Influence-Factor Analysis and Parameter Calculation of Soil Discharge and Recovery Characteristics Under Successive Impulse Currents

Lightning usually contains multiple return strokes. Under multiple impulse currents, the main characteristics of soil media are not only those of breakdown but also those associated with recovery of electrical parameters. In this paper, the discharge recovery characteristics of soil under successive current pulses and the influences of various main factors are studied. The structural characteristics of soil subject to successive impulse discharges are analyzed from X-ray images taken during discharges. On the basis of experimental results, the modification method of soil resistivity under successive impulse currents is discussed. Depending on the conditions, these results show that the peak value of the impulse current and the water content of the soil have a significant effect on the rate and duration of recovery. However, the effect of soil salt content on recovery is not significant. Under successive impulse currents, the electrical characteristics of soil take about tens to hundreds of milliseconds for full recovery.