The Evaluation of Ceramic Insulator Performance around Thermal Power Plant in Indonesia

An evaluation was conducted upon the performance of installed ceramic support insulator in thermal power plant area which was allegedly causing several trip events of the adjacent 500 kV transmission lines. Several data were analyzed to evaluate the performance of the support insulator, such as technical design of the insulator, corona imaging result, thermo vision imaging result and pollution deposit analysis using scanning electron microscope (SEM). According to the design evaluation, the support insulator fulfilled the minimum creepage distance requirement for heavily polluted installation area or area with site severity (SPS) class “e”. Corona imaging results showed high corona discharge activity on top and middle segments of the support insulator, while thermo vision imaging results showed partial heating on the support insulator surface which indicated the presence of high leakage current due to pollution. SEM analysis result for pollution deposit on the surface of the insulator showed various chemical compounds including Chlorine which is commonly used as water treatment agent in thermal power plant. Chlorine exposure reduce the breakdown voltage of air especially during high humidity condition, thus increase the possibility of flashover which disturbed adjacent transmission line as phase to ground fault. Although the support insulator was design for heavy polluted area, proper cleaning must be done regularly to maintain the performance of the insulator.