Interception probability of a protective rod in the presence of an object on the ground

In this paper, the influence of the height and position of a grounded object on the interception probability of a protective rod is experimentally investigated under standard lightning impulse voltages of positive polarity. By using a 77 cm energized rod-plane gap the interception probability of a protective rod of different heights is calculated when putting another object on the plane. It was found that the discharge interception probability of the protective rod is strongly affected by the height and position of the grounded object. The time to breakdown and the instantaneous breakdown voltage are two parameters deduced from experimental tests. It was noted that the discharge makes more time to occur when moving the protection far from the energized rod. The insertion of another rod reduces the time to breakdown. The discharge always happens during the tail of the applied impulse voltage making that the variation of the instantaneous breakdown voltage decreases with increasing the separation distance between rods.