AC Fog Withstand Test on Contaminated Insulators by Steam Fog

This paper describes the results of an investigation into how steam fog parameters affect the withstand voltage of artificially contaminated insualtors by the fog withstand method. We established the correlation between the steam flow rate and liquid water content of the fog. The fog withstand voltage showed a lower value with little dispersion at about 3 to 10 g/m3 of the maximum liquid water content. The minimum fog withstand voltage agreed well with the minimum flashover voltage obtained under natural conditions. We suggest that, for the fog withstand test using steam fog, the ideal fog condition would be about 3 to 7 g/m3 of the maximum liquid water content of the fog.