Light emission from polyethylene subjected to highly divergent fields

Abstract

It is well known that polymers such as polyethylene can deteriorate under high electrical stress. This deterioration is usually in the form of electrical trees when the polymer is dry or water or electro-chemical trees in a wet environment. The tree initiation, before the tree becomes visible, is not fully understood. There is evidence that light is emitted during the electrical tree initiation process at both cryogenic and room temperatures [1,2]. Light has also claimed to have been detected during the growth of water trees [3]. This light has been attributed to electroluminescence or partial discharges ocurring in small voids near the needle tip. Previous studies have not attempted to detect partial discharges while measuring the light. This paper describes initial results of tests to measure simultaneously the light and partial discharge characteristics from a needle/plane electrode system in polyethylene.