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24
PowlVac® ASD 27kV & 38kV Vacuum Circuit Breaker
IB-65100
Installation
If the breaker is stored for any length of time,
it should be inspected periodically to see that
rusting has not started and to insure it is in
good mechanical condition. If the breaker
is stored under unfavorable atmospheric
conditions, it should be cleaned and dried out
before being placed into service.
D. P
LACING
THE
C
IRCUIT
B
REAKER
I
NTO
S
ERVICE
Before shipment from our 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
2. Vacuum
Integrity
3. Control Voltage Insulation Integrity
4. Mechanical Operation Check
5. Electrical Operation Check
6. Dimensional
Check
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.
After the high potential is removed, an
electrical charge may be retained by the
vacuum interrupters. Failure to discharge
this residual electrostatic charge could
result in an electrical shock. All six primary
disconnecting devices of the circuit breaker
and the metallic mid-band ring, if present,
should be grounded and remain grounded for
at least one minute to reduce this electrical
charge before coming into contact with the
primary circuit.
WARNING
WARNING
!
CAUTION
CAUTION
!
Remove all grounding conductors applied
for this test before placing the circuit breaker
back into service.
