37
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.
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.
High-potential tests
The next series of tests (vacuum-integrity
test and insulation tests) 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.
Vacuum integrity test procedure
1. Observe safety precautions listed in the
danger and warning advisories.
Construct the proper barrier and
warning light system.
2. Ground the frame of the circuit breaker,
and ground each pole not under test.
3. Apply test voltage (refer to Table 5:
High-potential test voltages on page 38)
across each pole for one minute (circuit
breaker open).
4. If the pole sustains the test voltage for
that period, its vacuum integrity has
been verified.
