The effects of increased fault current on the existing substation grounding system : A case study
Date
2015-05-26
Authors
Mapane, Mohau
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Abstract
The aim of this research is to investigate the effect of increased fault current on an existing
substation grounding system. Increased load demands because of the new customers connecting
on the existing network or reconfigured network, power flows on the transmission and
distribution assets will increase, which will in turn trigger the increase in fault current levels,
both three-phase and phase-to-ground, throughout the power system. The protection that ground
grids provide against step- and touch potentials is only good up to the expected level and
duration of ground fault currents, as originally communicated in the design phase. A case study
is presented in this research project to investigate the effects of increased fault current on the
existing Ruighoek distribution substation grid. It is found that, the ground potential rise and
touch potential are aggravated by the increased fault currents. And by increasing the area
occupied by the ground grid and decreasing the horizontal spacing of parallel conductors, stepand
touch potentials are improved to safe limit as per IEEE Std. 80-2000.