Powered by Safety
®
20
Equipment Description
PowlVac 38™ ARM 3000A Series 4
Vacuum Circuit Breaker
01.4IB.65131
b. Interlocking
PowlVac 38
™
ARM Series 4 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 purpose of the interlocks is to
ensure:
• The circuit breaker cannot be moved
from the test/disconnect 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/disconnect position unless the
main contacts are opened.
• 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.
The PowlVac 38 ARM circuit breaker
interlocking is primarily achieved by
means of an interlock cam striker arm
attached to the racking drive shaft.
Upon initial insertion of the circuit
breaker into the compartment, a
position interlock prevents moving the
circuit breaker from the disconnected
position to the test position without the
secondary disconnect inserted.
Racking the circuit breaker in from
the test/disconnected position to the
connected position also rotates the
interlock cam attached to the racking
shaft. A cam follower, attached to a
lever pivoted on the circuit breaker
frame, drives a secondary disconnect
locking slider downward. The
secondary disconnect locking slider
engages a slot in the interlock bar
attached to the secondary disconnect
plug. The cam profile is 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 disconnected
position.
The tripping linkage and roller
under the breaker frame follow a
cam mounted in the circuit breaker
compartment. The cam, in all
intermediate positions between the
test/disconnected and connected
position, lifts the tripping roller. Lifting
the tripping roller actuates the manual
trip operator which holds the breaker
in a trip free condition. The manual trip
operator also actuates the latch check
switch, thus blocking any electrical
closing signal.
