Comparison of AC pollution flashover performances for composite insulators with different configuration under low atmospheric pressure

This in order to find out the optimal configuration of composite insulator under high altitude and pollution region, laboratory comparison studies were carried out on the pollution flashover performance of four configurations composite insulators (the number is seven in all) in the big multi-function artificial climate chamber. The influences of configuration parameters, salt deposit density (SDD) and atmospheric pressure on the flashover gradient EL of the test samples were analyzed. The big-small umbrella configuration composite insulator with the 3.55 CF coefficients (ratio of creepage and dry-arc distance) had the biggest E_L and optimal pollution performance under the 2500 m altitude. When the altitude reached 4000 m, the same umbrella configuration composite insulator with the 3.27 CF coefficients had the best pollution performance. There is a general tendency for higher altitude the smaller value of the optimal CF.