Siemens 5-GMI-250 - Page 20

Interrupter
/
Operator
Description
Page
17
Figure
30
.
Circuit
Breaker
Limit
Switches
.
Interlocks
Circuit
Breaker Frame
There
are
two
interlocks
which
prevent
certain
unsafe
operating
conditions
.
They
are
the
rating
interlock and the
trip
-
free
interlock
.
Trip
Free
Interlock
Figure
33
shows
the
devices
providing
the
trip
-
free
inter
-
lock
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
switchgear
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
34
shows
the
rating
interlock
interference
plates
mounted
on
the
circuit
breaker
frame
.
The breaker
inter
-
ference
plates
are
complemented
by
matching
plates
lo
-
cated
in
the
cubicle
.
The
interference
plates
(
rating
interlocks
)
test
the breaker
voltage
,
continuous
current
,
interrupting
,
and
momentary
ratings
and
will
not
allow
breaker
insertion
unless
they
match
or
exceed
the
cell
rating
.
The
frame
of
the
GMI
circuit
breaker contains
several
im
-
portant
devices and
features
deserving
of
special
attention
.
These
are
the
ground
disconnect
,
the
four
racking
wheels
,
and
four
handling
wheels
.
Ground
Disconnect
Figure
35
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
,
shown
in
Figure
36
,
at
the bottom
of
the
switchgear
as
-
sembly
.
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
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
shown
in
Figure
37
.
The
breaker
will
roll
on
its
bottom
four
wheels
.
Courtesy of NationalSwitchgear.com