Investigation of Pollution Severity and Dry Band Characteristics on 11kV Composite Insulator

Composite insulators have been extensively used in power sector because of its superior hydrophobicity property. The outstanding electrical and mechanical property makes the better dielectric material for producing such high voltage composite insulators. This paper investigates the flashover mechanism of 11kV composite insulators under various polluted and dry band conditions. The factors influencing the flashover voltage like leakage distance, location of dry band, geometric profile of insulator was also investigated. The pollution tests were carried out based on solid layer method and the average flashover voltage was obtained using even rising method based on IEC 60507. The NaCl : kaolin ratio was taken under 5:10,10:10,15:10 and 20:10 where the kaolin ratio was maintained constant. To verify the severity of the pollution obtained from the test results it is compared with IEEE standard. The outcome of this study provides a better knowledge regarding the flashover mechanism of composite insulator under polluted dry band conditions which can be used to improve the existing methodology and useful reference for design and operation of insulators under contaminated conditions.