Approach to partial discharge development in closely coupled cavities embedded in solid dielectrics by the lumped capacitance model

The use of the typical ABC equivalent circuit for one cavity in solid dielectrics for internal partial discharge modelling has been common practice for many years. The introduction of an equivalent circuit for two closely coupled cavities permits the investigation of the interaction between discharges in such cavities in a solid dielectric when it is stressed by high AC voltages. In this model circuit, cavities and solid dielectric parts are represented as lumped capacitances, while the resistance and the inductance of the test voltage source are taken into consideration. By using a version of the Electromagnetic Transients Program (EMTP), the waveforms of the voltage across the two cavities, as well as those of the voltage across the neighbouring parts of the solid dielectric, have been traced, and the transient voltage stressing of these parts has been analysed for repetitive discharges in the two cavities.