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Applications of VLF Technology
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Cables
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Cable
testing using VLF waveforms is an accepted
and standardised technique with much
literature available to support this. Many
standards refer to this method of testing
with published methods and parameters to
use.
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Cable
testing has historically been limited to
overvoltage/pressure testing where the cable
is subjected to a voltage in excess of its
rated voltage for a fixed period of time.
The cable must be able to withstand the
voltage application for the duration of the
test. Failure to pass the test would mean
that the cable cannot be reconnected into
service. Overvoltage testing can be DC, VLF
or 50Hz.
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For
a number of valid reasons (besides the price
of DC Hipots), DC testing has lost favour as
the preferred means of testing, especially
for extruded cables. DC testing is still
used for a sheath test.
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Cable
diagnostic testing is possible using VLF
test sets where an indication of the overall
health of the cable is now possible. Cables
can be easily and quickly tested and a
qualitative indication of their performance
can be obtained.
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