Transformer bushings — Modelling of electric field and potential distributions within oil impregnated paper with single and multiple spherical cavities

摘要

The majority of power transformer high voltage bushings today are of the condenser oil impregnated paper (OIP) type. These bushings have a series of dielectric layers with conductive foils in between each layer, which improve electric field uniformity. This paper studies the electric field and potential distributions within an OIP system containing single and multiple air filled spherical cavities. Simulations are made using the finite element method (FEM) for a plate-to-plate and a cylindrical geometry. The numerical models studied use typical parameters from OIP condenser bushings. The results show the distribution variation with cavity size, cavity location and the effects of clustered cavities. It is expected that the results will provide an improved understanding of how to model faults within OIP bushings.