Simulation of partial discharges in voids in insulating materials

Partial discharge literature reports that in new voids, the current pulses generated by partial discharges have short rise times, last only a few nanoseconds and generally have a great amplitude. After a given ageing, when the walls are oxidized, the current pulses have a longer rise time, a longer duration and a lower amplitude. The paper presents results obtained for the current pulses by a computer simulation of the equivalent electrical circuit of the whole system (comprising a pulsed power supply, the void and its surrounding dielectric) with ``reasonable'' ionization coefficients for the development of the partial discharges. Special attention is paid to the role of the void size in the discharge development.