Measurements of partial discharges by computer and analysis of partial discharge distribution by the Monte Carlo method

The mechanism of partial discharge (PD) occurring in the CIGRE Method II (CM-II) electrode system, which is a representative closed-void model system is discussed in the context of a computer-aided PD measuring system. Measurements of PD are made for the CM-II electrode system. Effects of the pressure and gas inside the void on the PD are examined. Taking into account the experimental results, a model for the PD mechanism is proposed. This model assumes that the statistical time lag of discharge depends on the overvoltage and that the residual voltage depends on the PD magnitude. A Monte Carlo simulation of the PD distribution is made on the basis of this model. The computed results agree well with the experimental data and the appearance of swarming pulsive micro discharges. The physics of the model are discussed.>