Abstract: A method for detecting a short circuit on a multiphase electrical energy supply network line includes recording current and voltage sampled values and generating a fault signal upon a fault evaluation performed by an electrical protection device indicating a short circuit. Instantaneous reference voltage values are calculated from instantaneous current and voltage sampled values recorded before the short, and instantaneous comparative voltage values are calculated from instantaneous current and voltage sampled values recorded before the short and instantaneous current and voltage sampled values recorded during the short, to generate a fault signal quickly. Then a rectified reference voltage value is calculated from consecutive instantaneous reference voltage values, and a rectified comparative voltage value is calculated from consecutive instantaneous comparative voltage values.