IB131021EN
Page
xxxi
Effective Mar 2018
The circuit breaker levering latch can be disengaged only
when the circuit breaker is in the TEST position by lifting the
latch release. As the circuit breaker is withdrawn, it comes
out with the contacts open and the springs discharged
because of the floor tripping and spring release interlocks.
5-7
OPERATIONS COUNTER
All circuit breakers are equipped with a mechanical
operations counter. As the circuit breaker opens, the profile
of the bottom output plate advances the counter arm
reading by one (Figure
3-5
)
.
5-8
GROUND CONTACT
The ground contact is an assembly of spring loaded fingers
providing a disconnectable means for grounding the circuit
breaker chassis, after it has been inserted into a switchgear
structure. The ground contact is located on the left side of
the circuit breaker under the mechanism bottom pan. An
extension of the switchgear ground bus is secured to the cell
floor in such a position to engage the ground contact
automatically, when the circuit breaker is moved into the
TEST position. It remains engaged in all other circuit
breaker positions within the cell (Figures
4-2
and
4-4
)
.
5-9
MOC AND TOC SWITCH OPERATIONS
The MOC (mechanism operated control) switch operator is
coupled to the pole shaft (Figure
4-4
)
.
In the TEST and
CONNECTED positions of the circuit breaker, the operator
aligns directly above the MOC switch bell crank levers in
the compartment. As the circuit breaker closes, the
operator moves down and pushes the bell crank lever to
change the MOC switch contact position. Thus, the MOC
switch contacts operate in the same manner as the
auxiliary switch contacts in the circuit breaker. Although the
MOC switch operator is provided on all circuit breakers, the
compartment mounted MOC switches are only provided
when specified with the switchgear order.
The TOC (truck operated control) switch operator is
mounted inside the right foot of the circuit breaker (Figure
4-4
)
.
It operates the TOC switch as the circuit breaker
moves to the CONNECTED position in the switchgear
compartment.
SECTION 6: INSPECTION, MAINTENANCE AND
TROUBLESHOOTING
6-1
INTRODUCTION
WARNING
DO NOT WORK ON A BREAKER ELEMENT WITH
PRIMARY POWER APPLIED.
DO NOT WORK ON A BREAKER ELEMENT WITH
SECONDARY CONTACTS CONNECTED.
