Effect of rainfall on contamination of porcelain and glass insulators: Experimental investigation

Rainfall causes decrease of contamination of insulators, which is closely related with the electrical performance of outdoor insulators of high voltage transmission lines, because it reduces the risk of pollution flashover. To study the washing effect of rainfall on contamination of porcelain and glass insulators, an artificial rainfall experiment platform has been designed, fabricated and tested. It can control rainfall´s intensity, flushing angle, duration, and homogeneous degree. Rainfall experiments of suspension insulator string have been performed. The results show that the residual ESDD and the residual NSDD on the surfaces of insulators decrease with the increase of the rainfall´s intensity(I), flushing angle(a), and duration(t). The effect of the rainfall´s flushing angle on washing contamination off insulators´ surface is more significant than the effect of the others, and rainfall´s intensity is the second. According to the experiment results, the negative exponential function relationships between residual ESDD, residual NSDD and I, t are gained while the base of the exponential function is Euler´s number e, so are the linear relationships between residual ESDD, residual NSDD and a.