Effects of impulse polarity on grounding systems

In earlier paper, experimental results of 1-rod, 2-rod and 3-rod electrodes under high magnitude impulse currents of positive polarity were presented. In the paper, it was noticed that lower reduction of impulse resistance from its steady-state ground resistance value, RDC in large size of grounding electrodes (3-rod electrodes). The paper also showed a significant increase of current rise time in 3-rod electrodes, for current magnitudes of below 1.5 kA, indicating an inductive effect in large grounding electrodes. The results on the performance of grounding systems for increasing number of rods were only presented for positive impulse polarity.