Análise de resposta de uma malha de aterramento submetida a correntes impulsivas por meio de resultados experimentais.

Abstract

In this work, an experimental assessment of a ground grid behavior when subjected to impulsive currents was performed, both in the time and in the frequency domain, analyzing transient impedance and pulse impedance (time domain), and harmonic impedance (frequency domain) relative to the front time, fall time and amplitude of the current injected into the ground grid under test, in order to evaluate its quality under high frequency applications, and also validate the obtained results by using computer models in the time and frequency domain. For this purpose, four different pulse generator settings were used, resulting in four distinct impulsive current wave forms, wherein each wave form was injected into 3 different amplitudes. The results showed that when the analysis variable was the injected current amplitude, the impulsive impedance had no significant variation. It was also shown that when the analysis variable was the front time of the applied current signal, the impulsive impedance varied inversely proportional to the front time of the applied current signal. When the harmonic impedance module related to the three impulsive current amplitudes injected was analyzed, it was concluded that: the harmonic impedance module had no significant changes compared to the injected current amplitude, to the current waveforms with the same front time. When the harmonic impedance module related to the four waveforms was analyzed, it was observed that: for all studied cases, the harmonic impedance module is constant for frequencies below 100 kHz and, above this frequency, the module had its value increased, reaching its highest value at around 1 MHz. The phase of the harmonic impedance had no significant changes compared the amplitude of the injected current. When we analyzed the phase of the harmonic impedance with respect to the waveforms observed that electric grounding is predominantly inductive behavior.