A Study on the Transient Ground Impedance Modeling for Rod-type Grounding Electrodes by Frequency and Time Domain Characteristic Tests

Grounding system insures a reference potential point for electric devices and also provides a low impedance path for fault currents in the earth. The ground impedance as function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. Copper and concrete rod electrodes are the most commonly used grounding electrode in electric distribution systems. In this paper, the ground impedance of copper and concrete rods has been measured by frequency and time domain characteristic tests. An equivalent transfer function model of the ground impedance is identified from the measured values by using ARMA method and evaluated by comparing conventional grounding impedances.