Luminescence in polymeric insulation and its implication on insulation aging

This paper describes the characteristics of three types of light emission that can occur from polymeric insulation subjected to uniform and divergent electric fields and/or high temperature. 1. Electroluminescence (EL), which is the light emitted at points of electric stress enhancement in the polymer occurs much before partial discharges (PD). EL can occur at cryogenic temperatures and at and above room temperatures. 2. Light emission which occurs from the surface of the polymeric insulation due to electron bombardment at high electric stress in high vacuum. 3. Thermoluminescence (TL), i.e. emission of light at elevated temperatures (>50°C) caused by the presence of crosslinking byproducts in cable insulation. No electric stress is required for TL emission. The implications of light emission on polymer degradation and additives that have been successfully used to retard degradation are described