Characteristics of Soil Ionization around a Ground Rod under Impulse Voltages

The study described the results of experiment on electrical and physical characteristics related to soil ionization around a ground electrode to which impulse voltages were applied to coaxial circular electrode system, simulated by the ground rod or the horizontally buried ground electrode. Ground resistance was significantly reduced by soil ionization caused by impulse voltage in which the voltage-current characteristic curve ( curve) appeared as ∞-shape of a cross-closed loop. According to the increase of impulse current through a ground electrode, the equivalent soil resistivity was reduced, but the delayed time to the maximum of the equivalent radius of the ground electrode was increased. As soil ionization progressed, average progress speed increased proportionally, according to the increase of peak current.