Partial Discharge FAQ

When will my high voltage (HV) asset fail? How do you best grade the severity of partial discharge (PD) when you find it?

When it comes to PD, time to failure is very difficult to predict but knowledge and engineering judgement are key when answering this question. The more we know about the discharging asset, history of failure, common failure modes, discharge type, its amplitude and physical location within/on the HV insulation of the asset, the better decisions we can make. Visual inspection and condition monitoring over time also provide an indication on asset life.

Again, engineering judgement always plays a part in measuring the severity of PD.

Key factors to consider:

➤ Type of Discharge – Internal, Surface, Corona, Contact

➤ Type of Insulation Discharging – Polymeric, Porcelain, Paper, XLPE, Cast Resin

➤ Discharge Site Position – High stress area, Close to earth, Close to another phase

➤ Discharge Amplitude – How do we grade its amplitude? Is a low amplitude a high risk of failure?

➤ Discharge Duration – How long has this been occurring for?

➤ Pulses per Cycle – Are they intermittent or continuous?

➤ Human Intervention – Have people been involved recently where changes are made to the asset?

Have more questions on anything PD?

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