Siemens 5-GMI-250 - Maintenance Procedures; Introduction and Maintenance Intervals; Recommended Maintenance and Lubrication; DANGER: Maintenance Safety

Interrupter
/
Operator
Description
Page
20
Figure
38
.
Racking
Mechanism
.
Figure
37
.
Front
View
of
Breaker
.
The
racking
and
trip
-
free
interlocks
provide
four
essential
functions
.
1
.
They
prevent
racking
a
closed
breaker
into
or
out
of
the
switchgear
assembly
.
2
.
They
discharge
the
closing
springs
whenever
the
circuit
breaker
is
inserted
into
,
or
withdrawn
from
,
the
switch
-
gear
.
3
.
They
prevent
insertion
of
a
lower
rated
circuit
breaker
into
a
cubicle
intended
for
a
breaker
of
higher
ratings
.
4
.
They
prevent
closing
of
the
circuit
breaker
unless
it
is
in
either
the
Test
or
Connect
position
.
Racking
Mechanism
Figure
38
shows
the
racking
mechanism
in
the
switchgear
used
to
move
the
circuit
breaker
between
the
Disconnect
,
Test
and
Connected
positions
.
This
mechanism
contains
a
set
of
interface
blocks
that
mate
with
the
bottom
of
the
circuit
breaker
housing
,
and
lock
the
breaker
to
the
racking
mech
-
anism
during
in
and
out
movement
.
A
racking
handle
(
not
shown
)
mates
with
the
threaded
shaft
of
the
racking
mech
-
anism
.
Clockwise
rotation
of
the
crank
moves
the
breaker
into
the
switchgear
,
and
counterclockwise
rotation
removes
it
.
Courtesy of NationalSwitchgear.com