Condition Monitoring of GIS Surge Arresters

Leakage current measurement plays an important role in determining the healthiness of high voltage insulation of a power apparatus. The accurate and real time measurement of leakage current enables the utilities to access the healthiness of the gas insulated surge arrester. This paper describes about the design, development, calibration and testing of a novel non-contact type passive leakage current sensor, which can be used for monitoring of gas insulated surge arresters. Metal enclosed gas insulated surge arrester is one of the important components of Gas Insulated Substation (GIS). These arresters are installed to protect various electrical equipment in the GIS against over voltages. While in service high-energy stresses may lead to degradation and damage of surge arresters. To establish capabilities of the developed sensor with optimized design parameters, laboratory measurements of leakage current on 420 kV and 145 kV GIS surge arrester prototypes have been carried out and reported in the paper. Third harmonic content of surge arrester leakage current has been estimated in-line with IEC requirement to assess the healthiness of the surge arrester. Finally, resistive component has been extracted from leakage current of a 145kV GIS surge arrester under laboratory conditions.