Condition monitoring of overhead line insulator by measuring surface leakage current

Transmission and distribution power network commonly use porcelain insulator for the isolation i.e. insulation between line conductors and supporting structure. Most of the insulators are mounting in open-air applications. So, gradually contamination is deposited in the surface of the insulator and reduced the voltage withstand capability of the insulator. This voltage withstands capability of the insulator measured in terms of surface flashover. This hampers the reliable operation of the power network. Hence condition monitoring of insulator is needed in order to maintain smooth and uninterrupted power supply. Surface leakage current of the insulator provides the meaningful information about the surface contamination as well as flashover voltage level of the polluted insulators. Considering the above mentioned fact, an experimental setup has been made in the laboratory for recording the leakage current of porcelain insulators. Using this setup, surface leakage current of an 11 kV Disc insulator has been measured in contaminated condition.