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 degrees 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.>