Siemens GMI Series

Interrupter
/
Operator
Description
on
a
lug
of
the
support
bracket
.
Thus
,
the
torsional
tension
of
the
spring
will
cause
the
cylindrical
assembly
(
5
)
to
be
forcibly
rotated
relative
to
the
support
bracket
.
The
cylindrical
assembly
is
notched
at
the
end
nearest
the
mechanism
side
sheet
with
the
notch
engaging
aspring
pin
(
6
)
driven
into
the
trip
latch
shaft
.
The
notch
has
sufficient
arc
width
to
permit
the
trip
latch
shaft
to
rotate
normally
in
response
to
the
breaker
receiving
a
trip
command
.
The
breaker
jackshaft
(
7
)
is
fitted
with
an
arm
and
track
roller
(
8
)
which
bears
on
the
charging
arm
(
2
)
of
the
cylindrical
assembly
.
Whenever
the
breaker
is
opened
,
the
arm
and
roller
cause
the
charging
arm
to
be
rotated
charging
or
winding
up
the
stored
energy
torsion
spring
.
A
spring
loaded
latch
arm
(
9
)
rises
to
engage
the
latch
face
which
is
an
integral
feature
of
the
cylindrical
assembly
.
The
latch
arm
(
9
)
is
held
in
this
position
by
the
vertical
lever
(
10
)
which
is
pulled
to
the
supporting
position
by
the
electromag
-
net
.
The
vertical
lever
is
pivoted
(
11
)
by
the
electromagnet
(
12
)
against
the
force
developed
by
a
extension
spring
(
13
)
which
constantly
attempts
to
pull
the
vertical
lever
(
10
)
into
a
position
which
releases
the
stored
energy
torsion
spring
.
The
latch
arm
supported
by
the
vertical
lever
retained
in
position
by
the
electromagnet
will
retain
the
stored
energy
state
until
the
electromagnet
senses
a
loss
of
trip
supply
voltage
.
When
the
supply
voltage
falls
to
a
level
30
to
60
percent
cf
nominal
,
the
electromagnet
releases
the
vertical
lever
,
the
latch
arm
descends
and
the
cylindrical
assembly
rotates
disolacing
the
trip
shaft
.
Latching
is
established
at
85
%
nominal
voltage
.
Refer
to
Figure
28
c
.
An
electrolytic
capacitor
resides
across
the
tripping
supply
voltage
connected
through
a
half
wave
rectifier
and
resistor
.
The
rectifier
allows
the
capacitor
to
assume
a
charge
approximating
the
peak
voltage
of
the
AC
tripping
supply
voltage
The
series
resistor
limits
the
magni
-
tude
of
charge
current
flowing
into
the
capacitor
.
The
charged
capacitor
is
then
connected
across
the
breaker
trip
coil
circuit
through
an
external
contact
which
closes
upon
trip
command
.
The
capacitor
size
and
charge
current
magnitude
are
tuned
to
the
inductance
and
resistance
of
the
tripping
solenoid
,
an
RLC
series
circuit
,
to
produce
a
discharge
current
through
the
solenoid
which
emulates
the
magnitude
of
current
and
current
duration
which
the
solenoid
would
experience
if
operated
from
a
DC
tripping
supply
voltage
.
Undervoltage
Release
(
Optional
)
The
undervoltage
release
is
used
for
continuous
monitoring
of
the
tripping
supply
voltage
.
If
the
trip
supply
voltage
falls
significantly
,
the
undervoltage
release
will
provide
for
auto
-
matic
tripping
of
the
breaker
.
Description
of
Operation
-
The
undervoltage
release
consists
of
a
spring
stored
energy
mechanism
,
a
latching
deviceand
an
electromagnet
.
These
elements
are
accommodated
in
a
single
assembly
as
shown
in
Figure
29
.
The
stored
energy
spring
(
1
)
.
spring
charging
arm
(
2
)
and
latch
face
are
arranged
in
a
cylindrical
assembly
concentric
with
the
trip
latch
shaft
(
3
)
.
The
cylindrical
assembly
is
retained
by
the
support
bracket
(
4
)
,
yet
remains
free
to
rotate
.
The
cylindrical
assembly
is
supported
by
the
trip
latch
shaft
which
rotates
freely
on
the
trip
shaft
supported
by
needle
bearings
.
The
stored
energy
torsion
spring
(
1
}
has
one
tail
bearing
on
a
lug
fixed
to
the
cylindrical
assembly
,
and
an
opposite
tail
fixed
Interlocks
There
are
two
interlocks
which
prevent
certain
unsafe
operat
-
ing
conditions
.
They
are
the
rating
interlock
and
the
trip
-
free
interlock
.
Q
)
|
Q
6
ROLL
PIN
IN
LATCH
SHAFT
ASSY
§
/
E
/
LATCH
SHAFT
ASSY
1
HI
3
LATCH
SHAFT
ASSY
9
TT
mf
13
!
i
is
10
J
2
7
JACKSHAFT
CENTER
LINE
5
1
m
JACKSHAFT
mi
8
4
i
Figure
29
:
Undervoltage
Trip
Option
19
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