GE PVDB-28kV Instructions Manual page 23

Distribution Breaker Section 8. Main
2. Primary Circuit -The breaker should be hi-potted
in the closed breaker mode. An AC hi-pot machine
capable of producing the test voltages shown below
may be used to hi-pot the breaker phase to phase
and phase to ground.
TEST VOLTAGE
60 HZ lR~
BREAKER VOLTAGE
R~.!!!!.g
45 kV
25.8 kV
If no breakdown occurs the interrupter is in acceptable
condition. After the high potential voltage is removed,
discharge any electrical charge that may be present
through the internal ground of the test machine or be a
grounded cable to one of the phase bus bars.
If a failure of a vacuum bottle should incur during the
integrity test, the test procedure should be reviewed and
the pole piece cleaned. GE failure rate for vacuum
bottles is 0.0007 per field unit.
Note the voltage level at failure on the first test, and
retest the phase pole piece. If the pole piece passes the
second test, the vacuum bottle is acceptable -STOP. If
the test fails again, but at a higher voltage level than was
observed inn the first test, clean the pole piece and
retest. If a failure of the integrity test occurs a third time,
consider the vacuum bottle to have lost vacuum and
replace the complete pole piece as described under
Replacement of Interrupter Assemblies, section 9-2.
Although a AC hi-potential test is strongly recom-
mended for checking the- vacuum integrity, a DC hi-
potential test can also be conducted on the vacuum
interrupters at 50 kVand held for 10 seconds with the
restrictions noted as follows:
The machine should be connected with its output
potential at zero and the voltage increased to the
test voltage and that voltage maintained for 00
seconds. The voltage should then be returned to
zero and the hi-pot machine removed from the
circuit. NOTE -Do not exceed the test voltage
indicated for the applicable breaker voltage rating.
If the test should experience a failure, STOP, turn
off the test set and discharge the breaker circuit.
I. Check the test setllp and leads for connection
errors.
2. Wipe down the breaker to remove any moisture,
dust and contamination.
3. Retest the breaker at the proper test voltage.
8-8 Vacuum Interrupter Integrity
Test
No attempt should be made to try to compare the
condition of one vacuum intemlpter with another nor
to correlate the condition of any interrupter to low
value$ of DC leakage current. There is no sig!!ifi£~nt
correlation.
The vaCUllm integrity test is performed using an AC hi-
potential tester. A vacuum integri~ test of the
inteml1;!ter is reQuired to insure that no loss of vacuum
has occurred. This test of the vacuum interrupter will
determine its internal dielectric condition and vacuum
integrity. With the breaker open individually check
each intemlpter by connecting the hi-pot machine 'hot'
lead to the primary bus bar and the grolmd lead to the
load side bus bar. If the machine has a center point
grolmd, the connections may be made either way. Apply
36kV (rms) 00 Hz at 500 vps and hold for 10 seconds.
Mter the high-potential voltage is removed, discharge
any electrical charge that may be retained.
An acceptable AC high-potential machine is available
from the Switchgear Operation, Burlington, Iowa,
Catalog Number 282A2610POOI. Other acceptable AC
high potential machines are:
Hipotronics Model 7BT OOA
Hipotronics Model OOHVT
James G. Beddle Catalog 222000
Phoenix Model600-10P
Acceptable DC high potential machines are:
Hipotronics Model 800PL
Hipotronics Model 880PL
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