Comparative analysis of the electric field distribution around high voltage fittings

This paper describes the use of a numerical technique for the evaluation of the electric fields around fittings for high voltage substations and plants. The aim is to identify “hot spots”, where the corona discharge occurrence is more probable. The analysis is based on threedimensional modelling by solving the electric field problem through the Boundary Element Method. Since the surface mesh required by the numerical technique can affect the validity of the results, particular attention is devoted to defining a suitable grid in order to obtain satisfactory accuracy in the predictions with a reasonable computational burden. The use of a modelling approach can reduce the onerous experimental tests, with the additional advantage of identifying possible modifications to limit or avoid the “hot spots”. Three types of high voltage fittings have been investigated by evaluating the electric field in the most critical points. On the basis of the results given by the numerical model, some modifications of the structure are proposed and verified, which allow the removal or a strong reduction of the “hot spots”.