Siemens GM-SG

Circuit
Breaker Positions
Racking
Access
Interlock
The
racking
interlock slide
(
Figure
47
,
item
62
)
has
provisions
for
three
padlocks
to
prevent
engagement
of
the
racking
crank
to
the
racking
screw
.
This allows
locking
of
the circuit breaker
in
DISCONNECT
,
TEST
,
or
CONNECT
positions
.
Key
interlocking
(
Figure
47
,
item
42
)
can
be
provided
for
racking
sequence
interlocking
of
dummy
elements
,
etc
.
When
the
key
interlock
bolt
(
on
key
interlock
,
item
42
)
is extended
,
the
racking
interlock slide
(
item
62
)
is held
in
place
,
preventing
access
to
the
racking
screw
,
thus
preventing racking
.
When locked
in
the
DISCONNECT
position
,
the circuit
breaker
or
dummy
element
can
be removed
for
servicing
.
Trip
-
Free
Interlock
The
trip
-
free
interlock slide
prevents
a
circuit breaker
from
being
closed between the
TEST
and
CONNECT
positions
by maintaining
a
mechanical and electrical
trip
-
free
condition
.
As
the circuit breaker
moves
between the
TEST
and
CONNECT
positions
,
the
spring
dump
/
trip
-
free
roller
engages
the
spring
dump
/
trip
-
free
cam
profile
rail
of
the
racking
device
.
As
the roller travels
along
the
profile
of
rail between
positions
,
the roller
activates
the
trip
linkage
which holds the
circuit
breaker
in
a
mechanically
trip
-
free
condition
.
(
Figure
48
)
.
In
order
to
lock the circuit breaker
trip
-
free
in
either the
TEST
or
CONNECT
positions
,
the circuit breaker
must
be
opened
and the
trip
-
free
interlock slide
assembly
pushed
forward
to
lift
the
trip
-
free
roller
on
the
circuit
breaker
.
This
position permits
the
use
of
a
key
interlock
(
Figure
47
,
item
41
)
or
padlocks
(
up
to
3
)
to
maintain
the mechanism
in
trip
-
free
position
.
The circuit breaker
can
be removed
for
servicing
while interlocked
in
the
trip
-
free
position
.
The interlock
can
be
tested
by racking
the
circuit
breaker
to
a
position
between the
TEST
and
CONNECT
position
with
the
closing springs charged
.
Activating
the
"
close
"
function
manually
will
cause
the
springs
to
discharge
and the interlock should
prevent
the circuit
breaker
from
closing
.
Activating
the
"
close
"
function
electrically
(
such
as
by using
the control switch
)
should
cause no
operation
.
This is
also
true
when the
circuit
breaker
is
in
either
the
TEST
or
CONNECT
positions
and
the
trip
-
free
interlock slide is
pushed
forward
and
key
interlocked
or
padlocked
.
The circuit breaker
will
operated trip
-
free
when
closing
is
attempted
.
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Trip
-
free
padlock
L
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provisions
(
Note
2
)
Racking
padlock
provisions
(
Note
1
)
o
o
62
60
Without
Key
Interlocks
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With
Key
Interlocks
41
Note
1
:
Racking
padlock provisions
-
when
padlocked
,
prevents
racking
of
circuit breaker
,
test
device
,
or
dummy
breaker element
.
Suitable for
up
to
three
padlocks
with
up
to
3
/
8
'
(
or
10
mm
)
diameter shackle
.
Spring
Discharge
Function
The
closing spring discharge
function
prevents
the
insertion
or
removal
of
a
circuit breaker
with
a
charged
mechanism
.
The
closing spring discharge
function
is
achieved
as
the
spring
/
dump
/
trip
free
roller
of
the
circuit breaker
follows
the
cam
profile
of
the
racking
mechanism rail
.
As
the
spring
dump
/
trip
free
roller
of
the circuit breaker rides the rail
,
the
spring
dump
/
trip
free
roller
assembly
of
the circuit breaker is driven
upward
,
activating
the
spring
dump
linkage
located
inside the circuit breaker enclosure
,
releasing
the
closing springs
while the
circuit
breaker
is
held
trip
-
free
.
This
discharges
the
closing springs
without
closing
the
circuit breaker
primary
contacts
.
Note
2
:
Trip
-
free
padlock provisions
-
when
padlocked
,
prevents
closing
of
circuit breaker
or
test
device
.
Suitable for
up
to
three
padlocks
with
up
to
3
/
8
'
(
or
10
mm
)
diameter shackle
.
Figure
47
.
Racking
Mechanism
and
Interlocks
Disconnect
Position
Connect
Position
Test
Position
V
Trip
Free
L
y
;
?
Q
[
3
toT
Disconnect
Position
of
Breaker
a
Trip
Free
Roller
Assembly
on
Breaker
Trip
Free
Interlock
Slide
Connect
Position
of
Breaker
Test
Position
of
Breaker
Figure
48
.
Trip
Free
Interlock Positions
(
Viewed
From
Right
Side
of Circuit
Breaker
)
44
Courtesy of NationalSwitchgear.com