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52
Maintenance
PowlVac
®
STD Vacuum Circuit Breaker
IB-60201
3) Primary Resistance Check
This check is not required for routine
maintenance but it is recommended after
any major maintenance that requires
disassembly of any part of the primary
current path.
To check the resistance, pass a minimum of
100A DC through the circuit breaker pole,
with the circuit breaker closed. Measure
the voltage drop across the primary
contacts and calculate the resistance. The
resistance should not exceed the values
provided in this instruction bulletin for
the specific type and rating of the circuit
breaker being measured.
When making this test, be sure that the
test current passes through both main
horizontal primary disconnecting devices
of each pair, or the resistance measurement
will be affected. This may be done by
connecting the current source leads to two
blocks of full round edge copper 1” thick
by 3” or 4” wide by 4” long, and pressing
these blocks into the upper and lower
primary disconnecting devices of the circuit
breaker compartment. The voltage drop
measurement may be made between these
two blocks.
The micro-ohm values of resistance must
not exceed the following limits:
Table D Primary Resistance
Breaker
Type
Rated
(kV)
Rated
Continuous
Current A
Resistance
Micro-ohms
05PV36STD
4.76
1200
60
05PV36STD
4.76
2000
50
05PV50STD
4.76
1200
60
05PV50STD
4.76
2000
45
05PV50STD
4.76
3000
40
15PV25STD
15
1200
70
15PV25STD
15
2000
50
15PV36STD
15
1200
60
15PV36STD
15
2000
50
15PV50STD
15
1200
60
15PV50STD
15
2000
45
15PV50STD
15
3000
40
