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Walter Luiz Manzi de Azevedo
Faculdade de Engenharia Elétrica e de Computação, UNICAMP, Campinas, SP
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José Luciano Aslan D’Annibale
Faculdade de Engenharia Elétrica e de Computação, UNICAMP, Campinas, SP
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Anderson Ricardo Justo de Araújo
Faculdade de Engenharia Elétrica e de Computação, UNICAMP, Campinas, SP
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Jaimis Sajid Leon Colqui
Faculdade de Engenharia Elétrica e de Computação, UNICAMP, Campinas, SP
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José Pissolato Filho
Faculdade de Engenharia Elétrica e de Computação, UNICAMP, Campinas, SP
Keywords:
transient response, lightning, ground potential rise, frequency-dependent soil, inclined grounding electrode
Abstract
This paper investigates the influence of the inclination angle (in relation to the vertical axis) on the harmonic grounding impedance (HGI) of four arrangements of rods and on the performance of the Ground Potential Rise (GPR) generated on those electrodes subjected to a lightning strike. A full-wave electromagnetic software FEKO using Method of Moments (MoM) is utilized for the analysis where the soil parameters (resistivity and relative permittivity) are modeled using the recommended formulas in the CIGRÈ WG. C4.33 (2019). The analysis is carried out for three soils with low-frequency resistivities (ρ0) of 100, 500 and 1,000 Ωm where the HGI is computed for a frequency range of 100 Hz to 10 MHz assuming the inclination angles of 0◦, 15◦, 30◦, 45◦ and 60◦. The transient GPR is assessed for a 1 A-0.25/100 µs lightning current. Results demonstrated that a significant reduction of the HGI is obtained when the inclination angle increases for a certain electrode arrangement. As a consequence, the transient GPR waveforms present significant mitigation for each grounding system which can be obtained only by setting distinct topology and inclination of the rods.
