A study on the partial discharge characteristics according to the distribution pattern of voids within an insulation

The electrical field, partial discharge inception voltage of the insulating materials, where two voids rather than a single void are located, were successfully obtained by numerical simulation. Our numerical results, obtained by both 2D and 3D simulation, agree with the experimental results. The results from numerical field analysis and experiments show that the electric field within the voids decreases as they are more serially arranged, which accordingly results in an increase of partial discharge inception field (PDIF) much higher than that of the single void model. With parallel arranged voids, the PDIF is almost the same as that of single void model. On the other hand, the AC breakdown strength decreases as voids are arranged more serially, which is an expected result when considering the reduction of the effective insulation thickness. For parallel voids, this effect cannot be noticed.