Characteristics of the induced currents in horizontal conductors due to a nearby lightning strike

A nearby lightning strike can induce significant currents in long horizontal and tall down conductors. Although the magnitude of the current in this case is much smaller than that encountered during a direct strike, the probability of occurrence and the frequency content is higher. In view of this, appropriate knowledge of the characteristics of such induced currents is relevant for the interpretation of recorded currents. Considering these, the present paper discusses a modeling procedure that permits simulation of lightning-induced voltages or currents on overhead lines due to a nearby lightning strikes. The hypothesis of perfect conducting ground, generally adopted in studies on the subject, is discussed in order to better assess the validity of the simulation results. In this paper, homogeneous non-perfect ground is also investigated for the influence of lightning-induced voltage. The procedure for analyses of the voltages induced on an overhead line by a nearby lightning return stroke with a striking point in an unequal distance from the line terminations. The analysis shows that lightning induced voltages depend on the soil conductivity.