With the increase in power transmission in tropical countries, the study of the
effect of high humidities on the flashover characteristics of line and station insulation
assumes great importance. In this paper, the study of the variation of breakdown
voltages of gaps and different types of insulators with varying humidity at two constant
temperatures of 20 °C and 27° C, is reported. The range of humidity variation
obtained in a controlled atmosphere rootn was between 9 and 25 gln2 3, corresponding
to a relative humidity range of 60 to 90 per cent. The results point out to the
inaccuracies of the humidity correction factors as presently specified in the standards.
The study points out that no uniform correction factor could be applied to the flashover
voltages of insulators. The characteristics show three regions the first similar to
those of a rod gap, the second, a rapid rising region, and the third, a falling region.
Thorough investigations are proposed for future work.