Applicable to the calculation of short-circuit currents:
- in low-voltage three-phase a.c. systems
- in high-voltage three-phase a.c. systems
operating at a nominal frequency of 50 Hz or 60 Hz.
Systems at highest voltages of 550 kV and above with long transmission lines need special consideration.

The contents of the corrigendum of February 2002 have been included in this copy.