IEC 60909-0:2016 is applicable to the calculation of short-circuit currents in low-voltage three-phase AC systems, and in high-voltage three-phase AC systems, operating at a nominal frequency of 50 Hz or 60 Hz. It establishes a general, practicable and concise procedure leading to results which are generally of acceptable accuracy and deals with the calculation of short-circuit currents in the case of balanced or unbalanced short circuits. This second edition cancels and replaces the first edition published in 2001. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - contribution of windpower station units to the short-circuit current; - contribution of power station units with ful size converters to the short-circuit current; - new document structure.