Siemens GM-SG

Circuit
Breaker Positions
Racking
Crank
Engagement
Procedure
A
crank
for
racking
the drawout circuit breaker is
provided
as a
standard
accessory
.
Racking
of
a
circuit breaker
can
be
accomplished
with
the
circuit
breaker
compartment
front
door
open
or
through
a
small
opening
(
or
window
)
in
the
front
door
,
with
the door closed
.
The
racking
crank consists
of
an
offset
handle
with
a
custom
socket
assembly
welded
to
the
opposite
end
.
The socket end
of
the crank is
designed
to
engage
the
square
shoulder
of
the
racking
mechanism
shaft
and
remain
engaged
during racking
by
means
of
two
spring
plungers
located
180
degrees
from
each other
.
The
spring plungers
operate
in
a
manner
similar
to
the
retainers
on an
ordinary
mechanic
'
s
socket wrench
.
The
portion
of
the
racking
mechanism
shaft
which
is
visible is
cylindrical
,
and
the
square
shoulder
of
the
racking
mechanism
shaft
is hidden
by
a
shroud
until
the
engagement
procedure
starts
.
The
square
socket
end
of
the crank
will
only
engage
the
square
portion
of
the
shaft
if
it
is
aligned properly
.
The
suggested
procedure
to
engage
the
racking
mechanism is
as
follows
:
1
.
The circuit breaker
must
be
open
.
(
The
racking
shroud
cannot
be moved
if
the circuit breaker is closed
)
.
2
.
Hold the socket end
of
the crank
in
one
hand and the
crank handle
in
the other hand
.
Refer
to
Figure
44
.
3
.
Place the socket
over
the end
of
the
racking
mechanism
shaft
.
Align
the
spring plunger
of
the
socket
with
the
shoulder
on
the
racking
mechanism
shaft
.
Note
:
If
the socket is
not
aligned
,
the socket
will
not
be able
to
engage
.
The socket
(
square
)
must
be
aligned
with
the
square
shoulder
of
the
racking
mechanism
shaft
.
4
.
Once
alignment
is achieved
,
firmly
push
the crank
and socket
assembly
toward the
racking
mechanism
.
5
.
When
properly engaged
,
the crank should
remain
connected
to
the
racking
mechanism
,
due
to
the
spring plungers
.
If
the crank does
not
remain
in
position
,
adjust
the
spring plungers
clockwise
one
-
half
turn
.
This
will
increase the
contact
pressure
of
the
spring plunger
.
6
.
To
remove
the crank
,
simply
pull
the
assembly
off of
the
racking
mechanism
shaft
.
Note
:
If
the
effort
to
rack the circuit breaker increases
considerably during racking
,
or
if
turning
of
the
racking
crank
requires
excessive
force
,
stop
racking immediately
.
Do
not
try
to
"
force
"
the
racking
crank
to rotate
,
or
parts
of
the
circuit
breaker
or
racking
mechanism could be
damaged
.
Determine
the
source
of
the
problem
and
correct
it
before
continuing
with
the
racking
.
Socket
Assembly
Hand
Position
Hand
Position
©
(
Spring
Plunger
Crank
Rotated
for
Clarity
Spring
Plunger
Racking
Mechanism
Shaft
-
rW
-
=
=
=
=
Articulated Joint
Shoulder
Portion
of
Shaft
Custom
Socket
Spring
Plunger
Figure
44
.
Racking
Crank
Engagement
Procedure
.
Circuit
Breaker
Racking
When
inserting
a
circuit breaker into
a
cell
,
be
sure
that the
racking
mechanism is
in
the disconnect
position
.
In
this
position
,
the
racking
position
indicator should show
a
green
square
with
the letter
"
D
"
for
DISCONNECT
position
.
Important
:
Failure
to
follow
instructions
may
result
in
damage
to
equipment
.
Return
racking
mechanism
to
the
DISCONNECT
position
before
inserting
circuit breaker
.
Figure
45
.
Racking
Mechanism
with
Racking
Block
.
42
Courtesy of NationalSwitchgear.com