More accurate modelling of earthing systems transient behaviour

Two computer models for analysis of transient behaviour of earthing systems based on the electromagnetic theory have been developed. The computer models are based on different mathematical models and different numerical techniques are applied. The first goal of the analysis is to compute the longitudinal current distribution in the earthing electrodes. Then once the currents are determined, other parameters of interest such as near fields, voltages, leakage currents, impedance, etc. may be determined by further calculations. In this paper the emphasis is given to computation of the induced overvoltages in circuits placed near the earthing systems in case of lightning. Comparison with the previous, more simplified computer models, shows that new models predict much greater induced transient voltages