Estimation of discharge inception voltages at different pressures in the ambient medium of N2

In this paper we report a technique for estimating the partial discharge (PD) inception voltages in case of discharges occurring at the interface as well as in voids in the ambient medium of nitrogen gas (N₂). Since occurrence of partial discharge is a phenomenon dependent on thickness of insulation, pressure in the gap, shape of void or cavity etc; all these parameters have to be taken into account. The computed values are valid in the pressure range of 0.067 kPa to 101.333 kPa. Computations are accurate to plusmn 3.5 % in the/tf´range of 0.0313 - 1400 kPa-cm. These computations are useful in understanding discharges in the insulation system of cables, capacitors, bushings or epoxy cast equipment which are dried and impregnated at low pressures and may contain gas pockets at sub-atmospheric pressures. These computations are also important and useful for high altitude insulation design and spacecraft insulation.