MODELING OF THE SALT DISSOLVING PROCESS OF WET NATURAL POLLUTION ON SILICONE RUBBER INSULATORS

Summary

Silicone rubber (SIR) composite insulators have been widely used in the field of HVAC and HVDC voltage insulation for its excellent pollution flashover performance. The hydrophobicity and hydrophobicity transfer properties make water cannot form continuous water film on the polluted surface and therefore increase the flashover voltage. In recent years, it's discovered that when the contaminated composite insulators get wet, salt in the pollution layer cannot be dissolved out completely. This means that the flashover voltage depends not only on the separated droplets, but also on the reduced dissolved salts amount. In this paper, the process of salt dissolving was studied to find out how much salts could be dissolved versus the wetting time. An experiment simulating water dripping process was designed for the study of water penetration process. Furthermore, an artificial water droplet falling test was designed to simulate the salt dissolving process using a site SIR insulator as sample. The amount of salt dissolving out from pollution layer was recorded with time. The results show that the salt leaching process is a saturation process with salt dissolving rate which decreases with time. Based on this phenomenon, the water penetration process could be a diffusion process and a model based on Lucas-Washburn's Law is proposed. The studies also revealed wetting mechanism and salt diffusion mechanism of salt dissolving process and pointed out the process follows Fick's law.

Additional informations

Authors

Wiesbrock Frank, Tamus Zoltán Ádám, Esterl Florian Walter