Abstract
Recently, high reliability and safty have been required for electric power system. Many kinds of insulating materials and insulating structures have been developed. Semiconducting layer is widely used to improve the relaxation of electric field of power cable. However, the characteristics of the layer are still not cleared. The purpose of this research is to investigate effects of semiconducting layer on void discharge deterioration. In this paper, PMMA with an artificial needle void at a tip of semiconductive electrode (SE) was used as a sample. The tree initiation voltage was measured. The discharge magnitude distribution was measured by the partial discharge pulse measurement system. At the same time, the void condition and the tree development was observed by CCD camera. These measurements were carried out by using SEs of several kind of resistivity.
As a result, by measuring the discharge magnitude distribution, it became clear that SE inhibited the void discharge. It was confirmed that the electrode inhibited tree development, by image processing of tree. The highest tree initiation voltage and the lowest tree extension speed were got at the resistivity of 2kΩ•cm. The effects of SE on the void discharge deterioration were caused by the conductive matter sputtered from the electrode.
