Effects of low pressure on DC pollution performance under different insulator profiles

A simplified physical model of insulator was designed to investigate the DC pollution performance at high altitude in this paper. Only two parameters, shed space and overhang, were considered in this model. The pollution flashover voltage of the model with different profiles was obtained through artificial pollution test carried out in Beijing (50m) and in Tibet (4300m). It was suggested that the degree of the pressure influence on the insulator was different under different profiles. The pressure dependence exponent changed from 0.2 to 0.4 with the change of shed overhang. The flashover processes were also observed by high speed camera. It is found that the development of the arc between two sheds showed different forms under different pressure. A statistics of the development of arc demonstrated that the different forms of arc development were the main reasons for the different pressure dependences.