On optimization of the insulation of high-voltage coaxial bushing

Abstract

This paper considers ways to improve the electric strength of a high-voltage bushing by decreasing the maximum electric intensity. For a coaxial cylindrical bushing with radii r 0 and r m > r 0, which result in an insulation gap (r m –r 0) with permittivity e0, this problem is solved with the use of an additional layer of insulation. This layer, with permittivity e > e0, is limited by radii r 0 and r e < r m . A simple algorithm to calculate an optimal thickness of this layer was obtained; the algorithm minimizes the maximum intensity as a function of radii r 0 and r m and relative permittivity e/e0 > 1.582. The algorithm is also transformed into an algorithm of synthesis of the noted layer thickness providing minimum intensity E m . The optimal relative values of all the dimensions of a high-voltage bushing as a function of the layer permittivity and level of reduction in the intensity E m are given in a form that is convenient for practical use.