Characteristics of streamer propagation along the insulation surface: Influence of air pressure and humidity

Most of the UHV transmission lines passed the high altitude and high humidity area. It was necessary to study the influence of air pressure and humidity on characteristics of flashover along the insulation surfaces. In the three-electrode arrangement, the characteristics of streamer propagation in air alone and along the silicone rubber surface were measured at Shenzhen, Kunming, and Yangbajing, respectively. The data of the streamer `stability' propagation field and velocity were measured at the different air pressure and humidity. Empirical equations were presented expressing the effects of the air pressure and humidity on the streamer `stability' propagation field and velocity. Furthermore, the variation of the streamer `stability' propagation field and velocity with air pressure and humidity was analysed. The test results showed that the streamer stability propagation field was in proportion to air pressure or humidity. Under the same electric field, the streamer propagation velocity was in inverse proportion to air pressure or humidity. Therefore, it was easier for streamer propagation in the lower air pressure or humidity. Furthermore, the effect of the humidity and air pressure on stability fields of streamer propagation along silicone rubber surface was larger than that in air alone.