GEK-721 01, Low
V oltoge
Swifchgeor
a9
.2'
.tr
n
FlG. l9
(0625E0376)
Rqckoui
mechonism for AK breokers
RACKOUT
MECHANISM
OPERATION
AK BREAKERS
Part numbers in Figure 19 refer to
part
numbers on
Drawing
0673D0500
Sheet 627 Groups 05
or
06.
The rackout mechanism is operated
by
pushing
the
handle onto the
end of
the
jackscrew
shaft
and
rotating
the handle. Clockwise
rotation moves
the breaker
into
the
house
and
counter-clockwise
rotation moves the
breaker
out. Approximately 17 turns of the handle will
move the
breaker
from the DISCONNECTED
to the CONNECTED
position.
To
properly
engage the handle
with
the
jackscrew
shaft, the slot
in the end of the handle should align
with the
pin
through the
shaft. When the
pin
is so
aligned,
the
square hole in the handle will be engaged with the square
drive end of
the
shaft.
The rackout mechanism
is
interlocked so that the circuit
breaker must be
open before the operating
handle can be
inserted.
When the breaker is
closed,
an interlock link
operated
by the
breaker
cross
bar
blocks
the interlock
link-
age on the rackout mechanism
and
prevents
the tube
(63)
from
being
moved
back to fully
expose
the square shaft
end.
The
pin (105)
in the
jackscrew
shaft
engages in a slot
in the
tube. This slot
prevents
rotation of the
shaft
and
also assures
that the interlock linkage must be moved
through
a
prescribed
distance
before operation
of the
mech-
24
anism is
possible.
When the tube is
pushed
back so that it
will clear the
pin,
a cam surface on the interlock slide
(46)
engages a trip link on the side of the breaker and holds
it
trip free
as
long as the handle is
engaged
or the interlock
tube
is in the retracted
position.
There is also a stationary
cam
in the
house which
holds
the breaker trip free as
it is
moved
between the CON-
NECTED
and
TEST
positions.
This stationary cam comes
into operation before the
primary
disconnects have
parted
and is operable whether or
not
the rackout
handle is en-
gaged.
The
breaker thus cannot be closed when
it is be-
tween the
TEST
and the CONNECTED
positions.
From
the TEST to the
DISCONNECTED
position,
the breaker
can be closed when the rackout handle is disengaged
and
the
pin
in the
jackscrew
is
aligned
with the slot in the inter-
lock tube
so
that
the interlock linkaee
is in the reset
position.
An indicator
(75)
which
is visible through
an opening
in the front of the door
shows the
position
of the breaker in
the
house. The TEST
position
is
reached when
the line on the
indicator
label
marked
TEST is aligned with
the stationary
line
on the indicator
housing. In this
position,
the breaker
can
be operated
when the
pin (105)
and
the slot in the
interlock tube are aligned
and
the rackout handle is dis-
engaged. The secondary
control
power
disconnects
are en-
gaged
and the
primary
power
disconnects are open in
this
position.
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