Numerical analysis of the electric field in and near a bubble located in one dielectric in series with another

Three-dimensional (3-D) numerical analysis was performed to quantify the electric field in and near a bubble located in single dielectric and one of two dielectrics in series, and especially to have an insight into the quantitative characteristics of the influence of gaseous defects on the field when the void locates in a high-permittivity liquid in series with polymer film. The results show that the field in the bubble predicted by onedimensional (1-D) treatment of the defect in single dielectric will be significantly greater (about 30% to 2 times) than that given by 3-D model; and for a bubble in one dielectric of very large permittivity in series with another, the field by 1-D treatment is dramatically (more than an order of magnitude) higher than the 3-D results. These data indicate that the influence in field of gaseous defects on the partial discharges and/or breakdown behavior of liquid and solid dielectrics may be overestimated from ten´s percent to several times, or even more than an order of magnitude when the defects locate in high-permittivity dielectric in series with low-permittivity one.