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Equipment Description
PowlVac
®
STD Vacuum Circuit Breaker
IB-60201
• The control circuits cannot be
broken when the circuit breaker is in
the connected position.
• The circuit breaker cannot be
removed from the circuit breaker
compartment with the circuit
breaker closed or with the main
closing spring charged.
Standard circuit breaker interlocking
is primarily achieved by means of a
racking drive shaft shutter and an
interlock bar attached to the secondary
disconnect receptacle.
A racking drive shaft shutter on the
front of the circuit breaker restricts
access to the racking drive shaft. The
shutter cannot be moved downward
until the manual trip operator is pushed
inward and the secondary disconnect
plug is fully inserted. This assures that
the circuit breaker is “open” and the
control circuits are connected prior to
allowing access to the racking drive
shaft.
The shutter is pivoted on the frame of
the circuit breaker and has a projecting
pin that engages a slot in a cam on
the racking shaft. This cam has two
(2) slots arranged so that the shutter
can only be in its upward position
when the racking crank arms are fully
in the test/disconnected or connected
position. Since the manual trip
operator is mechanically held in the
inward (actuated) position when the
shutter is down, and the shutter can be
raised in only the test/disconnected or
connected positions due to the pin and
cam arrangements the circuit breaker
is held in a trip-free condition in any
position except the test/disconnected
or connected position. The manual trip
operator also actuates the latch check
switch, thus blocking any electrical
closing signal.
Moving the shutter downward also
moves a secondary disconnect
locking bar downward. The locking
bar engages a slot in the interlock bar
attached to the secondary disconnect
plug. The locking bar is connected to
a lever that is pivoted on the frame of
the circuit breaker and has a projecting
pin that engages a slot in a cam on the
racking shaft. This cam has one (1) slot
arranged so that the lever can only be
in its upward position when the racking
crank arms are fully in the
test/disconnected position. This
ensures that the control circuits cannot
be disconnected in any position except
the test/disconnected position.
The interlock bar attached to the
secondary disconnect also actuates the
secondary trip prop shaft and the close
latch upon removal from the circuit
breaker. This final interlock ensures
that the circuit breaker is in the open
position and the main closing spring is
discharged prior to removal from the
compartment.