A Complete Field Analysis of Substation Ground Grid By Applying Continuous Low Voltage Fault

A field investigation of a ground grid using continuous 60Hz power source was carried out in a 115/12kV distribution substation. Field measurements included the grid potential rise (GPR), surface voltage gradients and distribution of the fault current. Four different fault locations were investigated to determine the worst fault and its location. By scaling up the measured data, safety-related grounding parameters corresponding to a full scale fault, are determined. Measured data is compared with computer calculated data. The field test presented in this paper can be a valuable tool for utilities to analyze ground grids for assessing safety and for verifying the design method by comparing the design parameters with the measured data.