Temperature distribution along an outdoor insulator subjected to different pollution levels

The appearance of dry bands on polluted insulator surfaces may cause the ignition of electrical arcs, which in turn give rise to tracking and erosion, or may elongate until they bridge the electrodes causing flashover. Efficient models able to predict the occurrence of such a severe problem are of paramount importance for the engineer involved in the design of power line insulation. The present paper concerns the evaluation of the temperature distribution along the surface of an outdoor insulator subjected to pollution of different severity in order to predict dry band formation. The proposed numerical procedure, based on the joint solution of Maxwell equations in their quasi-static formulation and thermal equations, has been applied to study the case of a suspension cap-and-pin glass insulator, covered with pollution layers of different conductivity and thickness. The dependence of the conductivity of the layer on the temperature has been taken into account properly. The influence of uniform and nonuniform pollution distribution on the temperature profile is discussed for an applied sinusoidal power frequency voltage