I.B. 3A74792H04
Page 20
Effective 7/97
The closing spring cranks have spring ends connected
to them, which are in turn coupled to the closing springs.
As the cranks rotate, the closing springs are charged.
When the closing springs are completely charged, the
spring cranks go over dead center, and the closing stop
roller comes against the spring release latch. The clos-
ing springs are now held in the fully charged position.
Closing springs may also be charged manually. Insert
the maintenance tool in the manual charging socket.
Move it up and down approximately 38 times until a
clicking sound is heard, and the closing springs charg-
ing indicator indicates “Charged.” Any further motion of
the maintenance tool will result in free wheeling of the
ratchet wheel.
5-3.3 CLOSING OPERATION
Figure 5-4 shows the position of the closing cam and
tripping linkage. Note that in Figure 5-4a in which the
circuit breaker is open and the closing springs are dis-
charged, the trip “D” shaft and trip latch are in the
unlatched position.
Once charged, the closing springs can be released to
close the circuit breaker by moving the spring release
latch out of the way. This is done electrically or manually
by depressing the spring release lever, which turns the
spring release latch out of the way of the closing stop
roller. The force of the closing spring rotates the cam
shaft through the spring cranks. The closing cam, being
attached to the cam shaft, in turn rotates the pole shaft
through the main link to close the circuit breaker.
In Figure 5-4c the linkage is shown with the circuit
breaker in the closed position before the closing springs
have been recharged. Interference of the trip “D” shaft
with the trip latch prevents the linkage from collapsing,
and the circuit breaker is held closed.
Figure 5-4d shows the circuit breaker in the closed posi-
tion after the closing springs have been recharged. Note
that the spring charging rotates the closing cam by one
half turn. Since the cam surface in contact with the main
link roller is cylindrical in this region, the spring charging
operation does not affect the mechanism linkage.
Since the primary contacts are completely enclosed in
the vacuum interrupter and not adjustable in any way, a
“Slow Close” capability is not provided with VCP-W cir-
cuit breakers.
5-3.4 TRIPPING OPERATION
When the trip “D” shaft is turned either by the trip button
or trip coil, all links return to the original “open” condition
shown in Figure 5-4a.
5-4 CONTROL SCHEMES
There are two basic control schemes for 38kV VCP-W
circuit breakers, one for DC control and one for AC con-
trol voltages (Figure 5-6). There may be different control
voltages or more than one tripping element, but the prin-
cipal mode of operation is as follows:
As soon as the control power is applied, the spring
charging motor automatically starts charging the closing
springs. When the springs are charged, the motor cut off
LS1/bb switch turns the motor off. The circuit breaker
may be closed by making the control switch close
(CS/C) contact. Automatically upon closing of the circuit
breaker, the motor starts charging the closing springs.
The circuit breaker may be tripped any time by making
the control switch trip (CS/T) contact.
Note the position switch (PS1) contact in the spring
release circuit in the scheme. This contact remains
made while the circuit breaker is being levered between
the TEST and CONNECTED positions. Consequently, it
prevents the circuit breaker from closing automatically,
even though the control close contact (CS/C) may have
been made while the circuit breaker is levered to the
CONNECTED position.
The position switch (PS2) contact is in the motor circuit.
It prevents the motor from starting until the fully CON-
NECTED position is reached and the secondary con-
tacts are firmly engaged.
When the CS/C contact is made, the SR closes the cir-
cuit breaker. If the CS/C contact is maintained after the
circuit breaker closes, the Y relay is picked up. The Y/a
contact seals in Y until CS/C is opened. The Y/b contact
opens the SR circuit, so that even though the circuit
breaker would subsequently open, it could not be
reclosed before CS/C was released and remade. This is
the anti-pump function.
5-4.1 TIMING
The opening and closing times for the circuit breakers
vary depending upon the control voltage and the power
rating. Typical values for 38kV VCP-W circuit breakers
are shown in Table 5.1.
5-4.2 SECONDARY DISCONNECTS
The circuit breaker control wiring is arranged to connect
Summary of Contents for Cutler-Hammer VCP-W
Page 2: ......
