Partial Discharge Testing

It is essential to detect and monitor Partial Discharges as the phenomenon is an indicator of pending insulation breakdowns. Prevention is far better than operational disruption and expensive repairs.

Partial Discharge can occur within the insulation system of any electrical distribution asset. The consequences can be severe, leading to disruptive failures that are unacceptable in critical electrical distribution equipment.

Partial Discharge Testing is a cost effective and non-intrusive technique for ensuring supply reliability and long term operational sustainability.

Analysis can be performed under normal operating conditions with no interruption to power supply.

What is Partial Discharge?

In high voltage electrical engineering, a Partial Discharge is a localised dielectric breakdown of a small portion of a solid or liquid electrical insulation system under high voltage stress.

Electric corona together with the nitrogen and moisture in the air produces ozone and nitric acid - this in turn will break down the main insulation, causing disruptive failure of the termination.

Partial Discharge activity can occur under normal working conditions in high voltage equipment where the insulation condition has deteriorated with age, and/or has been aged prematurely by thermal over-stressing. Partial Discharge can also be observed on equipment with an improper installation, design and/or workmanship.

IEE statistics indicate that electrical insulation deterioration causes up to 90% of electrical failures of certain high voltage equipment.

The benefits of partial discharge testing

• It is truly a predictive test, indicating insulation degradation in advance of the failure
• It is a non-intrusive test, requiring no interruption of service and is performed under normal operating voltage and load
• It is a non-destructive test; it does not test to failure or adversely affect the equipment under test
• It need not use any over-voltages, thereby not exposing the tested equipment to higher voltage stresses than those encountered under normal operating conditions
• Trending can be accomplished by storing results to allow comparison with future tests
• In many instances the site of the partial discharge occurrence can be located within the test objective, thus enabling the localised problem to be repaired
• The cost to perform a PD survey is relatively inexpensive compared with the off-line testing, allowing annual surveys to be performed economically at most facilities

Contact us to discuss your requirements and for a costed Partial Discharge Test proposal.

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