Instruction
Book
Page 32
IB131009EN
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 W-VAC and
W-VACW breakers.
5-2.4 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
5-5a
).
5-2.5 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.
5-3
CONTROL SCHEME
There are two basic control schemes for all the circuit-
breakers, one for DC control and one for AC control
voltages or more than one tripping element, but the prin-
cipal mode of operation is as follows:
As soon as the secondary disconnects engage, the
spring charging motor automatically starts charging the
closing spring, provided control power is available.
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) contact.
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.
Note the position switch (PS) contact in the spring
release circuit in the scheme. This contact remains
made while the breaker is being levered between the
TEST and CONNECTED positions. Consequently, it
prevents the breaker from closing automatically, even
though the control switch close contact may have been
made while the breaker is levered to the CONNECTED
position.
When the CS/C contact is made, the SR closes the
breaker. If the CS/C contact is maintained after the
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 breaker would
subsequently open, it could not be reclosed before
CS/C was released and remade. This is the anti-pump
function.
5-3.1 TIMING
The opening and closing times for the circuit breakers
vary depending upon the control voltage and the power
rating. However, the typical values are as follows in
Table
5.1
.
Table 5.1 Typical Opening and Closing Times
Event
Time in Milliseconds
Closing Time
(From Initiation of Close
Signal to Contact Make)
75
Opening Time
(Initiation of Trip Signal
to Contact Break)
45
Reclosing Time
(Initiation of Trip Signal
to Contact Make)
190
5-3.2 SECONDARY DISCONNECTS
The drawout breaker control wiring is arranged to con-
nect a 25 point male plug as standard with a corre-
sponding female plug mounted in the switchgear com-
partment. An additional 25 point plug is optional and can
be supplied when an additional auxiliary switch beyond
the standard is supplied. The fixed circuit breaker uti-
lizes a similar fixed secondary connection scheme.
The drawout breaker plugs are mounted in small enclo-
sure located on the upper left front portion of the basic
breaker element (Figure
3-4
)
.
This male plug automati-
cally connects or disconnects with a structure mounted
female plug as the breaker is racked into or out of the
connected position.
If the drawout breaker is being used in a flush mounted
configuration, the breaker must be moved to the discon-
nected position for testing. It is recommended that a test
cable be used to connect the female and male sec-
ondary contacts when in the disconnected position. The
structure mounted secondary contact blocks are perma-
nently mounted and cannot be moved out for direct con-
nection with the breaker mounted secondary contacts.
The behind the door drawout design utilizes movable
carriage mounted female plugs in the structure. A
"TEST" position is available within the structure. Once
the breaker is racked out to the test position, the struc-
ture mounted secondary plug carriage can be manually
unlatched, and pulled forward until the female plugs
mate with the breaker mounted male plugs. To disen-
gage the secondary plugs from the "TEST" position,
simply push the carriage to the rear.
Summary of Contents for 120W-VAC16
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