A Parametric Analysis of Fault Current Division between Overhead Wires and Substation Grounding Systems

C. Li, X. Wei (PRC), Y. Li, and F.P. Dawalibi (Canada)


Grounding System, Fault Current Division Factor, Grounding System Resistance, Overhead Ground Wires, Tower Resistance


This paper presents a parametric analysis of the fault current distribution between a substation grounding system and its overhead ground wires and their effects on the grounding systems performance. The influence of the following variables are studied: the resistance of the substation grounding system, the characteristics of the shield wires, the number and the length of the transmission lines connected to the substation, the terminal types (i.e., power source and non-power source terminals), soil resistivity, and power line configurations. It is concluded that the fault current division factor is dramatically affected by the substation grounding resistance, the shield wires conductor characteristics, and the number of transmission lines while it is less influenced by the soil resistivity along the transmission lines and tower resistances. It is difficult to estimate the current division factor for a practical case. The only way to compute accurately the current division factor is to analyze individual cases based on the existing conditions with proper software tools.

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