Calculation of impulse current distributions and magnetic fields in lightning protection structures-a computer program and its laboratory validation

A circuit model and an ad hoc computer program were set up to evaluate electromagnetic interference in the vicinity of protective structures struck by lightning. This program permits the evaluation of the impulsive magnetic fields by calculating the impulse current distribution in different parts of such structures. It also allows the evaluation of the electromagnetic interference induced on susceptible victim circuits to which electric equipment may be connected. To validate the approach, a series of impulse tests was performed in the laboratory on conductive structures designed to highlight the features of the program and to make evident the dependence of the impulse current distributions on some particular phenomena that need simplified modeling, such as the effect of induced or return currents through the ground