Simposio Internacional sobre la Calidad de la Energía Eléctrica - SICEL

This paper presents some preliminary experimental results developed by the authors regarding the response of grounding electrodes to impulsive currents. These results were obtained from the injection of fast current waves into the soil through some simple electrode arrangements. The most important finding is that the Impulse Coefficient given by the ratio of Impulsive Grounding Impedance and Low Frequency Grounding Resistance may present values lower than unity for lightning currents, even in the absence of soil ionization. This result is relevant since it contradicts a very usual assumption in Lightning Protection Field.