scope:

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 support for the modelling of electrical equipment in the positive-sequence, the negative-sequence and the zero-sequence system (clause 2), the practical execution of calculations in a low-voltage system (clause 3), a medium- voltage system with asynchronous motors (clause 4) and a power-station unit with its auxiliary network feeding a large number of medium-voltage asynchronous motors and low-voltage motor groups (clause 5). The three examples given in clauses 3, 4 and 5 are similar to those given in IEC 60909-4:2000 but they are revised in accordance with IEC 60909-0, which replaces it. The example, given in chapter 6, is new and mirrors the introduction of the new chapters 6.7 to 6.9 of IEC 60909-0. Clause 7 of this technical report gives the circuit diagram and the data of a test network and the results for a calculation carried out in accordance with IEC 60909-0, to offer the possibility for a comparison between the results found with a digital program for the calculation of short-circuit currents and the given results for I ", i , I , I , I " and i in a high-voltage network with power- k p b k k1 p1 station units, generators, asynchronous motors and lines in four different voltage levels 380 kV, 110 kV, 30 kV and 10 kV.