IEC 60909-3 pdf download Short-circuit currents in three-phase AC systems – Part 3: Currents during two separate simultaneous line-to-earth short circuits and partial short-circuit currents flowing through earth 1Scope and object This part of lEC 60909 specifies procedures for calculation of the prospective short-circuitcurrents with an unbalanced short circuit in high-voltage three-phase a.c. systems operatingat nominal frequency 50 Hz or...