Improved Methodology for High-Frequency Low-Current Measurement of Grounding Rod Impedance

The high-frequency behavior of grounding rods is a major concern in several applications where high-frequency currents are involved, such as lightning currents or transient phenomena. Some measuring systems of high-frequency impedance of grounding rods are now available. However, the widely used method is the fall of potential using a three-rod method configuration such as in low-frequency measurements. A special spherical real-scale setup presented in this paper shows the influence of the ground current distribution on the impedance measurement. This effect is not relevant for the usual low-frequency measurements. Thus, careful attention should be paid to current distribution before concluding on the behavior (capacitive, inductive) of a grounding system.