An experimental study of short-circuit currents on a low-voltage system

An experimental study of short-circuit currents on a low-voltage power system was conducted to determine whether the fault current level can be accurately predicted from supply impedance measurement at supply frequency. The related question of whether the power system can be modeled by a series X-R impedance for the purpose of fault-level calculation is also considered. A practical method of measuring the supply impedance of a potentially unbalanced power system is presented. The method requires only RMS measurements to be made when real, reactive, and open-circuit loads are applied