Long term analysis of leakage current pulses registered by an optical sensor network

The loss of insulation capacity caused by pollution deposition on insulator strings can be inferred from the analysis of the electric arcs due to partial discharges on the insulators. The partial discharges also cause pulses superposed to the leakage current signal. An optical sensor system network was developed and installed in the northeast region of Brazil to monitor the degree of pollution deposited over insulator strings of high voltage transmission lines. The monitoring system comprises leakage, humidity and temperature sensors, a processing electronic module and a satellite communication link. They were installed on 230 and 500 kV towers. This paper presents a correlation study comparing the information obtained from the monitoring systems and the electric arc levels obtained by traditional visual inspections. Also the rain events influence the leakage current behavior and a rain pattern recognition system is used in order to better evaluate the leakage current behavior.