Partial Discharge - Hidden Hazard

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. Prevention is easy with the modern non-intrusive testing methods now available.

[UKPRwire, Mon Aug 17 2009] 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.

Sporadic in nature, such discharges may remain undetected for some time, propagating and eventually developing into unexpected system failures, with potentially severe consequences.

Prevention is easy with the modern non-intrusive testing methods now available according to Power Engineering specialist HVMS, who recommend regular annual testing as part of a proactive maintenance regime, especially for critical plant applications.

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. Presenting in solid insulation, within gas bubbles in liquid insulation or around electrodes in gas, the accumulation of energy from partial discharge gradually weakens the insulation, leading eventually to a system malfunction. This may take the form of a breakdown to earth or an interruption between phases in multi-phase systems.

A lack of understanding about how the latest testing techniques work, coupled with increasing constraints on budgets mean that testing for partial discharge is often overlooked when it comes to planned maintenance and asset management.

Perceived cost and the risk of downtime can be a deterrent, explains Martin Avis, Operations Manager at HVMS.

“People are put off by what they imagine to be an expensive and time-consuming process. In point of fact, for most facilities, periodically carrying out a partial discharge survey is a relatively inexpensive exercise when compared to off-line testing.”

He adds: “Equally important, there is no disruption involved. The sophisticated equipment we use means the test procedure is non-intrusive and does not require a power outage”.

Another barrier in the past has been a lack of confidence in the test results. Stresses Martin Avis: “The advanced technology we employ is 100% accurate offering a truly predictive test that can provide early detection. In most instances we are able to pinpoint the site of the Partial Discharge, enabling the localised problem to be repaired quickly and thus avoid potential failures”.

The capacity to store data results allows active year on year comparison, making it easy to identify areas of increased risk due to ageing equipment and to budget ahead for essential repairs or replacements.

For more information on HVMS testing services call 0845 644 4867 or email enquiries@hvms.co.uk


Issued by Shere Marketing. For press information and high resolution images contact Charmaine Kimpton on 01483 209305 or email ckimpton@sheremktg.co.uk