Siemens GM-SG

Circuit
Breaker Positions
Circuit
Breaker
Cell
Preparation
The circuit breaker cell contains the
positioning
,
interlocking
and
operating
devices described
below
and shown
in
Figures
35
and
37
.
These devices
must
be checked
for
placement
and
freedom of
operation
.
A
WARNING
Hazardous
voltages
.
Can
cause
death
,
serious
injury
and
property
damage
.
Do
not
insert
a
circuit breaker into
a
cell
intended
for
a
circuit
breaker
with
ratings
above
those
of
the circuit breaker
being
inserted
.
Verify
that circuit
breakers and
cubicles
have
appropriate
ratings
and
properly
located
interference
blocking
plates
and
angles
before
attempting
to
insert
a
circuit breaker
.
Circuit
Breaker
Racking
Mechanism
The
circuit
breaker
racking
mechanism is
centered
below
the
circuit breaker
.
It
functions
in
conjunction
with
the
trip
-
free
interlock
on
the circuit breaker
,
to
hold the circuit breaker
trip
-
free
between
positions
.
Three
positions
are
provided
:
DISCONNECT
,
TEST
,
and
CONNECT
.
The interlock
will
allow
a
2000
A
or
3000
A
circuit
breaker
to enter
a
1200
A
cell
,
provided
the
voltage
,
interrupting
,
and continuous
current
ratings
equal
or
exceed the
ratings
of
the cell
.
The
coordinating
interference
plate
on
the circuit
breaker is shown
in
Figure
36
.
m
BUS
M
QJ
i
*
[
G
X
m
Qh
HI
3
A
t
id
E
m
[
£
m
A
.
Interference
blocking
plate
(
rating
interlock
)
B
.
Racking
mechanism
C
.
Ground
bar
D
.
Guide
rails
E
.
Trip
free
and
racking
interlock
padlock provisions
F
.
MOC
switch
operator
G
.
MOC
switch terminals
H
.
TOC
switch terminals
I
.
Shutter
operating linkage
J
.
Shutter
(
behind barrier
)
K
.
CT
barrier
L
Secondary
disconnect
Figure
35
.
Circuit
Breaker
Compartment
(
MOC / TOC
Switch
Cover
Removed
for
Photo
)
Interference
Blocking
Plate
(
Rating
Interlock
)
This
plate
is
mounted
vertically
on
the bottom
of
the
cell
to
allow
only
the
properly
rated circuit breaker into the
designated
cell
(
e
.
g
.
,
a
1200
A
circuit breaker
to enter
a
1200
A
cell
,
or a
2000
A
circuit breaker
to enter
a
2000
A
cell
)
,
depending
on
the
voltage
,
interrupting
,
and
continuous
current
ratings
.
Normally
the cubicle and
circuit breaker
rating
plate
combinations
will
be identical
.
Figure
36
,
interlocks
on
Bottom
of Circuit
Breaker
Secondary
Disconnect
The
secondary
disconnect contains
all the
electrical
control
circuit connections
for
the
circuit breaker
.
It
mates
with
the
secondary
disconnect block
on
the
circuit breaker
.
The circuit breaker
contacts
slide
against
the cell
contact
strips
.
The
secondary
contacts
are
automatically
mated
in
the
TEST
and
CONNECT
positions
.
38
Courtesy of NationalSwitchgear.com