The Impact of Different Fault Types on Touch Voltage, Step Voltage, and Ground Potential Rise

For every power system, the earthing system plays an essential role in the safety of people and equipment and ensures reliable equipment operation under normal and abnormal conditions. The power system's protection devices must be able to clear all types of faults promptly without experiencing any damage, and the earthing system must be able to timely dissipate all types of earth faults without transferring the danger to any equipment, object, or person within the vicinity of the substation, the earthing system effectively limits the touch voltage, step voltage, and ground potential rise within their tolerable limits. In this paper, a substation earthing grid was modeled, and simulations were conducted to evaluate the Impact of Line-Ground, Line-Line-Ground, and Line-Line-Line-Ground fault currents on the performance of touch voltage, step voltage, and the ground potential rise in a substation earthing grid using MATLAB/Simulink. It was observed that each fault had a different impact on the safety limits. When a fault is injected into the system, the Line-Ground fault yielded the highest voltages for touch voltage, step voltage, and ground potential rise, while the Line-Line-Line-Ground fault yielded the lowest voltages for the same safety limits.