Electric Field Enhancement in an XLPE Insulated Power Cable Containing Different Voids and Portrusions

Abstract

This paper investigates the electric field enhancement created due to the presence of different types of voids and protrusions separately as well as simultaneously inside a polymeric insulated power cable. XLPE insulated power cables are used extensively in power systems as a preferred choice over traditional gas filled and impregnated paper insulated power cables. However, the presence of voids and cavities inside an insulation or on the semiconducting layer is unavoidable leading to an excessive field enhancement inside an insulation. This inevitably results in internal partial discharge and in a long run the failure of the entire cable insulation. For this contribution, the simulation of electric field is done on a two dimensional (2-D) model of a standard 22 kV XLPE insulation using Finite element analysis considering the effect of different voids and protrusions that may be present inside an insulation. Investigations reveal that the cable containing ellipsoidal protrusion with a cylindrical and elliptical void leads to a maximum field enhancement at the position of the void and at the surface respectively which is vulnerable for cable insulation.