Instruction Book
Effective: March 2007
Page 27
IB6513C80G
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Figure
5-5d
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 DHP-VR
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 type DHP-VR
breakers, one for DC control and one for AC control
(Figure
5-7
).
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 secondary disconnects engage, the
spring charging motor automatically starts charging the
closing springs, 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 (PS1) 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 pre-
vents 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 con-
tact 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, power rating,
environment and test equipment. Differences in timing
are expected between initial factory measurements and
field inspections. Circuit breaker timing can be
measured by service personnel using available
equipment before installation and in conjunction with
regular maintenance periods to assist in tracking the
general health of the breaker. Typical ranges as
observed using nominal control voltages are as follows:
T a b l e 5 . 1
C i r c u i t B r e a k e r T y p e
T i m e i n M i l l i s e c o n d s
Closing Time
(From Initiation of Close
Make)
Opening Time
(Initiation of Trip Signal
to contact break)
Reclosing Time
(Initiation of Trip
Single to contact make)
3 7 . 0 - 6 2 . 2
3 0 - 4 5
1 4 0 - 1 6 5
5-3.2 SECONDARY DISCONNECTS
The breaker control wiring is arranged for drawout
disconnecting by means of a 15 point male plug
arranged to connect to a female receptacle mounted in
the rear of the existing DHP cell. The secondary contact
plug is mounted on a movable bracket on the left side of
the breaker truck (Figures
5-8
and
5-9
)
.
This permits it to
be extended to the rear while the breaker is in the test
position to make with the stationary receptacle in the cell
so that the control circuits are completed. Control wiring
terminates first at terminal blocks mounted at the rear of
the breaker truck, and continues from the terminal
blocks to the male contact plug.
Normally the secondary contacts are held stationary
relative to the breaker chassis. This is accomplished by
a hinged joint in the hand operating rod which acts on the
edge of the lower front truck panel to hold the assembly
in position.
