Impact of soil-parameter frequency dependence on the response of grounding electrodes and on the lightning performance of electrical systems

This brochure addresses the frequency dependence of soil resistivity and permittivity. It discusses the physical reasons of this dependence and describes the methodologies used for the measurement of the variation of these parameters with frequency in the range of lightning currents’ components. The impact of this frequency dependence effect on the lightning response of grounding electrodes, on the lightning performance of transmission lines and on the induced voltages is determined. The brochure recommends “when” and “how” to take this effect into account and provides analytical expressions for that purpose.