Siemens GMI Series - Page 31

Maintenance
&
Overhaul
Page
28
As
-
Found
Insulation
Tests
As
-
Found
tests
verify
the
integrity
of
the
breaker
insulation
system
.
Megger
or
Doble
tests
conducted
on
equipment
prior
to
installation
provide
a
basis
of
future
comparison
to
detect
changes
in
the
protection
afforded
by
the
insulation
system
.
A
permanent
record
of
periodic
As
-
Found
tests
enables
the
Maintenance
organization
to
determine
when
corrective
actions
are
required
by
watching
for
sudden
deterioration
in
insulation
resistance
,
or
increases
in
contact
resistance
.
A
CAUTION
Vacuum
interrupters
may
emit
X
-
ray
radiation
which
can
cause
personal
injury
.
X
-
rays
can
be
produced
when
a
high
voltage
is
placed
across
two
circuit
elements
in
a
vacuum
.
Keep
personnel
more
than
six
(
6
)
feet
away
from
a
circuit
breaker
under
test
.
Test
Equipment
In
addition
to
the
High
Potential
Test
Equipment
capable
of
test
voltages
as
listed
in
Table
3
,
the
following
equipment
is
also
required
:
•
Ac
Hi
-
Pot
tester
with
test
voltage
of
1125
volts
,
60
High
Potential
Test
Voltages
The
voltages
for
high
potential
tests
are
shown
in
Table
3
.
Table
3
.
Hi
Pot
Test
Voltages
Hz
.
•
Ductor
for
contact
resistance
tests
.
As
-
Found
Test
Procedure
1
.
Observe
safety
precautions
listed
in
the
danger
and
caution
advisories
for
the
Vacuum
Check
tests
.
2
.
Close
the
circuit
breaker
.
Ground
each
pole
not
under
test
.
Use
manual
charging
,
closing
and
tripping
proce
-
dures
3
.
Apply
the
proper
Ac
(
i
.
e
.
,
either
14
or
27
kV
)
or
Dc
(
i
.
e
.
,
either
20
or
38
kV
)
high
potential
test
voltage
between
a
primary
conductor
of
the
pole
and
ground
for
one
minute
.
4
.
If
no
disruptive
discharge
occurs
,
the
insulation
system
is
satisfactory
.
5
.
After
test
,
ground
both
ends
and
the
middle
of
each
vacuum
bottle
to
dissipate
any
static
charge
.
6
.
Disconnect
the
leads
to
the
spring
charging
motor
.
7
.
Connect
all
points
of
the
secondary
disconnect
with
a
shorting
wire
.
Connect
the
shorting
wire
to
the
high
potential
lead
of
the
high
voltage
tester
,
and
ground
the
breaker
housing
.
Starting
with
zero
volts
,
gradually
increase
the
test
voltage
to
1125
volts
,
RMS
,
60
Hz
.
Maintain
test
voltage
for
one
minute
.
8
.
If
no
disruptive
discharge
occurs
,
the
secondary
control
insulation
level
is
satisfactory
.
9
.
Disconnect
the
shorting
wire
and
re
-
attach
the
leads
to
the
spring
charging
motor
.
«
Equipment
kV
Rating
Max
Dc
Avg
Max
Ac
RMS
20
kV
38
kV
14
kV
27
kV
27
kV
4.76
kV
8.25
kV
15.0
kV
38
kV
A
CAUTION
Do
not
use
Dc
high
potent
al
testers
incor
-
porating
half
-
wave
rectification
These
devices
produce
high
peak
voltages
.
h
These
high
voltages
will
produce
X
-
ray
radiation
.
These
devices
also
show
er
-
roneous
readings
of
leakage
current
when
testing
vacuum
circuit
breakers
Vacuum
Integrity
Test
Procedure
1
.
Observe
safety
precautions
listed
in
the
danger
and
caution
advisories
.
Construct
the
proper
barrier
and
warning
light
system
.
2
.
Ground
each
pole
not
under
test
.
3
.
Apply
test
voltage
across
each
pole
for
one
minute
.
4
.
If
the
pole
sustains
the
test
voltage
for
that
period
,
its
vacuum
integrity
has
been
verified
.
4
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