Transient Grounding Impedance of Electrode Elements for Grounding Mat

This paper presents the surge responses of the grounding system using the scaled electrode models experimentally. To examine how the construction of the electrode elements affects the surge impedance, we selected the following electrode element models, a linear one, a straight one with linear branches, curved branches, and the complex electrode made by these elements. It was investigated into their surge responses from the condition of very high soil resistivity to low one simulated by the immersion of the model into the electrolyte medium. The experimental results showed that the impulse impedance decreases if the appropriate length of the electrode is connected to the end conductor of the mesh to divide current. It is also displayed the remarkable effect of the impedance reduction in the combination of the electrode elements simulated to the grounding mat. Besides the evaluation of the impulse impedance in time domain, we also calculated the frequency characteristic of the electrode model by Discrete Fourier Transform. In frequency domain, we obtained the similar relationships in order of the magnitude of the impedance with time domain.