Impulse impedance of the horizontal grounding electrode: comparison of the theoretical antenna model approach and experimental analysis

Abstract

The paper deals with the comparison of two methods for the calculation of the impulse impedance of the horizontal grounding electrode defined as a ratio of maximum values of induced voltage and current at the injection point on the electrode. The current distribution along the electrode is calculated using the antenna theory based model featuring the thin-wire approximation and corresponding Pocklington integro-differential equation in the frequency domain. The equation is solved using analytical techniques with the exact solution of the integral over Green’s function. The scattered voltage is subsequently calculated from the Generalized Telegrapher’s equation. On the other hand, experimental technique based on direct in situ impulse impedance measurements is applied on the actual horizontal electrode based grounding system. The results obtained via different methods agree satisfactorily, proving that the proposed model can be used to estimate the impulse impedance and, furthermore, complement the understanding of the grounding electrode early time behavior by providing the transient impedance data.

Keywords:

• Analytical modeling
• electromagnetic transients
• experimental technique
• grounding electrode
• impulse impedance