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MAINTENANCE
CRITERIA:
1.
If a current flow above 5 milliamperes is observed
or if breakdown occurs, one or more of the
interrupters has insufficient vacuum and must be
replaced.
Exception:
If the current exceeds 5 milliamperes
the first time the voltage is brought up, reduce the
voltage to zero and increase it again. It may be
necessary to repeat this procedure a few times.
2.
If the contactor fails to meet criteria 1, then repeat
the test on each pole separately to identify the
damaged interrupter or interrupters.
3.
If the voltage can be held for 1 minute and the
current flow does not exceed 5 milliamperes, the
interrupter has a sufficient vacuum level.
After the test is complete, discharge any residual
static charge from the primary terminals of the
contactor.
If a vacuum checker or AC hi-pot tester is not
available, a DC hi potential test may be conducted. If
a DC test is conducted, the test voltage must be
increased to 14kV DC. The test duration for DC tests
and the criteria for acceptance remain the same as
for AC tests.
Do not use DC hi-pot testers
which employ unfiltered half-
wave rectifiers. The peak
voltages produced by these
testers may exceed the
recommended value of 14kV.
This can result in the
production of harmful X-rays
and may invalidate the test
results.
Figure 11 - Application of Test Voltage for
Vacuum Check
1 minute
10kV AC
(14kV DC)
Voltage
Zero
10 sec
10 sec
Time
WARNING
