EFFECT OF HUMIDITY ON BREAKDOWN VOLTAGES OF GAPS AND INSULATORS

Abstract

With the increase in power transmission in tropical countries, the study of the effect of high humidities on the flash over 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 room was between 9 and 25 g/m^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 flash over 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.