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26
Installation
PowlVac 38™ ARM 3000A Series 4
Vacuum Circuit Breaker
01.4IB.65131
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Before shipment from the factory, all circuit
breaker functions are thoroughly checked. The
user must verify functions after receipt. Powell
recommends that the tests be performed in the
sequence listed below:
1) High Voltage Insulation Integrity
High voltages across the open gaps of the
vacuum interrupter can produce radiation.
Personnel should stand at least one meter
away from the circuit breaker with the covers
in place when conducting high voltage tests.
Test voltages should not exceed 60kVAC
(85kVDC) for the 38kV rated circuit breaker.
!
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. DC testing is not the
preferred method, however, values are
provided due to the availability of DC test
sets.
If DC high potential testing is performed, the DC
high potential test machine must NOT produce
instantaneous peak voltages exceeding 85kV.
!
CAUTION
The circuit breaker insulation should be
tested with the circuit breaker vacuum
interrupter contacts in the closed position.
The racking mechanism should be operated
to place the racking crank arms in the
“connected” position (rotated to the front
of the breaker, away from the primary
disconnecting devices) prior to performing
the dielectric testing. It is necessary that a
secondary disconnect override device be
used to permit rotating the racking shaft.
See
Ch 4 Installation, D. Placing the Circuit
Breaker Into Service, 4) Mechanical Operation
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
Rated Maximum Voltage
(kV rms)
Power Frequency
Withstand (kV rms)
38
60
This test will have checked all of the
primary phase-to-ground and
phase-to-phase insulation.
