Partial discharge signals from TR-XLPE insulated cable

This paper reports on signal measurements from an unaged TR-XLPE-insulated cable at constant voltage stress, prior to the onset of partial discharge, as conventionally measured in time domain technique. Although physical events prior to partial discharge have been studied in the past, very few reports exist on signal measurements under pre-partial discharge conditions. Signal intensity vs. (a) time at constant voltage, and (b) electrical tree length have been measured; signal intensity increases logarithmically with time, both prior to and after an electrical tree is observed. Tree retardant components in the insulation do not prevent such signals from appearing. Relevant reports have been summarized and relevance to aging phenomena are discussed.