Siemens GMI Series

Interrupter
/
Operator
Description
Primary
Disconnects
-
Figure
12
is
a
side view
of
the
circuit
breaker
with
a
side
phase
barrier removed
to
show details
of
the
primary
disconnects
.
Each circuit breaker has three
upper
and three lower
primary
disconnects
.
Upper
primary
discon
-
nects
are
connected
to
the
stationary
contacts
of
the
vacuum
interrupters
,
and the lower
primary
disconnects
to
the movable
contacts
.
Each disconnect
arm
has
a
set
of
multiple
spring
loaded
fingers
that
mate
with
bus bars
in
the metal
-
clad
switchgear
.
The
number
of
fingers
in
the disconnect
assembly
varies
with
the continuous
and
/
or
momentary
rating
of
the
circuit breaker
.
There
are
three
insulating
push
rods
.
Each
push
rod
connects
the
movable
contact
of
one
of
the
vacuum
interrupters
to
the
jack
shaft
driven
by
the
closing
and
tripping
mechanism
.
Flexible
connectors
ensure secure
electrical
connections
be
-
tween
the
movable
contacts
of
each
interrupter
and
its bottom
primary
disconnect
.
Phase Barriers
-
Phase
barrier
configurations
vary
among
GMI
breakers
depending
on
voltage
and continuous
current
ratings
.
Figure
13
is
a rear
view
of
a
circuit breaker that shows
the
two
outer
(
phase
to
ground
)
insulating
barriers and
two
interphase
barriers
.
The
interphase
barriers
are
not
provided
on
all
circuit
breaker
ratings
.
These
four
plates
of
glass polyester
insulating
material
are
attached
to
the circuit breaker and
provide
suit
-
able
electrical insulation between
the
vacuum
interrupter
pri
-
mary
circuits
and
the
housing
.
Stored
Energy
Operating
Mechanism
The stored
energy
operating
mechanism
of
the
GMI
circuit
breaker is
an
integrated
arrangement
of
springs
,
solenoids
and mechanical
devices
designed
to
provide
a
number
of
critical
functions
.
The
energy necessary
to
close and
open
the
contacts
of
the
vacuum
interrupters
is stored
in
powerful
tripping
and
closing
springs
.
These
springs
are
normally
charged
automatically
,
but
there
are
provisions
for
manual
charging
.
The
operating
mechanism that controls
charging
,
closing
and
tripping
functions
is
fully
trip
-
free
,
i
.
e
.
,
spring
charging
does
not
automatically change
the
position
of
the
primary
contacts
,
and
the
closing
function
may
be overridden
by
the
tripping
function
at
any
time
.
Note
:
Two
different
latch
systems
have been used
in
GMI
circuit breakers
,
with
changeover
from
one
design
to
the other
occurring
in
mid
-
1991
.
This instruction manual describes both
designs
.
Pages
10
-
11
describe
the
operation
of
the mechanism
used
beginning
in
approximately
mid
-
1991
.
Pages
12
-
13
describe the
operation
of
the
mechanism
used
from
1989
until
approximately
mid
-
1991
.
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Figure
12
:
Upper
and Lower
Primary
Disconnects
.
Figure
13
:
Breaker
with
Interphase
and
Outerphase
Barriers
.
9
Courtesy of NationalSwitchgear.com