Safety POWELL PowlVac-ND 4 Series, Instruction Bulletin

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18 Equipment Description
01.4IB.77020
PowlVac-ND
®
and PowlVac-NDA
™
Series 4
Vacuum Circuit Breakers
d. Operating Solenoids
Electrical operation of the circuit
breaker is accomplished using
operating solenoids.
The closing coil (Figure 4, aa) is an
operating solenoid that is located at
the bottom center of the mechanism,
and is assembled to the circuit breaker
base pan by bolts accessible from
underneath the circuit breaker.
The primary shunt trip coil
(Figure 4, f) is located at the top left side
of the mechanism, and is assembled to
the lower frame channel by two bolts.
Either a secondary shunt trip coil or an
undervoltage device may be furnished
as an option. When furnished, either of
these devices will be located at the top
right side of the mechanism, installed
on the lower frame channel. Only one
of these two operating solenoids may
be furnished on any one circuit breaker,
as both devices are located in the same
space.
e. Control Circuit
Typical AC and DC electrical control
schemes are shown in Figure 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 operation sequence for all control
schemes is shown in
Figure 7
. 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.
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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-ND® Series 4 circuit breaker are
shown and described in the following
sections:
a. Breaker Position Indicator
The breaker position indicator
(Figure 3, e) 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
“CONN”
, and this is fully visible
in the aperture, the circuit breaker is
in the connected position. When the
breaker position indicator displays
“TEST”
, 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,
E. Racking Procedures for the
PowlVac-ND® Series 4 Circuit Breaker
for more information.