Characteristics of the conventional grounding impedance based on the dispersed impulsive current of the horizontal ground electrode in two layer soil structure

초록

When surge currents caused by lightning strikes are injected into the grounding system, the transient response of grounding system is much different with the ground resistance. Except for the soil ionization phenomena around the grounding electrode, it is widely known that the transient performance of grounding system is deteriorated under surge currents. It is necessary to design and install grounding systems of lightning protection systems with considering characteristics associated with surge currents. This paper deals with the impulsive ground current rate dispersed into the soil and the conventional grounding impedance according to the length of horizontal ground electrodes widely used in transmission tower and lightning protection of power systems. As a result, the grounding impedance at the injection point with low resistivity shows the low value for the same length of horizontal ground electrodes. The fast fronted impulse current is much dispersed near the current injection point. These results provide the reasonable technique for the selection of location and conditions of the grounding electrodes to reduce the transient potential rise against surge currents.