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17
Equipment Description
IB-60201
e. Control Circuit
The typical AC and DC electrical control
schemes are shown in Figures 7 & 8. The
control scheme of any particular circuit
breaker may differ from these typical
schemes depending on the user’s
requirements, operating solenoids, and
the control devices furnished with that
circuit breaker.
The sequence of operation for all
control schemes is shown in
Figure 6. Circuit breaker mounted
auxiliary contacts not used in the
control circuit are brought out for
control and indication functions. The
metal-clad switchgear equipment
may provide a circuit breaker MOC
(Mechanism Operated Cell Switch) for
additional contacts.
c. r
AckInG
M
echAnISM
1) General Description
The racking mechanism is the mechanical
assembly that facilitates moving the circuit
breaker between the breaker
test/disconnected and the connected
positions in the circuit breaker
compartment. The main racking
mechanism components for the PowlVac®
Standard Racking Circuit Breaker (STD)
are shown and described in the following
sections:
a. Breaker Position Indicator
The breaker position indicator
(Figure 1, c) is visible through an
opening in the circuit breaker front
cover. The indicator displays whether
the circuit breaker is in the connected or
the test/disconnected positions. When
the breaker position indicator displays
“BREAKER CONNECTED”
, and this is
fully visible in the aperture, the
circuit breaker is in the connected
position. When the breaker
position indicator displays
“BREAKER TEST/DISCONNECTED”
,
and this is fully visible in the aperture,
the circuit breaker is in the
test/disconnected position. In
positions other than the connected
and test/disconnected positions, the
breaker position indicator does not
display an indication. Refer to
Ch 4 Installation
,
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b. Interlocking
PowlVac circuit breakers are provided
with several interlocks that operate in
conjunction with the circuit breaker
compartment to ensure the proper
operation of the circuit breaker. Do
not attempt to modify or bypass these
interlocks, as they are necessary for the
safe operation of the circuit breaker.
The following describes the interlocking
for the standard circuit breaker.
The purpose of the interlocks is to
ensure:
• The circuit breaker cannot be moved
from the test/disconnected to the
connected position unless the main
circuit breaker contacts are opened
and the secondary control circuitry
from the compartment to the circuit
breaker is completed, and the circuit
breaker cannot be removed from the
connected to the test/disconnected
position unless the main contacts
are opened.