Mandava M. Rao and Mritunjay Kumar
Gas-insulated surge arrester, gas-insulated substation, leakagecurrent, resistive leakage current, protection
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. In view of above, IEC 60099-5 covers the various diagnostic methods and indicators for revealing the possible deterioration or failure of the insulating properties of surge arresters. According to the standards, most common and reliable diagnostic method is measurement of the arrester’s total leakage current and isolating its resistive component. This component is an indicator of the arrester’s condition, as deterioration or damage of arrester blocks lead to an increase of the resistive leakage current. In the present study, leakage current of a 145 kV GIS surge arrester prototype is measured and resistive component has been extracted in laboratory condition using two different techniques. Based on the techniques presented in this paper, a software module is developed and successfully tested for measurement of resistive leakage current. The importance of measurement and analysis of the results to assess GIS arrester condition is also discussed.
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