A series of tests has conducted in an artificial climatic chamber to investigate the effect of altitude on dry and wet flashover voltage of insulators and air gaps. The results of tests show that the influence of attitude on dry flashover voltage is dependent on the test-object length

wavesharp

and the inluence of altitude on wet flashover voltage-the configurations of the test-objects

resistivity of water

etc.For each increase in the altitude of 100m

the average value of decrease of flashover voltage Δμ% for positive lightning impulse test is 1.06% and for the negative lightning impulse test-0.87%. The Δμ% for the dry and wet alternating voltage test are of 1.28% and 0.68%

respectively.