Effect of absolute humidity on disruptive discharge voltage of standard sphere air gaps

The existing IEC standard prescribes humidity correction method of disruptive discharge voltage of standard sphere gaps, which is derived from experimental data under absolute humidity between 5 g/m³ and 12 g/m³. However, higher humidity is experienced in summer in Japan and also all over a year in tropical countries. In the present study, validity of the existing correction method is discussed for application up to 22 g/m³ based on a series of experiments for several years under natural humidity condition.