Effect of Ambient Temperature on the Performance of Contaminated DC Insulators

Effect of ambient temperature simulating different weather conditions has been investigated on insulators of different shapes. It has been observed that for a given salinity of contaminating solution, the amount of salt contained in the contaminated-surface layer is strongly temperature dependent. This is attributed to the viscosity-temperature characteristics of the electrolytic solution. dc flashover voltage of contaminated insulators reduces by about 0.7 ~ 1.0% per degree centigrade rise in temperature. dc arc V-¿ characteristics are, however, temperature independent in the investigated range. The observed temperature dependence of dc withstand voltag of contaminated insulators is attributed exclusively to the change of resiudal resistance and a good agreement holds between the measured and the estimated values. The influence of polarity on contamination withstand characteristics is independent of temperature variations in the investigated range.