Modification of XLPE exposed to partial discharges at elevated temperature

Extensions are presented of research on partial-discharge-induced surface modifications of XLPE (crosslinked polyethylene) wherein the XLPE sample surface during corona exposure is maintained at an elevated temperature ranging up to 160°C. As for the ambient temperature case, circular degradation patterns are found, but their appearance and composition depend strongly on temperature. Furthermore, oxidation within a shallow (several micrometers) surface layer is found to increase sharply with rising temperature, an effect attributed to inward diffusion of corona-produced oxidizing species, particularly ozone and nitrogen oxides