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PowlVac® CDR 27kV & 38kV Vacuum Circuit Breaker
IB-65020A
Installation
1) High Voltage Insulation Integrity
High voltages across the open gaps of the
vacuum interrupter can produce x-radiation.
When conducting high voltage test,
personnel should stand at least one meter
(3’) away from the circuit breaker with the
covers in place. Test voltages should not
exceed 60kVAC (85kVDC) for the 38kV rated
circuit breaker and should not exceed 45kVAC
(64kVDC) for the 27kV rated circuit breaker.
If the DC high potential testing (HIPOT) is
required, the DC high potential test machine
must not produce instantaneous peak
voltages exceeding 85kV for the 38kV rated
circuit breaker or 64kV for the 27kV rated
circuit breaker.
CAUTION
CAUTION
!
The primary circuit insulation on the circuit
breaker may be checked phase-to-phase
and phase-to-ground using a 2500V
insulation resistance tester. Since definite
limits cannot be given for satisfactory
insulation values when testing with an
insulation resistance tester, a record should
be kept of the insulation resistance tester
readings as well as the temperature and
humidity readings. This record should
be used to detect any weakening of the
insulation system from one check period to
the next.
To check insulation integrity, the AC high
potential test described below is strongly
recommended. Using DC testing is not
the preferred method, however, values are
provided due to the availability of DC test
sets.
CAUTION
CAUTION
!
If DC high potential testing is performed,
the DC high potential test machine must
not produce instantaneous peak voltages
exceeding 85kV.
The circuit breaker insulation should be
tested with the circuit breaker vacuum
interrupter contacts in the CLOSED
position.
Test each pole of the circuit breaker
separately, with the other 2 poles and
the frame grounded. Perform the field
dielectric test described in ANSI Standard
C37.20.2, at the voltage level appropriate
for the equipment
(Table A Field Dielectric
Test Values)
.
Table A Field Dielectric Test Values
Rated Maximum Voltage
(kV rms)
Power Frequency Withstand
(kV rms)
27.5
45
38
60
This test will have checked all of the
primary phase-to-ground and
phase-to-phase insulation.
