System for on-line monitoring of pollution levels on solid insulators

This paper describes an online monitoring system which detects both partial discharges and the underlying power frequency leakage current on an insulator surface. This could allow degradation of the insulator performance to be monitored remotely. The sensing element would be a metal band fitted around the insulator close to the earthed terminal. High and low frequency components of current are separated and recorded in order that trends can be observed. A pollution model was devised which replicated the deposition of surface contamination on insulators in a practical laboratory experiment. The effectiveness of the experimental technique for detecting pollution build up was studied using this arrangement.