Siemens 5-GMI-250 - Page 15

Interrupter
/
Operator
Description
4
Page
12
The
tripping
spring
is
connected
to
the
jack
shaft
.
When
the
circuit
breaker
closes
,
rotation
of
the
jack
shaft
causes
the
tripping
spring
push
rod
to
compress
and
charge
the
trip
-
ping
spring
.
Consequently
,
the
tripping
spring
is
automat
-
ically
charged
whenever
breaker
contacts
are
closed
.
Trip
Free
Operation
The
GMI
circuit
breaker
is
mechanically
and
electrically
trip
free
.
This
important
function
enables
the
breaker
to
be
tripped
before
,
after
or
during
a
closing
operation
.
When
-
ever
the
circuit
breaker
trip
shaft
is
moved
as
the
result
of
manual
or
electrical
signals
or
mechanical
interlocks
,
a
)
a
closed
breaker
will
open
,
b
)
a
breaker
in
the
process
of
closing
will
not
complete
the
close
operation
and
will
remain
open
,
or
c
)
an
open
breaker
will
not
be
able
to
be
closed
.
Dashpot
Assembly
GMI
circuit
breakers
are
equipped
with
a
dashpot
assembly
to
smooth
the
final
motion
of
an
opening
operation
.
Figure
20
illustrates
major
components
of
this
assembly
.
The
dash
-
pot
is
a
piston
,
with
two
internal
Teflon
sealing
rings
moving
inside
a
cylinder
vented
to
ambient
air
.
Up
and
down
motion
of
the
piston
creates
an
opposing
force
,
controlling
the
opening
speed
of
the
circuit
breaker
.
The
dashpot
push
rod
is
connected
to
the
jack
shaft
by
a
crank
linkage
.
by
charging
status
of
the
closing
springs
or
position
of
the
drive
cam
(
20
)
.
Rapid
Auto
-
Reclosing
Mode
The
closing
springs
are
automatically
recharged
by
the
motor
driven
operating
mechanism
when
the
breaker
has
closed
.
The
operating
mechanism
is
capable
of
the
open
-
close
-
open
duty
cycle
required
for
rapid
auto
-
reclosing
.
A
trip
latch
check
switch
prevents
release
of
the
closing
springs
if
the
trip
hatchet
(
99
)
is
not
in
its
reset
position
.
This
ensures
the
mechanism
does
not
operate
trip
free
on
an
instantaneous
reclosure
.
Closing
and
Tripping
Springs
The
stored
energy
assembly
consists
of
two
dual
closing
springs
and
a
single
tripping
spring
.
Figure
19
shows
the
three
springs
and
their
linkages
to
the
charging
devices
.
The
two
closing
springs
are
connected
to
crank
arms
mounted
on
the
rotating
main
cam
shaft
.
The
closing
springs
are
extended
,
and
charged
,
by
rotation
of
the
crank
arms
connected
to
the
movable
ends
of
the
springs
.
The
fixed
ends
of
these
springs
are
attached
to
a
support
arm
,
which
in
turn
is
bolted
to
the
structure
of
the
circuit
breaker
.
4
i
Figure
20
.
Dashpot
Assembly
.
Figure
19
.
Closing
and
Tripping
Springs
.
Courtesy of NationalSwitchgear.com