Response of Grounding Electrodes to Impulsive Currents: An Experimental Evaluation

Experimental results for the transient behavior of grounding electrodes are presented to clarify fundamental aspects of the grounding response to lightning currents. It is shown that for fast current waves, the value of impulsive grounding impedance ZP of short electrodes is smaller than its low-frequency resistance R _LF while electrodes longer than the effective length have a resistance value smaller than impulsive impedance. The values found for the ratio ZP/R _LF in the experiments are lower than those resulting from numerical simulation for electrodes shorter than the effective length.