Tree initiation from artificial void with semiconductive electrode in PMMA

In this paper, it is shown that a semiconducting layer has an effect on the void discharge deterioration. Polymethylmethacrylate (PMMA) block 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 (PDPMS). At the same time, the void condition and the tree growth were observed by CCD camera. These measurements were carried out by SEs of several resistivities. 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 growth. The highest tree initiation voltage and the lowest tree extension speed were shown at a resistivity of 2 kΩ·cm