Identifying Partial Discharge & Reducing it with Specialist Coils

POSTED: 06 Jul 2021

Identifying Partial Discharge & Reducing it with Specialist Coils

Partial Discharge (PD) is defined by IEC60270 as “A localised electrical discharge that only partially bridges the insulation between conductors and which can or cannot occur adjacent to a conductor”.

This event occurs due to discontinuities or imperfections in the insulation system. These imperfections can occur in the voids or cavities in solid or liquid insulation or at the interface between insulation layers.

The reason we test for PD is that it is regarded as being one of the best ‘early warning’ indicator of deterioration of medium or high voltage insulation. If left untreated PD can develop into electrical trees and surface tracking, eventually leading to a breakdown.

To identify PD, testing can be done both online and offline using a number of testing apparatus including High Voltage Coupling Capacitors (HVCC), High-Frequency Current Transformers (HFCT) and Rogowski Coil Sensors (RC).






Our strategic partners, HVPD, recommend using their 4-Phase (OLPD) Online Partial Discharge Asset Management Solution. This solution combines a complete range of OLPD spot test and monitoring technology. The solution provides the framework for a systematic and cost-effective, condition-based asset management system for high voltage (HV) networks that identifies, locates, monitors and manages OLPD activity within the customer’s HV network through four phases.






OLPD allows for trends in activity to be observed over time. While PD is brought on by high-voltage stresses, it can be influenced by the operating environment including Load, Temperature, Humidity, etc. As PD activity is often present well in advance of insulation failure, it is possible to monitor and make strategic decisions regarding the refurbishment and renewal of the asset or its parts to offset PD faults.

Once HVPD has identified unsustainable levels of PD, Preformed Windings can help avoid the costly replacement of an older asset by assisting with condition-based maintenance by manufacturing high quality, low PD coils at short lead times. This reduces your downtime and allows for the significant reduction of PD in your existing machine. This is just the start though, as well as being the industry leaders in manufacturing low PD coils, we can also design coils for improved efficiency and faster winding times.

Our post on the best strategy for producing high-quality low PD coils will be available shortly.

If you would like to discuss your requirements with the team please don’t hesitate to call James Stevens on +44 (0)7825 092563. We are available 24/7!

Alternatively, you can contact us here.




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