Experimental analysis of horizontal grounding wires buried in high-resistivity soils subjected to impulse currents

Abstract

• Experimental response of grounding wires in high-resistivity soils is presented. • Grounding impulse impedance is lower than resistance for higher resistivities. • Experiments show relevant influence of frequency dependence of soil parameters. • Influence of increasing the front-time on impedance depends on electrode length. This paper presents experimental results of the ground potential rise (GPR) developed by grounding wires buried in high-resistivity soils and subjected to impulse currents. A large experimental dataset is presented, comprising grounding wire lengths ranging from 10 m to 50 m, buried in soils of resistivities between around 1100 Ωm to 1600 Ωm, and subjected to impulse currents with front-time ranging from around 1.2 μs to 7 μs. The experimental results further confirmed some important aspects regarding the lightning response of grounding electrodes buried in high-resistivity soils, namely the influence of the frequency dependence of soil parameters and the value of impulse impedance lower than the grounding resistance for electrodes shorter than effective length. Comparison between experimental and simulated results reinforces the need to consider the frequency-dependence of soil parameters for obtaining accurate results of the lightning response of grounding systems buried in poor conducting soils.