Siemens GMI Series

Interrupter
/
Operator
Description
handling
of
the
breaker
when
all
circuit
breakers
are
located
in
the
lower
cells
.
Once
the
circuit
breaker
is
racked
out
of
the
switchgear
,
the
unit
can
be
pulled
using
the
handles
on
the
front
of
the
breaker
.
The
breaker
will
roll
on
its
bottom
four
wheels
.
On
indoor
and
Shelter
-
Clad
switchgear
with
circuit
breakers
located
in
the
lower
cell
,
the
circuit
breaker
is
easily
rolled
out
of
the
switchgear
by
a
single
person
.
When
circuit
breakers
are
located
in
the
upper
cells
,
handling
of
the
circuit
breakers
requires
the
use
of
a
hoist
or
crane
.
These
lifting
devices
are
also
required
for
removal
of
the
lower
circuit
breaker
of
non
walk
-
in
type
outdoor
switchgear
.
Racking
Mechanism
Figure
31
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
mechanism
during
in
and
out
movement
.
A
racking
handle
(
not
shown
)
mates
with
the
threaded
shaft
of
the
racking
mechanism
.
Clockwise
rotation
of
the
crank
moves
the
breaker
into
the
switchgear
,
and
counterclockwise
rotation
removes
it
.
The
racking
and
trip
-
free
interlocks
provide
several
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withdrawn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
switchgear
.
3
.
They
prevent
closing
of
the
circuit
breaker
unless
it
is
in
either
the
Test
or
Connect
positions
.
The
rating
interlock
prevents
insertion
of
a
lower
rated
circuit
breaker
into
a
cubicle
intended
for
a
breaker
of
higher
ratings
.
Trip
Free
Interlock
-
Figure
30
shows
the
devices
providing
the
trip
-
free
interlock
function
.
The
purpose
of
the
trip
-
free
interlock
is
to
hold
the
circuit
breaker
operating
mechanism
mechanically
and
electrically
trip
free
whenever
the
breaker
is
between
the
Test
and
Connected
.
positions
within
the
switch
-
gear
enclosure
.
This
interlock
ensures
that
the
circuit
breaker
primary
contacts
can
only
be
closed
when
in
the
Connect
position
,
or
the
Test
position
,
or
out
of
the
switchgear
cell
.
Rating
Interlock
-
Figure
30
shows
the
rating
interlock
inter
-
ference
plates
mounted
on
the
circuit
breaker
frame
.
The
breaker
interference
plates
are
complemented
by
matching
plates
located
in
the
cubicle
.
The
interference
plates
(
rating
interlocks
)
test
the
breaker
voltage
,
continuous
current
,
interrupting
and
momentary
rat
-
ings
and
will
not
allow
breaker
insertion
unless
they
match
or
exceed
the
cell
rating
.
Circuit
Breaker
Frame
The
frame
of
the
GMI
circuit
breaker
contains
several
important
devices
and
features
deserving
of
special
attention
.
These
are
the
ground
disconnect
,
the
four
racking
wheels
and
four
handling
wheels
.
Ground
Disconnect
-
Figure
30
shows
the
ground
disconnect
contact
mounted
at
the
bottom
of
the
circuit
breaker
.
The
spring
loaded
fingers
of
the
disconnect
contact
engage
the
ground
bar
(
Figure
31
)
at
the
bottom
of
the
switchgear
assembly
.
The
ground
bar
is
to
the
right
of
the
racking
mechanism
,
shown
at
the
bottom
center
of
the
switchgear
.
Circuit
Breaker
Handling
Wheels
-
The
GMI
circuit
breaker
is
designed
for
easy
movement
into
and
out
of
the
metal
-
clad
switchgear
assembly
.
A
section
of
indoor
or
Shelter
-
Clad
switchgear
does
not
require
a
transfer
truck
or
lifting
truck
for
Figure
30
:
Breaker
Interlocks
and
Ground
Disconnect
.
Figure
31
:
Racking
Mechanism
and
Floor
Interlocks
.
20
Courtesy of NationalSwitchgear.com