Natural Pollution Test of Insulators Energized with DC High Voltage

Various types of insulators have been energized with ±250 kV dc voltage and exposed to natural conditions by the seaside continuously. Salt deposit density and flashover phenomenon of these insulators have been investigated extensively for about two years. According to the results obtained so far, the influence of dc voltage application on the salt deposit density was not so notable as expected, while the effect of insulator types on the voltage withstand strength was greater than anticipated.