Siemens vacuum circuit breaker 38-3AH3 38 kV - Manual (Page 50)

Maintenance
High-potential tests
The next series of tests (vacuum integrity
and insulation) involve use of high-voltage
test equipment. The circuit breaker under
test should be inside a suitable test barrier
equipped with warning lights.
Vacuum-integrity check (using dielectric
test)
A high-potential test is used to verify the
vacuum integrity of the circuit breaker. The
test is conducted on the circuit breaker
with its primary contacts in the OPEN
position.
High-potential test voltages
The voltages for high-potential tests are
shown in Table 3: High-potential test
voltages on page 51.
Note: Do not use dc high-potential testers
incorporating half-wave rectification.
These devices produce high-peak voltages.
High-peak voltages will produce X-ray
radiation. DC testers producing excessive
peak-voltages also show erroneous
readings of leakage current when testing
vacuum circuit breakers.
High-potential tests employ hazardous voltages.
Will cause death and serious injury.
Follow safe procedures, exclude unnecessary personnel and use
safety barriers. Keep away from the circuit breaker during
application of test voltages. Disconnect the split plug jumper
from between the circuit breaker and switchgear before
conducting high-potential tests.
Vacuum interrupters may emit X-ray radiation.
Can result in serious injury.
Keep personnel more than six feet away from a circuit breaker
under test.
X-rays can be produced when a high-voltage is placed across two
circuit elements in a vacuum.
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