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What is Partial Discharge (PD) and how do we test for it?

POSTED: 06 Jul 2021

What is Partial Discharge (PD) and how do we test for it?

What is PD?

Partial Discharge (PD) is an electrical discharge occurring within insulation that partially bridges conductors, as defined by IEC60270.

This phenomenon is caused by discontinuities or imperfections in the insulation system, often in voids or at insulation interfaces. PD serves as a crucial early warning sign of medium or high voltage insulation deterioration.

What if PD is untreated?

PD activity can indicate the presence of defects or weaknesses in the insulation, such as voids, impurities, cracks, or other forms of degradation. If left unchecked, PD can escalate to electrical treeing and surface tracking, leading to breakdown.

How do we test for PD

Testing for PD can be conducted both online and offline using various apparatus.






At Preformed Windings, we use Omicron waveform testing, and we also have a dedicated PD camera to test for PD Testing can be conducted.

Why do we test for PD?

Partnerships are at the heart of everything we do at Preformed Windings, so as a thought leader in the industry, we believe that our valued customers should receive the highest quality coils possible.

Continuous monitoring of PD activity can help predict impending insulation failures and allow for proactive maintenance or replacement of equipment before catastrophic failures occur.

Examining PD in great volume allows us to promise excellent performance to our partners.

Our services

When unsustainable PD levels are identified, Preformed Windings offers an alternative to costly asset replacement through high-quality, low PD coil manufacturing with short lead times. This minimizes downtime and reduces PD in existing machinery. Additionally, we excel in designing coils for enhanced efficiency and faster winding.

You can contact us here for any inquiries.

You can download our ‘What is Partial Discharge (PD)?’ official presentation here.




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