Siemens 81000 90H35

Maintenance
Page
14
Since
loss
of
vacuum
is
accompanied
by
loss
of
dielectric
strength
,
bottles
may
be
tested
for
sufficient
vacuum
level
by
performing
a
high
potential
dielectric
test
across
the
contacts
with
the
contactor
in
the
open
position
.
Main
Contacts
Wear
Check
The
recommended
method
of
determining
main
contact
wear
is
to
keep
records
as
accurately
as
possible
of
the
number
of
daily
switching cycles
along
with
the
amount
of
current
being
interrupted
.
By using
this
data
and the
graph
of
electrical
life
,
Figure
13
,
it
can
be
determined
with
sufficient
accuracy
when
the
contacts
in
the
vacuum
bottles
have reached
the end
of
their
service
life
.
At
this
point
,
the
vacuum
bottles
should
be
replaced
by
following
the instructions under
"
Vacuum Bottle
Replacement
.
"
It
should
be noted that
probability
of
replacing
a vacuum
bottle due
to
contact
wear
is
very
low
,
due
to
the
exceptionally
long
mechanical
and electrical
switching
life of
the
Siemens
VS
-
6602
vacuum
bottle
.
AWARNING
Excessive
dielectric
test
voltages
can
cause
harmful
x
-
radiation
to
be
emitted
from
vacuum
bottles
.
Do
not
exceed
13
,
250
volts
RMS AC
or
19
kV
DC
when
performing
dielectric
tests
.
AWARNING
Accidental
contact
with dielectric
test
equipment
can cause
shock
,
burn
or
electrocution
.
Dielectric
testing
should
only
be
con
-
ducted
by
qualified
personnel
.
Refer
to
test
device
instructions
for
safety
instruc
-
tions
.
With
the
vacuum
contactor
withdrawn
from
the controller
and
in
the
open
position
,
apply
13.25
kV
RMS
AC
across
the
open
contacts
of
each
bottle
for
one
minute
.
No breakdown
should
occur
.
If
breakdown
occurs
on
any
vacuum
bottle
,
it
must
be
replaced
.
If
a
DC
hi
-
pot
tester
is used
,
a
test
voltage
of
19
kV
DC
should
be
applied
.
FIGURE
13
.
Electrical
Life
Curve
Vacuum
Loss
Check
It
is
highly
unlikely
that
a
vacuum
bottle
will
ever
suffer
loss
of
vacuum
.
The
vacuum
bottle
has been
designed
and tested
to
maintain
the
level
of
internal
pressure
necessary
to
proper
operation
for
at
least
20
years
of
shelf
life
.
Since
switching
under
load
tends
to
increase
the level
of
vacuum
,
due
to
a
phenomenon
known
as
“
gettering
”
,
the
life
of
bottles which
have
been
placed
in
operation
will
be extended
even
further
.
Courtesy of NationalSwitchgear.com