Lightning-Induced Current in a Cable Buried in the First Layer of a Two-Layer Ground

Abstract

This paper analyzes the effect of a two-layer ground on the current induced in the shield of a buried cable due to lightning flashes. Each layer is assumed to be horizontal, homogeneous, isotropic, and having its own electrical parameters: conductivity, permittivity, and permeability. The inducing horizontal electric field is calculated for the incident azimuthal magnetic field and it is used for the calculation of the induced current. The calculation method is validated by comparing its results with results published in the literature. The currents induced in the shield of a buried cable by typical return-stroke current waveforms are calculated. The results show that the induced current waveform is initially determined by the first layer but, for later times, it follows the current that would be induced if the ground was homogeneous and had the characteristics of the second layer.