Comparison of AC pollution flashover performance of insulators in chamber with high altitude spots

The electric performance of polluted insulator string may reduce under high altitude. The paper studies the AC pollution flashover performance of insulators at different height of altitude field and chamber climate separately. The test results show that: The deviation between test results with the artificial and field experiments is less than 8%, when the test carried out in climate chamber under low air pressure conditions, the characteristic exponent n describing the influence degree of air pressure on pollution flashover voltage which has influence on the pollution flashover voltage of insulators is mutative, and the value of n is related to the pollution, insulator type etc.. Under AC voltage, n is 0.50~0.60. The composite insulator is superior in external insulation selection in high altitude and heavy polluted areas. The results obtained by the test which carried out in climate chamber can guide the designing of the external insulation.