Partial discharge characteristic of electrical trees in polymeric cable insulation

Abstract

The growth mechanism of electrical tree in high voltage and extra high voltage dielectric system is needed for early identification, in order to resist the complete insulation failure. In power system equipment, electrical tree formation prevention is very much crucial for reliable and long term operation of cable section. There are so many varieties of electrical tree structure can formed from a weak region or a imperfection site in cable insulation viz branch-type trees, bush-type trees and bush-branch type trees depending on the voltage applied. Electrical treeing was developed in a needle-plane geometry using 5µm tip radius hyperbolic needle shape and a 2 mm gap from the tip of the needle to plane electrode in polymeric samples. This project was conducted by simulations based work in order to understand the characteristics of electrical trees in solid dielectric materials. In this work, electrical tree formation mechanism in solid dielectric material was modeled using MATLAB environment and done experimental work in high voltage laboratory with the application of 100 kV AC source with 50 Hz supply voltage. After the experiment the sample was viewed under FESEM for observation of electrical tree growth. It was found that the FESEM was particularly useful for searching for electrical damage in the polymeric insulation material where treeing phenomena takes place.