Modelling of partial discharge activity in different spherical cavity sizes and locations within a dielectric insulation material

The pattern of partial discharge (PD) occurrence at a defect site within a solid dielectric material is influenced by the conditions of the defect site. This is because the defect conditions, mainly its size and location determine the electric field distributions at the defect site which influence the patterns of PD occurrence. A model for a spherical cavity within a homogeneous dielectric material has been developed by using Finite Element Analysis (FEA) software. The model is used to study the influence of different conditions of the cavity on the electric field distribution in the cavity and the PD activity. In addition, experimental measurements of PD in spherical cavities of different size within a dielectric material have been undertaken. The obtained results show that PD activity depends on the size of the cavity within the dielectric material.