White Papers

Grounding Considerations for Transmission

By Jared Mraz, Aaron Findley, David Lewis, Joe Mooney


The purpose of this paper is to identify transmission line design and grounding configurations for which tower footing resistance may have a significant impact on resistive fault coverage requirements and warrant additional study. This paper reviews the fundamental concepts of tower grounding from a line relaying perspective and documents the relative impacts of tower grounding resistance. The apparent impedance of various overhead shield wire designs, the resulting fault current distribution among towers, and typical structure grounding approaches are addressed in this report. Apparent impedance calculations and simulations of typical transmission line grounding configurations will be presented.

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This paper was presented at the 2018 Western Protective Relay Conference