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Dimensioning Aspects of Horizontal Earth Grounding, With Pipe Type Electrodes

The sizing of earth grounding (EGR) is approached in the perspective of applying optimal criteria such as minimum footprint, conductive material consumption or investment costs. The soil resistivity, as a defining quantity for the dispersion resistance of the EGR, is analyzed to decide on the range of variation of its values and to estimate the maximum value, to be adopted in the design. The calculation relations are grouped in the sequence of their use, thus composing the complete physical model of the studied application. The known limited indications of the HEG utilization coefficient are compensated by proposing a linear relation for the calculation of this quantity as a function of the electrode length and the in-plane distance between neighboring parallel electrodes. Due to the non-linear physical model of HEG, it was necessary to develop an algorithm for the successive identification of the computational sizes, which is the basis for the determination of the triad electrode length-electrode number-distance between electrodes. The values of the dispersion resistance of the interconnecting conductor between the electrodes being important for the determination of the total dispersion resistance of the HEG, its calculation was included in the physical model of the EGR. Using the complete physical model of the HEG, a series of sizing runs are made to highlight the possibilities of applying the optimality criteria in setting the final values for the HEG specific quantities, under the mandatory condition of bringing the dispersion resistance of the EGR within the allowed range. Two of the optimal criteria represented by the minimum footprint area or mass of metallic materials were tested on a series of concrete data in order to determine areas of interest for future studies.