The Current Generation Mechanism in the Earth Lines of a Building in TT System Struck Directly by Lightning

Surge protective devices (SPDs) are installed between the neutral and earth lines at the power substation in a TT system to protect the equipment in a building struck directly by lightning. In this case, when operating the SPD, the wiring system of the low-voltage distribution line is a TN system. Using this system, our previous study clarified that the overvoltage generated in the distribution board on each floor was caused by the loop impedance of earth wiring connected to the distribution board. In this article, we elucidated the electromagnetic generation mechanism of the current flowing in the protective earth line that formed the wiring loop.