Characterization of horizontal earth electrodes: Variable frequency and impulse responses

Grounding systems such as vertical and horizontal electrodes, and grids are installed in the soil to mitigate against the effects of system faults and lightning surges. Their main function is to dissipate lightning and fault currents into the earth without generating any hazardous potential differences between different contacts points of grounded structures and the earth that may be bridged by people or sensitive electrical equipment. In this investigation, field tests applying both low voltage impulse and variable frequency energisations to a horizontal earth electrode installed in a low resistivity soil medium have been carried out. The frequency response is determined from the AC variable frequency test over frequency (50Hz up to 1MHz). Numerical models of the tested electrodes were simulated considering the effect of soil parameters and the results were compared with field tests measurements.