Effects of Potential Interferences between Ground Electrodes on the Resultant Ground Impedance

초록

This paper deals with the resultant ground impedance depending on potential interferences between ground electrodes. When installing ground electrodes, the way of installing ground electrodes in parallel is commonly used to satisfy the required ground resistance. When ground currents flow into each ground electrode, the resultant ground impedance is increased by the potential interferences. In order to analyze the effect of the mutual potential interference on the ground impedance of grounding system consisted of multi-ground electrodes, the ground impedances of vertical ground electrodes installed with a regular n-polygon and 3 and 4-arms star horizontal ground electrodes were experimentally investigated. Also the ground impedance of ground electrode systems is calculated by using the distributed parameter circuit model, and the frequencydependent soil resistivity is taken into consideration in simulation. The ground impedances both with and without the potential interferences are calculated. As a consequence, the accuracy of the simulation methodology was evaluated by the comparison between the measured and simulated results, and the results showed a good agreement between the simulation and the experiment. Also it was found that the effect of potential interference on the ground impedance is directly associated with the frequency-dependent ground impedance and is pronounced in low frequency.