Analysis on Shielding Effect of the Grounding Electrodes under Impulse-Current

Generally, the flow of a lightning impulse current from a grounding electrode into ground is a very complicated process determined by many factors. In order to analyze the mechanism of the impulse current dissipating in the earth from grounding electrode, the experiments that had carried out by other authors almost used a single horizontal grounding wire or vertical grounding rod for sake of simplicity. However, in practical conditions, most of the grounding systems are constructed of grounding electrodes with branches in different directions. In this paper, basing on the principle of dimensional similarity, impulse simulation experiments are performed on the common ground electrodes with conductor branches. We focus on analyzing the impulse current dispersal regularity of different branches when injecting at one point. Comparing with the leakage current distribution of a single ground electrode, it is found that the leakage currents along the branches increase with the distance to the current feed point, and the more conductors near the injection point, the more uneven the leakage current distribution is. This work indicates that shielding effect should be taken into account when analyzing the impulse characteristics of grounding electrodes.