Fundamental investigations on the influence of temperature and water content on the electrical behavior of fluid impregnated insulating papers

This paper deals with fundamental investigations on the electric strength of liquid impregnated insulating papers namely aramid paper and cellulosic paper. These investigations point out that the breakdown voltage at 20°C of the two papers does not differ significantly. However their electric strength differs significantly at higher temperatures. Best results regarding the lifetime can be achieved by using ester liquid impregnated aramid paper. Therefore the combination of aramid and ester liquid proves to be more than an adequate substitute for mineral oil impregnated cellulosic paper. Finally the correlations between the water content of the impregnating liquid and the water content of the paper show that using ester liquid diminishes the water inside the insulating paper