12) and the contact
pressure springs (49.0) are charged and
latched by pawl (64.2). The closing spring
(62.0) (refer to Figure 6: Stored-energy
operating mechanism (circuit breaker shown
in OPEN position) on page 12) of the motor-
operated circuit breaker is recharged
immediately after closing.
In the closed state, the necessary contact
pressure is maintained by the contact
pressure springs (49.0) and the atmospheric
pressure. The contact pressure spring
automatically compensates for arc erosion,
which is very small.
When a opening command is given, the
energy stored in the opening and contact
pressure springs (49.0) is released by pawl
(64.2). The residual force of the opening
spring (64.0) maintains the moving contacts
in the open position.
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