IEC TR 60909-4 pdf download.Short-circuit currents in three-phase a.c. systems 1 General 1.1 Scope and object This part of IEC 60909 is a technical report intended to give help for the application of IEC 60909-0 for the calculation of short-circuit currents in 50 Hz or 60 Hz three-phase a.c. systems. This technical report does not include additional requirements but gives...