Protecting MV cable insulation from failure due to Partial discharge (PD)

By P Ebersold, Marmon Utility

Published in:

Electricity+Control, June 2014 (pages 4-5)

Email:  powercable@kerite.com

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Read the full article on Protecting MV cable insulation from failure due to partial discharge in PDF format.

 

Design engineers must ensure the reliability of solid-dielectric power cable against failures caused by Partial Discharge (PD). Engineers can guard against Partial discharge (PD) by using two very different methods, designing cable to be either discharge-free cable or discharge-resistant cable. The article discusses these methods and shows that the discharge-resistant cable standard leads to far greater overall system reliability.

 

Partial discharge (PD) or corona electrically ages cable – voids and contaminants are sites where this deterioration begins. Partial discharge (PD) happens when an electric field inside the void exceeds the breakdown threshold of the gas in the space. The electrical breakdown pulses occurring in microscopic voids and contaminants cause fracturing of the insulation, resulting in points of high stress.

 

Take note

  • Partial discharge (PD) activity destroys your cable.
  • Partial discharge (PD) is a similar mechanism to corona but occurs within voids in the insulation.
  • Partial discharge (PD) materials for use in cable have been developed.