Lightning induced transient voltages in presence of complex structures and nonlinear loads

EMI induced in electronic circuits inside a building due to a lightning flash can be caused by either a direct strike to the lightning protection system or or by an indirect discharge in close proximity. This paper deals with the induced transient voltages on nonlinearly terminated metallic loops inside a building due to an indirect lightning strike. The conductive parts of the building (such as reinforcing bars in walls and floors, metallic beams), the lightning protection system, and the loops are simulated by an electric field integral equation in the time domain, with the nonlinear loads by a system of nodal equations. These two sets of equations allow a solution to be determined completely in the time domain. The proposed technique is validated by comparison with other referenced numerical techniques. Some results which show the effects of the conductive structural elements of the building on the induced transients are presented.