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PowlVac® CDR 27kV & 38kV Vacuum Circuit Breaker
IB-65020A
Equipment Description
Ch 3 Equipment Description
A. G
enerAl
The PowlVac® CDR 27kV & 38kV vacuum circuit
breakers (Figure 1) are closed door racking
(CDR) circuit breakers. These circuit breakers
use sealed vacuum interrupters
(Figure 2, c) to control the primary circuit.
Primary connections to the associated
metal-clad switchgear are made by tubular
busbars terminating in the finger clusters of
the primary disconnects (Figure 2, a & d). The
primary disconnecting devices, busbars, and
vacuum interrupter assemblies are supported
by high voltage insulators (Figure 2, e)
specifically designed for the application.
The primary current path side of the circuit
breaker is considered the rear of the circuit
breaker, while the side with the cover
containing the various indicators and manual
operators is considered the front of the
circuit breaker. By removing the front cover,
the operating mechanisms of the circuit
breaker are exposed. The stored energy
mechanism assembly provides motion to
each of the vacuum interrupters moving
contact assemblies through contact operating
pushrods.
B. t
he
S
tored
e
nerGy
M
echAnISM
1) Mechanical Description
The stored energy mechanism is located in
the front of the circuit breaker behind the
front cover. The front cover is held in place
with cover bolts (12) (Figure 1, i). The bolts
may be removed to allow access to the
stored energy mechanism and its interlocks,
auxiliary switches, and other control
devices.
CAUTION
CAUTION
!
Prior to removing the front cover, the user
must make sure the circuit breaker is in the
OPEN position and the main closing spring is
fully discharged. Failure to do so may result in
injury.
On the escutcheon of the stored energy
mechanism, there are two (2) indicators
that show the various states of operation
of the mechanism and two (2) manual
operators that will open/close the stored
energy mechanism. The circuit breaker
nameplate (Figure 1, h) is also located on
the mechanism escutcheon. If for any
reason the escutcheon is removed from the
circuit breaker, it shall be verified that the
serial number contained on the nameplate
matches the engraved serial number plate
(figure 2, j) permanently affixed to the
rear of the circuit breaker frame prior to
installing the escutcheon.
The mechanism employed in the circuit
breaker is a stored energy system which
uses a charging motor to compress the
main closing spring. The energy stored in
the main closing spring is released during
the closing operation. The released energy
allows the mechanism to close the vacuum
interrupter contacts, compress the contact
loading springs, charge the opening
springs, and overcome frictional forces.
When the circuit breaker is opened, the
energy stored in the opening and contact
loading springs is released, and the vacuum
interrupter contacts are opened.
