Siemens 81000 90H35

Description
Page
2
The
clearance
between
the
cup
(
3.3
)
and
the
nut
(
3.4
)
in
the
ON
switching
position
allows
the
magnetic
drive
to
accelerate
during
opening
operations
.
A
compression
spring
(
4.7
)
is
positioned
between
the
drive
lever
(
3.1
)
and
the
vacuum
interrupter
(
4.1
)
.
Description
of
Operation
(
Refer
to
Figure
1
.
)
The
drive
lever
(
3.1
)
forms
an
angle
,
with
point
A
as
the
fulcrum
.
When
the
magnet
is
not
energized
,
the
lever
is
held
in
the
OFF
position
by
the
compression
springs
(
9.3
)
.
Thus
point
B
of
the
drive
lever
is
in
its
extreme
left
position
.
At
this
point
the
drive
lever
engages
with
the
cup
(
3.3
)
and
the
nut
(
3.4
)
of
the
vacuum
interrupter
.
This
holds
the
contacts
apart
(
in
the
OFF
position
)
against
the
atmospheric
pressure
.
When
the
magnet
coil
(
8.1
)
is
energized
,
the
armature
(
3.6
)
and
with
it
the
drive
lever
(
3.1
)
are
attracted
towards
the
magnet
core
(
8.2
)
against
the
reaction
of
the
two
compression
springs
(
9.3
)
.
Point
B
of
the
drive
lever
therefore
moves
to
the
far
right
position
.
The
nut
(
3.4
)
of
the
vacuum
interrupter
(
4.1
)
is
thus
released
so
that
the
atmospheric
pressure
can
press
the
moving
contact
against
the
fixed
contact
.
The
drive
mechanism
is
constructed
so
that
the
nut
(
3.4
)
never
comes
into
contact
with
the
drive
lever
(
3.1
)
when
in
the
ON
position
.
This
ensures
that
the
ON
switching
position
is
always
reached
,
definitely
and
completely
.
Blown
Fuse
Trip
Mechanism
Contactors
can
be
supplied
with
an
anti
-
single
phase
trip
mechanism
which
offers
protection
from
single
phasing
due
to
a
blown
power
fuse
.
Fused
contactors
equipped
with
the
blown
fuse
trip
mechanism
are
pre
-
adjusted
at
the
factory
so
that
the
opening
of
one
or
more
power
fuses
results
in
de
-
energizing
the
contactor
,
thus
interrupting
current
to
the
load
.
When
a
power
fuse
blows
,
a
plunger
extends
from
the
load
end
of
the
fuse
which
rotates
the
spring
-
loaded
trip
bar
and
releases
a
pre
-
compressed
micro
-
switch
on
the
side
of
the
contactor
.
A
contact
on
the
micro
-
switch
opens
at
this
time
and
de
-
energizes
the
contactor
magnet
coil
.
Figure
1
.
Operating
Components
of
Vacuum
Contactor
Courtesy of NationalSwitchgear.com