Influence of bulk dielectric polarization and void geometry upon PD transients

The induced charge arising from a partial discharge consists of a component associated with the actual space charge in the void, and one related to changes in the polarization of the bulk dielectric. These changes are brought about by field produced by the space charge. influence of the void geometry upon the polarization component of the induced charge is examined for a heterogeneous bulk dielectric system. It is demonstrated that the relative magnitude of this component may either increase or decrease, depending on the ratio of the dielectric permittivities and within which dielectric the void is located. The magnitude of this effect is also dependent upon the prolateness/oblateness of the void geometry and on the orientation of the void.