Investigação teórico-experimental sobre a resposta de aterramentoselétricos frente a correntes de descargas atmosféricas

Abstract

This work presents the results of an experimental investigation about the behavior of grounding electrodes subjected to low intensity impulsive currents, whose waveforms are similar to the lightning ones. Basically the results consist in the response of electrodes, in terms of developed voltage, to the injection of impulsive currents, considering soils with high and low resistivity values. Interesting results were obtained, which might be useful to allow evolving the understanding of the transient response of grounding electrodes. They might be also applied to validate theoretical models intended to predict such response. The investigation included experimental developments, such as the implementation of an impulse generator for application of the test currents and the systematic tests consisting in impressing impulsive currents to different electrodeconfigurations for measurement of the quantities of interest. Two main contributions were derived from the results. First, it was foundthat the capacitive effects in the soil are more relevant than usually assumed. Also, for the evaluated cases, always the impulsive grounding impedance had a value lower than the low frequency resistance in both conditions of soil resistivity when the electrode is shorter than the effective length.