Page 39 - Energize April 2021

TECHNICAL

Advances in partial discharge

monitoring

Information from Megger

Keeping the power on is vital to the success of any network operator, and that means ensuring that
high voltage assets operate at optimum efficiency. But partial discharge – a low energy electrical
discharge that can occur in any insulating medium – can gradually erode insulation resistance in
transformers, switchgear, generators, motors, cables, and other electrical equipment.

he cost of subsequent failures distribution network operators and private or industrial network operators. The suite of
is likely to be measured in products was expanded in 2019, with Megger’s acquisition of Power Diagnostix, a German
Tunplanned outages, missed specialist in PD testing.
performance targets and regulatory fines “We have a wide range of customers, from distribution network operators that might need
– or possibly in fires, explosions, and to monitor across an entire region, to customers in the high-tech manufacturing sector, where
serious injuries. For network operators, security of supply is vital,” says Tony Wills, applications engineer at Megger.
monitoring partial discharge (PD) activity In the UK, networks typically operate HV equipment which was originally installed in the
is therefore an essential element in safe 1970s and 1980s; PD testing activity is therefore becoming more critical as these assets age.
and secure operations. Meanwhile, continuous monitoring technologies, where sensors are clamped to equipment so
But monitoring assets for PD isn’t that signals are recorded and uploaded for analysis every few seconds, have been available
straightforward: it can be linked to faulty for roughly the past two decades. As a result, Wills notes, these systems are more prevalent
workmanship in the manufacturing stage, in countries with a more youthful energy infrastructure, such as in the Middle East and Africa.
poor site practices at installation, or However, this type of monitoring is becoming more common in the UK, as assets are replaced
failures at any point in what is likely to be or upgraded.
a long design life. In addition, PD at low
levels might not trigger a need for action, How PD testing is conducted
if the fault falls below levels set out in the Transformers, switchgear, motors, and
international standards document IEC cable installations are typically not easily
60270, often referred to as the ‘bible’ of accessible for inspection or repair. However,
partial discharge measurement. PD monitoring techniques provide a variety
Only by monitoring PD levels over of options to “see” what’s happening inside
an extended period and identifying and these valuable assets.
tracking changes in PD activity as soon as PD testing exploits the fact that PD
it occurs, can asset owners be confident activity emits both sound waves and high
that they have identified red flag issues, frequency electromagnetic signals: Megger’s
or indeed be reassured that their
equipment is operating at optimum
efficiency. With the operational integrity
of valuable assets at stake, owners
and operators need reliable, easy to
use testing equipment backed up by
after-care and expertise.
Power Diagnostix by Megger,
known for its range of hand-held PD
sensors for rapid diagnostic testing,
has recently expanded its suite of PD
measuring equipment to meet the testing
needs of equipment manufacturers,

energize | April 2021 | 37