Insulation optimization by electrode contour modification based on breakdown area/volume effects

This paper shows how to determine the electrode contour with the best insul ation performance on the basis of an area effect and a volume effect in the breakdown field strength. Previous electric field optimization techniques have provided us only with an optimum electric field distribution. For the design of power apparatus insulation, we have to consider the dielectric br eakdown characteristics rather than the electric field distribution. As a f irst step, we developed a new optimization technique which enables us to ob tain an optimum electrode contour with the highest breakdown strength while taking into account the area and volume effects of breakdown strength of i nsulating media. From the results, we have confirmed that the proposed opti mization method improved the breakdown voltage more than did the electric f ield optimization. This leads to an effective insulation design of electric power apparatus.