FDTD analysis of the three dimensional magnetic field distribution inside a building under direct lightning stroke

When lightning strikes the building the lightning electromagnetic pulse (LEMP) will generate in its internal three-dimensional space, and it will cause different intensity transient over-voltage and over-current in various electrical and electronic device through conduction, induction and coupling, thus affecting the safe and reliable operation of the equipment. In order to study the indoor three-dimensional magnetic field environment caused by lightning stroke, this paper adopts FDTD method to calculate and analyze the lightning current distribution in steel bars of the structure when the roof corner struck by lightning. Subsequently, the waveforms and the distribution features of the three-dimensional magnetic field are calculated. The conclusions on the indoor lightning EMC design and lightning risk assessment have important engineering significance.