SHORT-CIRCUIT CURRENT CALCULATION - A COMPARISON BETWEEN METHODS OF IEC AND ANSI STANDARDS USING DYNAMIC SIMULATION AS REFERENCE

An essential issue concerning short-circuit studies is about how much precise should short-circuit calculations be. Simplified procedures ha ve been proposed since many years by International Committees to provi de reference methods for the manual computation and for the use of rat ed, rather than operating, equipment data. Recently, dynamic programs have been used to accurately simulate short-circuit currents. Two wide ly adopted international standards (ANSI/IEEE C37.010.1979 and IEC 909 Standards) are investigated in this paper for comparing and pointing out the most significant differences in methodologies, assumptions, co mputed currents, and results. An outline of the two standards is prese nted and a detailed comparison is carried on. The procedures of the tw o standards are applied to a test network proposed in the IEC 909 Stan dard. Results of calculations by the two standards are compared using the results of a transient study performed by the EMTP simulation prog ram as a reference basis.