AC pollution flashover performance and flashover process of glass insulators at high altitude site

The ac pollution flashover performance and flashover process of LXHY₃-I6O insulators was investigated at a high altitude site (altitude of 1400m) in this paper. The solid layer method was used, and even-rising voltage method was adopted. According to the test results, the average pollution flashover voltage (U_av) decreased with the increase of pollution, and there was no obvious relationship between the exponent characterising the influence of pollution and the length of the insulator strings. The relationship between U_av and the length of the insulator strings was nearly linear. Subsequently, the effect of the pollution and the length of insulator strings on the critical flashover arc trajectory were analysed. It concluded that the critical flashover distance (l_c) decreased with the increase of pollution, and it was shorter than the leakage distance (L₀), whereas there was no significant relationship between l_c/L₀ and the length of insulator strings. The arc appearance at the high altitude site was very irregular with obvious bending and rocking; the local arcs deviated from the surface of the polluted insulators even more seriously and the diameter was thicker than those obtained in the normal environment. Moreover, the brightness and diameter of local arcs was related to pollution.