Study on the Wetting Process and Its Influencing Factors of Pollution Deposited on Different Insulators Based on Leakage Current

Pollution-induced flashover has a serious threat on the safe and reliable operation of power systems. It is known that the pollution flashover voltage is directly related to the wetting degree of the pollution layer. But the wetting performance characteristics and control method of pollution layer on insulators have not been properly specified in the existing pollution test standards. In this paper, the wetting processes of the pollution layer on different types of insulators have been studied in an artificial fog chamber. In our test studies, the leakage current on the surface of polluted insulators under a different test environment is measured and then the curves of leakage current varying with time are plotted. Furthermore, the main influencing factors of the wetting process of the pollution layer have been analyzed in this paper. Test results show that the wetting process of the pollution layer can be characterized well through the change of leakage current, and when the leakage current reaches the maximum value, the pollution layer is saturated with fog. Specifically, during the wetting process, the leakage current gradually increases until the maximum value and then decreases; the time for the pollution layer to become saturated is dependent on the salt-deposited density (SDD), the steam fog input rate, the temperature in the artificial fog chamber, and the type of insulators. It is found that with the increase of SDD and the decrease of the steam fog input rate and the temperature in the climate chamber, the necessary wetting time will increase, and the more complex the insulator structure is, the longer the wetting time will be.

I. Introduction

Under FOG, dew, drizzle and other adverse weather conditions, polluted insulators may flashover under a lower applied voltage. So far though, the flashover accident caused by pollution is second to the most harmful one caused by lightning–the loss caused by pollution flashover accidents is ten times that caused by lightning [1], [2]. So great attention has been paid to the research of pollution flashover performance and its mechanism, and a lot of research work has been carried out [1]–[28].