Analysis of the conventional grounding impedance of counterpoise

초록

The conventional grounding impedance of a counterpoise is calculated by using the distributed parameter circuit model as a function of length of the counterpoise, and it is embodied in the distributed parameter circuit model by using the EMTP program in each length. The adequacy of the distributed parameter circuit model is examined and verified by comparing the simulated and the measured results. The conventional impedance of the counterpoise is analyzed for the first short stroke and subsequent short stroke currents. As a result, the simulated results show that the length of the counterpoise having the lowest conventional impedance is of importance and not the entire length over which the ground resistance is lowest. The faster the time to current peak when the injected currents flow through the counterpoise is, the shorter is the length of the counterpoise which has the lowest conventional impedance. Therefore, it is necessary to compute the length of the counterpoise which satisfies both the low conventional grounding impedance and suitable ground resistance in order to design and install counterpoises economically.