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 r₀ and r_m > r₀, which result in an insulation gap (r_m–r₀) with permittivity ε₀, this problem is solved with the use of an additional layer of insulation. This layer, with permittivity ε > ε₀, is limited by radii r₀ and r_ε < 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 r₀ and r_m and relative permittivity ε/ε₀ > 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.