Operation
clear. This releases the motor cut-off switch (MCO). When the
MCO switch opens, the motor stops, and the closing coil
circuit is set up through one side of the MCO switch.
The circuit breaker can now be closed by depressing the
latch hood (50) or by energizing the closing coil (CC) through
the external close control switch (CSC). When the close circuit
is energized, the
"Y"
relay is energized and opens the
"Y"
contact in the closing circuit. This prevents "pumping" or
repeated attempts to close the circuit breaker if a tripping
signal or fault is present. This would happen if the closing
switch (CSC) is bypassed by a short circuit, or if it is defective.
A combination manually and electrically operated circuit
breaker is also available. This includes both the motor-gear
charging system as well as the manual charge handle .
N ote:
Manual charging handle m ust b e i n vertical position
during electrical charging.
Drawout Interlock
A drawout circuit breaker mechanism i ncludes:
1 .
Means to rack the circuit breaker in or out of the cubicle
compartment.
2.
interlocks to prevent racking a closed circuit breaker into
or out of any position.
3. Interlocks to prevent closing a circuit breaker until it is
racked to the TEST or CONNECTED position.
4.
Interlocks to prevent withdrawing a circuit breaker from
the cubicle while the closing springs are charged.
Racking
Mechanism
Refer to
Figure
4. With the circuit breaker resting on the
cubicle rail, the foliowing sequence should be used to rack
the circuit
breaker into the cubicle.
1 . Push trip bar in, open racking window and insert racking
crank.
Note:
Racking window cannot be opened unless manual
trip bar is pressed in. While the trip bar is pressed in, the
circuit breaker is TRIP FREE and cannot be closed.
2.
With the racking
crank,
rotate the racking screw ( 1 05)
counterclockwise until the racking shaft is in the discon
nected position . The racking clevis can now engage the
racking pins in the cubicle. The circuit breaker should
now be pushed along the rail into the DISCONNECTED
position. Double check that the racking clevis does
engage the pins i n the cubicle.
3.
Clockwise rotation of the racking screw will rack the
breaker into the TEST position. At the TEST position, the
racking window can be closed, allowing the trip bar to
reset and the circuit breaker can be operated. Further
racking will place the circuit breaker between the TEST
and fully CONNECTED positions. Between positions, the
interlock bar wil l not engage the position holes of the
cubicle. The breaker will be held TRIP FREE and cannot
be closed.
In
the CONNECTED position , the interlock will engage the
cubic:e hole and reset. allow:ng the
circuit
oreaker to be
closed. This prevents closing a circuit breaker which
is
not
in
the CONNECTED or TEST position.
4.
To withdraw the breaker from the CONNECTED position,
rotate the racking screw counterclockwise.
5. Before attempting to operate the circuit breaker, the posi
tion of the device should be checked with reference to the
holes in the cubicle. to be certain that it is fully connected.
See adjustments.
Page 1 1
for proper procedure.
I M P O R TANT: To avoid d a m a g e to the racking
mechanism, when in the CONNECTED position, d o not
forcefully rotate the racking crank clockwise.
1 09
1 1 0
R
ac
ki
n
g
Figure 4.
Detail of Typical Racking
Mechanism and
Drawout Interlock
Spring Discharge Interlock
When racking the circuit breaker out to the DISCONNECTED
position, the closing springs will automatically discharge, at
or before reaching the DISCONNECTED position. The barrel
nut engages the spring interlock. This, in turn. is connected
to the manual close hood which releases the closing springs.
IMPORTANT: On manually charged breakers, the close
hood is interlocked to the manual charge cam, and must
be clear before racking the circuit breaker to the DISCON
NECTED position. For this reason, the manual charge
handle must be in the vertical position during racking.
Note:
The racking mechanism must be returned to the TEST
position before closing s prings can be charged (either i n the
cubicle or when removed from the cubicle).
The spring discharge interlock produces TRIP FREE opera
tion in which ali of the stored energy of the springs is dis
sipated in the mechanism. It is preferable to turn the motor
power off in the TEST position , close and trip the circuit
breaker norma!!y in that position, and then rack out in the
normal manner.
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