The insulation used for a high voltage application is one of the most important components in any design because breakdown of the insulation may cause total failure of the whole component. The electrical insulation system is subjected to high electrical, mechanical and thermal stresses which can age and degrade the insulation to the point where partial discharges (PD) can become a regular occurrence ultimately leading to total breakdown. Detection and analysis of PD activity is therefore important to ensure the health and lifetime of any high voltage asset.
Partial discharge is a discharge event that does not bridge the electrodes within an electrical insulation system under high voltage stress. In high voltage components, the measurement of partial discharge is used in the performance assessment of an insulation system. Through modelling and measuring the discharge process a better understanding of the phenomena may be attained. This project describes the development of a mathematical model describing partial discharge in a spherical cavity and ellipsoidal cavity within a homogeneous dielectric. The model developed is used to study the influence of the applied frequency on partial discharge activity and also the influence of the cavity size and cavity location within the insulation material on partial discharge frequency dependent activity. The simulation results can then be used within insulation diagnostics to assist in the assessment of the performance of the insulation system.