Partial discharge arising from
localised defects in insulation
is the primary cause of system
failure in electrical distribution
equipment, accounting for up to
90% of electrical failures, according
to HVMS. Sporadic in nature, such
discharges may remain undetected
for some time, eventually developing
into unexpected system failures, with
potentially severe consequences.

Partial discharge refers to the
electrical discharge or spark which
can occur between two conducting
electrodes along a section of
insulation, typically in ageing cables
or defective joints and terminations.

The accumulation of energy from
partial discharge gradually weakens
the insulation, leading to a system
malfunction.

Martin Avis, operations manager,
says “People are put off by what they
imagine to be an expensive and
time-consuming process. For most
facilities, periodically carrying out a
partial discharge survey is a relatively
inexpensive exercise when compared
to off-line testing. The sophisticated
equipment we use means the test
procedure is non-intrusive and does
not require a power outage”.

HVMS recommends annual testing,
especially for critical plant.