Using EMTP for evaluation of surge current distribution in metallic gridlike structures

This paper presents a study on the utilization of EMTP (EMTP used for this paper is GNU ATP/Mingw32 running in WINNT OS) in calculating the lightning current distribution in the metallic structure of a building. The structure is modeled as a network of π-circuits and represented by three parameter matrices, [R], [L], and [C]. With the modifications in EMTP, EMTP can compute the current distribution in the structure in either frequency domain or time domain during a direct stroke to a structure or an indirect stroke near a structure. Subsequently, the impulsive magnetic filed inside the structure can be evaluated. The accuracy of this method is verified by a laboratory experiment. A 10 m×10 m×10 m structure is also constructed in the paper for the illustration of both lightning current and magnetic field evaluations. The results show that EMTP is capable of analyzing lightning currents in the metallic gridlike structure of a building.