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Equipment Description
01.4IB.77020
Ch 3 Equipment Description
A. G
enerAl
D
eScrIptIon
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improvement.
It is possible that improvements occurred
between revisions to this document and
therefore, may not be described in these
instructions. If the equipment does not
resemble the photographs and descriptions
contained herein, contact Powell before
attempting to perform any actions.
NOTICE
PowlVac-ND® Series 4
and
PowlVac-NDA™ Series 4
Vacuum
Circuit Breakers use sealed vacuum interrupters
to control the primary circuit. The
primary connections to the associated
metal-clad switchgear are made by parallel
copper busbars terminating in multiple contact
fingers of the primary disconnecting devices
. The primary disconnecting
devices, busbars, and vacuum interrupter
assemblies are supported by insulating
supports
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 interrupter moving contact assemblies
through operating pushrods
. In
the same metal enclosed compartment as the
stored energy mechanism is the circuit breaker
racking mechanism and interlocks which
control the movement of the circuit breaker
between the test/disconnected and connected
positions. The racking mechanism provides
the motion to engage/disengage the primary
disconnecting devices and to
open/close the shutters in metal-clad
switchgear.
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
by ten (10) cover bolts
that
may be removed, allowing access to the
stored energy mechanism and its interlocks,
auxiliary switches, racking mechanism, and
other control devices.
!
CAUTION
Prior to removing the front cover, ensure 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
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
permanently affixed to the
rear of the circuit breaker frame prior to
installing the escutcheon.
