Circuit-based model grounding electrode considering frequency dependent of soil resistivity and relative permittivity

Abstract

This paper presents the simulation of circuit-based horizontally oriented grounding electrodes with the consideration of frequency dependence of soil resistivity and permittivity. The frequency dependent circuit parameters were determined by the equations given by Sunde and Dwight, while the frequency dependent properties (soil resistivity and relative permittivity) were modeled according to Scott model. Results obtained show that the voltage response is highly affected by the soil resistivity, especially at high soil resistivity value, which in this study, the highest value is 2000 Ωm. This work also considers the front time of the current to study the effect of current front time to the response, and it was found that the faster the current front time, the more significant difference of peak voltage between frequency dependent and frequency independent models is obtained. Obviously, the current circuit-based model (frequency independent model) tends to provide overestimated results. Therefore, the effect of frequency on the soil resistivity and relative permittivity should not be neglected when determining the transient performance of grounding electrode in order to obtain accurate results.