Field optimisation of high-voltage electrodes

Stresses on materials for HV components have become increasingly large owing to the reduction of their size and the worldwide increase in voltage levels. Since the electrical stress depends heavily on geometric factors, critical domains of an arrangement cannot be represented by such simple bodies as rings, spheres or cylinders. The paper describes an algorithm based on the CAD concept for optimising electrode contours according to given field distributions on their surfaces. This algorithm strictly separates field calculations and geometric corrections. The curvature change necessary to alter the contour is obtained by the simultaneous displacement of all contour points. Using this method, for example, a constant and minimum field strength, or a maximum initial voltage in air or SF6, is achieved. Tests were run on several HV components designed for practical use. The experimental results demonstrated the improvements predicted by the computer calculations.