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A DVAC® 3 8 K V I N STA LL ATI ON , OPE R ATI ON A N D M A I NTE N A NCE M A N UA L
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Maintenance
Primary withstand test
To perform the primary circuit withstand test
and verify the integrity of the primary insulation,
perform the following low frequency withstand
voltage test:
1. Close the breaker (no control power supplied
to breaker).
a. Connect the high potential lead to one pole.
b. Ground the remaining poles (control circuits)
and breaker frame.
2. Start machine with output potential
at 0 (zero) V AC.
3. Increase the potential to the required voltage
(see table for test voltage).
4. Hold for one minute.
5. Decrease potential to 0 (zero) V AC and turn
off machine.
6. Repeat for the remaining poles.
A successful withstand indicates satisfactory
insulation strength of the primary circuit.
To verify the integrity of the vacuum interrupters,
perform the following low frequency withstand
voltage test:
1. Open the breaker (no control power supplied
to breaker).
a. Connect the high potential lead to one terminal.
b. Ground the remaining five primary terminals
and breaker frame.
2. Start machine with output potential
at 0 (zero) V AC.
3. Increase the potential to the required voltage
(see table for test voltage).
4. Hold for one minute.
5. Decrease potential to 0 (zero) and turn
off machine.
6. Repeat for the remaining five terminals.
• A successful withstand indicates satisfactory
vacuum integrity.
• If flashover occurs, contact ABB Customer Service
(see contact information on the back cover of this
manual). Testing should be performed with an AC
source only. DC testing is not considered a valid
test for vacuum integrity. If DC is the only
available option, the peak DC voltage should not
exceed the corresponding AC RMS test voltage.
Additionally, a failure during DC testing should
only be considered preliminary. Additional AC
testing should be completed to determine if
replacement of the pole is warranted. Testing
with meggers (megohmmeters) or other similar
devices is not considered valid under any
circumstances.
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Primary low frequency withstand test voltages
Rated max voltage
Dielectric test value,
1 minute dry AC RMS
38 kV
80 kV
High voltage applied across an open gap in a
vacuum can produce x-radiation. When the breaker
is fully open, the contact spacing is such that when
tested with the voltages specified, x-radiation at
one meter is below the level of concern. A danger
could exist at voltages above the dielectric test
voltage or with reduced contact spacing caused by
a major internal mechanical failure of the breaker.
