Influence of bulk dielectric polarization upon PD transients: Effect of multiple dielectric layers

A physically valid theory of partial discharge transients has been developed using a field-theoretical approach. The theory is based upon the concept of charge induced upon the detecting electrode by the partial discharge. This induced charge can be resolved into a component associated with the actual space charge in the void and one related to changes in the polarization δP&oarr; of the bulk dielectric.

These changes are brought about by changes in the field external to the void, which in turn are due to the void space charge. The magnitude of the induced charge component due to δP&oarr; is discussed in relation to a three-layer bulk dielectric.