Influence of shed forms on the leakage currents of barrel insulators

An attempt was made to study, in a natural environment, the influence of the insulator shed form on the pollution of the insulator and on its leakage current. Porcelain barrel insulators with eight different shed forms were energized by HVDC voltage and were exposed to natural pollution during a period of about four years in a site near a motorway. The insulators were energized with 100 kV DC voltage (DC power supply data: 100 kV, 400 mA) and their basic leakage current and the meteorological data were registered continuously by means of a data acquisition system. The SDD values of the polluted insulators were measured at intervals, especially after high leak current activities due to severe meteorological and pollution conditions