ABSTRACT
Electric power systems are often grounded, that is to say “intentionally connected to earth through a ground connection or connections of sufficiently low impedance and having sufficient current-carrying capacity to prevent the buildup of voltages which may result in undue hazard to connected equipment or to persons” (IEEE Std 100, 2000). Grounding affects the dynamic power-frequency voltages of unfaulted phases, and influences the choice of surge protection. Also, the tower footing impedance is an important specification for estimating the transient voltage across insulator strings for a lightning flash to an overhead ground wire, tower or phase conductor with surge arrester.
