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58
Maintenance
01.4IB.77020
PowlVac-ND
®
and PowlVac-NDA
™
Series 4
Vacuum Circuit Breakers
2) Timing
Perform
CLOSE
and
OPEN
timing tests at
the nominal control voltage. The voltage is
printed on the circuit breaker nameplate.
To measure
CLOSE
timing, operate the test
source to the
CLOSE
position. When the
circuit breaker closes, record the closing
time. The closing time from energizing the
closing coil to vacuum interrupter contact
touch should not exceed the values in
.
Table C Timing
Cycles
Closing Time
(ms)
Tripping Time
(ms)
3
<80
<35
5
<80
<55
To measure
OPEN
timing, operate the test
source to the
OPEN
position. When the
circuit breaker opens, record the closing
time. Operate the test source to the
OPEN
position to open the circuit breaker and
record the opening time. The opening
time from energizing the shunt trip coil to
vacuum interrupter contact part should not
exceed the values listed in
3) Primary Resistance Check
The primary resistance 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 primary 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 the
test current passes through both main
horizontal primary disconnecting devices
of each pair or resistance measurement
will be affected. This may be done by
connecting the current source leads to
two blocks of full round edge copper ¾”
thick by 3 or 4 inches wide by 4 inches long
and pressing these blocks into the upper
and lower primary disconnecting devices
of the circuit breaker. The blocks should
be silver or tin-plated to simulate the
primary disconnecting devices in 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 limits in
.
Table D Primary Resistance
Breaker
Type
Rated
(kV)
Continuous
Current
(Amperes)
Resistance
(Micro-ohms)
05PV36SNDX-4
5
1200
100
05PV36SNDX-4
5
2000
80
05PV50SNDX-4
5
1200
100
05PV50SNDX-4
5
2000
80
05PV36SNDM-4
5
1200
100
05PV36SNDM-4
5
2000
80
05PV50SNDM-4
5
1200
100
05PV50SNDM-4
5
2000
80
05PV36NDAX-4
5
1200
100
05PV36NDAX-4
5
2000
80
05PV50NDAX-4
5
1200
100
05PV50NDAX-4
5
2000
80
05PV36NDAM-4
5
1200
100
05PV36NDAM-4
5
2000
80
05PV50NDAM-4
5
1200
100
05PV50NDAM-4
5
2000
80
