SUBSTATION GROUNDING GRIDS INTERTIED WITH BURIED CONDUCTORS

A fault current at a substation injected into a grounding grid that is intertied with the grounding grid of another station with buried conductors, is dissipated to the ground by the grids at both the stations and by the intertie. This paper presents a direct, simple and easy to use approximate method to determine the ground resistance of the system as seen from the station where the current is injected and the ground potential rise at both the stations. A comparison of the results obtained with the approximate method and from the accurate method has been made. An expression for the length constant of the intertie as a function of the resistivity of the soil has been derived. This concept is useful to estimate the distance beyond which the two grids intertied with buried conductors will have negligible effect on each other.