Effects of Absolute Humidity on Flashover Voltage of Insulators

Effect of humidity on flashover voltage of four kinds of porcelain and one polymer insulators was studied experimentally for several years under natural humidity condition in Japan. It was found that the existing IEC humidity correction seems to be proper for most insulators regardless of the kind of applied voltage but that change may be necessary for pin type insulator under positive lightning impulse voltage application and for unit suspension disk and station post insulators under AC voltage application. Key-Words: Insulators, Flashover voltage, Absolute humidity, Humidity correction