Apparatus for swift determination of fault in electric power system

PURPOSE: A high speed accident determining device is provided to rapidly determine whether an accident is happened or not by controlling the size of accident reference voltage of a current value, a current 1st differential value, and a current 2nd differential value. CONSTITUTION: A current transformer(800) detects a current supplied to an electric power system. A current determining unit(810) compares differential voltage of current detecting voltage of the current transformer with reference voltage. A accident determining unit(850) determines whether an accident is happened or not by using a comparison signal of the current determining unit. The accident determining unit creates a trip signal in case the accident is happened. A plurality of light sensors is installed in a site when an electric arc accident is happened and emits light.