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Instruction Book
Page 30
Effective: February 2007
5-3.2 CHARGING
Figure 5-7 is a schematic view of the spring charging
parts of the stored energy mechanism.
The major component of the mechanism is a cam shaft
assembly which consists of a drive shaft to which are
attached two closing spring cranks (one on each end),
the closing cam, drive plates, and a free-wheeling
ratchet wheel. The ratchet wheel is actuated by an
oscillating mechanism driven by the motor eccentric. As
the ratchet wheel rotates, it pushes the drive plates
which in turn rotate the closing spring cranks and the
closing cam with it.
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 closing
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
charging 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 5-6 shows the position of the closing cam and
tripping linkage. Note that in Figure 5-6a in which the
breaker is open and the closing springs are discharged,
the trip "D" shaft and trip latch are in the unlatched
position.
Once charged, the closing springs can be released to
close the 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 breaker.
In Figure 5-6c the linkage is shown with the 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
breaker is held closed.
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Figure 5-6d shows the breaker in the closed position
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-WR
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 5-6a.
5-3.5 TRIP FREE OPERATION
When the manual trip button is held depressed, any
attempt to close the breaker results in the closing
springs discharging without any movement of the pole
shaft or vacuum interrupter stem.
5-4 CONTROL SCHEMES
There are two basic control schemes for each series of
Type VCP-WR breakers, one for DC control and one for
AC control voltages (Figure 6-2). The schematic
drawing numbers associated with VCP-WR breakers
are as follows:
VCP-1 8WR
(DC Control) — 8795C30H10
(AC Control) — 8795C30H1 1
VCP-20WR
(DC Control) — 6467C33H1 1
and
VCP-29WR
(AC Control) — 6467C33H12
There may be different control voltages or more than
one tripping element, but the principal mode of
operation is as follows:
As soon as the control power is applied, the spring
charging motor automatically starts charging the closing
spring. When the springs are charged, the motor cut off
LS1/bb switch turns the motor off. The breaker may be
closed by making the control switch close (CS/C) con-
tact. Automatically upon closing of the breaker, the
motor starts charging the closing springs. The breaker
may be tripped any time by making the control switch
(CS/T) contacts.
I.B. 8295A61H07
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