Analysis of Transient Grounding Resistance of Four Simple Earth-Termination Systems

The impulsive discharging efficiency of four kinds of simple earth-termination systems is studied. The transient grounding resistance (TGR) of the earth-termination systems with two different impulse current is calculated using FDTD method. The corresponding waveforms of TGR in time-domain under different conditions are illustrated. The following results can be obtained: adding vertical earth electrodes to the horizontal ones can reduce the TGR and the value of TGR decreases with the increasing number of vertical earth electrodes when the space between the vertical earth electrodes is greater than twice of its length; there is a dynamic process for the transformation of TGR and it needs some time to become constant; the impulse current's rise time is shorter, its width is narrower and the frequency range is wider, the maximum value of the TGR is higher and the time when TGR become constant is longer.