Shielding of Pulsed Magnetic Field on Lightning Down-Conductors

Abstract:
In case of steep lightning currents in lightning down-conductors, transient magnetic fields occur, which can cause damaging indirect lightning effects in structural installations. In particular, overvoltages may be imposed on electrical installations or electronic equipment. Thin metal shielding screens with small lateral extent close to lightning down-conductors should significantly reduce the magnetic pulse fields behind this screen. Calculations, simulations and scaled experiments show the achievable shielding effect, which results in a significantly lower magnetic field strength, or magnetic flux density respectively. Due to eddy currents in the shielding screen, the front slope of the pulse magnetic field is also reduced and at the same time the field pulse duration is extended.