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Power Circuit Breakers,
GEK-731O
gage
the stationary bar in the equipment enclosure.
The
opening
of
these
fingers against the force
of
the
springswill
cause
a
noticeablyhigher load require-
ment
in the
racking
effort.
This
will very
quickly
fali
off to
a
lesser force
requirement to the
end of
travel, at
which point
a
stop
will
be encountered.
About
three
handle
turns will
be
required
between
the peak force requirement and reaching the
stop
which
ends
the
movement.
Upon
reaching
the
stop,
the
handle should
be
removed without any
rever-
sal
of the
handle
motion.
Approximately
24
turns
on the handle are required
for
the
complete rack-
ing cycle.
15. The
first
time the breaker is
introduced into
the enclosure,
it
should
be
completely withdrawn
and
the
marks
of
the
disconnect
fiagers on
the
grease
on
the stationary
bars
examined.
These
tracks marks should indicate
no
less than 1/4-inch
engagement.
The maximum
amount
that
can
be
attained
is
g/16-inctr.
BREAKER
WITHDRAWAL
1.
Trip
the breaker open, hold
in
the
trip
but-
ton,
and
move the
sliding
cover
in
the
escutcheon
aside
to the right.
2.
Engage
the racking
handle
and crank
in
a
counterclockwise
direction.
3.
ApproximateLy 24
turns
of
the
handle wiII
complete
the racking-out
operation and
bring
the
breaker to the disconnected
position.
This
will
be
shown
on
the
indicator
in
the compartment
and
will
be evident
to
the person
operating
the
mechanism
because
a
stop
will
be encountered beyond which
no
further
movement can be
made.
Towards the
end
of
the racking cycle, the "closing spring interlock"
willbe
activated. This willcause theclosing spring
to discharge,
but
will
not close the breaker.
4.
To withdraw the
breaker completely,
open the
latches
onthe
ends
ofthe
rails,
and
pull thebreaker
out
of the
compartment. The breaker may
now be
Iifted off
the
rails
by the
lifting
device.
STATIONARY
BREAKERS
Stationary breakers
are
intended
for
separate
mounting on
a
framework
or
switchboard
panel, or
in
an enclosure
of
the
customerts own design
and
construction.
They
are
the same
breaker unit
as
the
drawout type; however,
they do not have
the
drawout features, namely, the racking
mechanism
and
automatic disconnects and
interlocks.
Careful consideration
should
be given
to the se-
lection of a location
for
mounting
stationary break-
ers.
They should
be
situated so that they can
be
easily reached
for
operation and maintenance,
with
enough
surrounding
free
space
so that working
in
the
area is not troublesome.
If it is
possible,
the
Iocation chosen should
bedry
andclean andnot sub-
ject to extreme variations of temperature.
Mounting
the breaker
involves
bolting the frame
of the breaker
to
its
supporting
structure within
the
switchboard
or
enclosure, making power
connec-
tions
tothebreaker
studs, andmaking
control
power
connections
to
the
breaker terminal board
and
arx-
iliary
switch
terminals,
if
these
are
required.
Four
mountingholes
are required
forthe
hardware which
fastens the
frame to
its
support.
These mounting holes must
all
be
in
the
same
vertical plane. If they
are
not, strain
may
be
im-
posed
on the breaker structure which
could
ad-
versely
a-ffect
the operation of the
breaker.
The
ouiline
drawing which
is
furnished
with
the
breaker
gives
information
on
preparing a mounting
structure
and a
cover
or
door suitable for preventing
access
to live parts of the breaker.
Another
requirement of the supporting structure
for
the breaker
is
that
it
be
rigid
enough
to with-
stand
the forces that result
from
high
momentary
and
short-circuit
currents to which thebreaker
may
be
subjected.
Connectingbus
or
cable
must also
be
supportedadequately
to resist
these
forces.
points
of
support
for
buswork
or
cable must be
close
enough
to
the
breaker so that no appreciable strain
is
imposed on the
breaker's
studs.
Manual
breakers must be located so that clear-
ance is
provided
for
the sweep
of the
handle when
it
is
operated. This
requirement
will
be
11
inches
to
the
right
from
the centerline
of
the
breaker, or
2-l/2
arches beyond the
right
edge
of
the breaker
frame.
Since
eachupper
studof thebreaker
is
composed
of
two separate members, the connections
to
the
stud
must provide a solid connection across the
two
parallel
stud
members,
as
well
as an
external
con-
nection.
All
stationary breakers
will
be
shipped
with
connector bars already fastened to both
upper
and
lower studs.
These
bars
will
accommodate
cable connectors
or
busbars.
If
an external bar
connects across both halves
of the upper studs,
the
connectorb:rrs may bedispensed
with. hthis
case,
the end
of the
connecting bus
should
extend
in
to-
wards the breaker base
no
more than 5/8-inctr be-
yond
the centerline of the fastener
hole.
Control
connections
on stationary breakers
are
made
to
a
terminal
board
located
in
the
upper
left
frontarea of thebreaker (front view).
The
terminal
board
may have
6,
10
or
14
points.
This
will
be
governedby
the
requirements
of
the control scheme.
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