37
Cell Preparation
The cell contains the positioning, interlocking and operating
devices described below and shown in
Figures 33
and
35.
These
devices must be checked for placement and freedom of operation.
Circuit Breaker Racking Mechanism
The circuit breaker racking mechanism is centered below the
circuit breaker. It functions in conjunction with the trip-free
interlock on the circuit breaker, to hold the circuit breaker trip-
free between positions. Three positions are provided: DIS-
CONNECT, TEST, and CONNECT.
Figure 33.
Circuit Breaker Compartment
Interference Blocking Plate
This plate is mounted vertically on the bottom of the cell to
allow only the properly rated breaker into the designated cell
(e.g., a 1200 ampere circuit breaker to enter a 1200 ampere
cell, or a 2000 ampere circuit breaker to enter a 2000 ampere
cell), depending on the voltage, interrupting, and close and
latch ratings. Normally the cubicle and circuit breaker rating
plate combinations will be identical.
The interlock will allow a 2000 ampere circuit breaker to enter
a 1200 ampere cell, provided the voltage, interrupting, and
close and latch ratings equal or exceed the ratings of the cell.
The coordinating interference plate on the circuit breaker is
shown in
Figure 34
.
Figure 34.
Interlocks on Bottom of Circuit Breaker
Secondary Disconnect
The secondary disconnect contains all the electrical control
circuit connections for the circuit breaker. It mates with the
secondary disconnect block on the circuit breaker. The circuit
breaker contacts slide against the cell contact strips. The
secondary contacts are automatically mated in the TEST and
CONNECT positions.
Mechanism Operated Cell Switch (MOC)
This switch is operated by a roller on the circuit breaker. The
breaker engages the MOC auxiliary switch only in the CONNECT
(operating) position unless an optional TEST position pickup is
specified in the contract. If a TEST position pickup is included,
the breaker will engage the auxiliary switch in both positions.
The MOC switch is illustrated in the lower portion of
Figure
35
. Up to 24 stages may be provided.
Truck Operated Cell Switch (TOC)
This switch is operated by an extension of the top plate at the
right top corner of the circuit breaker. This switch is operated
only as the circuit breaker is moved to or from the CONNECT
position. The TOC switch is shown in the upper portion of
Figure 35
. Up to 12 stages may be provided.
Circuit Breaker Position
Hazardous voltages.
Can cause death, severe personal injury or
property damage.
Do not insert a circuit breaker into a cell intended
for a circuit breaker with ratings above those
of the circuit breaker being inserted.
Verify that circuit breakers and cubicles have
appropriate ratings and properly located inter-
ference blocking plates and angles before
attempting to insert a circuit breaker.
WARNING
1577-95
21663-93
Control
Power
Disconnects
Ground
Disconnect
Rating
Interlock
Trip Free
Interlock
ClosedBreaker
Interlock
Racking Interlock/
Spring Dump
Racking
Block
Ground Bar
Rating
Interlock
Breaker
Release
Latch
Racking
Mechanism
