Measurements of touch and step voltages adopting current auxiliary electrodes at reduced distance

Abstract

The measure of the ground resistance in a large grounding network needs placement of current electrodes at a great distance. In urban areas, where buildings' growth is adjacent to a power system, choosing suitable locations for auxiliary electrodes becomes increasingly difficult since rigorous ground resistance measures can impossibly be made. This paper suggests simplified conservative testing methods based on using one or more current electrodes at a short distance to verify the efficiency of grounding system. The touch and step voltage measures can be done with an auxiliary electrode at a reduced distance, since the error is positive, and so, the results are conservative. A simulation program has allowed the study of actual grounding systems with electrodes at a short distance. The results of the studies show the following ways to obtain conservative touch voltage measures at short distance: using one auxiliary electrode to test on the inside area of the grounding network; using more auxiliary electrodes to test on the grounding system contour zone; and placing current electrodes on particular areas to reduce error (aided by simulation program).