Shortcircuit currents

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Collection Technique ..........................................................................

Cahier technique no. 158
Calculation of short-circuit currents

B. de Metz-Noblat F. Dumas C. Poulain

Building a New Electric World

"Cahiers Techniques" is a collection of documents intended for engineers and technicians, people in the industry who are looking for more in-depth informationin order to complement that given in product catalogues. Furthermore, these "Cahiers Techniques" are often considered as helpful "tools" for training courses. They provide knowledge on new technical and technological developments in the electrotechnical field and electronics. They also provide better understanding of various phenomena observed in electrical installations, systems and equipment.Each "Cahier Technique" provides an in-depth study of a precise subject in the fields of electrical networks, protection devices, monitoring and control and industrial automation systems. The latest publications can be downloaded from the Schneider Electric internet web site. Code: See section Section: Press Please contact your Schneider Electric representative ifyou want either a "Cahier Technique" or the list of available titles. The "Cahiers Techniques" collection is part of the Schneider Electric’s "Collection technique".

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no. 158
Calculation of short-circuit currents

Benoît de METZ-NOBLAT Graduate Engineer from ESE (Ecole Supérieure d’Electricité), he worked first for Saint-Gobain,then joined Schneider Electric in 1986. He is now a member of the Electrical Networks competency group that studies electrical phenomena affecting power system operation and their interaction with equipment.

Frédéric DUMAS After completing a PhD in engineering at UTC (Université de Technologie de Compiègne), he joined Schneider Electric in 1993, initially developing software for electricalnetwork calculations in the Research and Development Department. Starting in 1998, he led a research team in the field of industrial and distribution networks. Since 2003, as a project manager, he has been in charge of the technical development of electrical distribution services.

Christophe POULAIN Graduate of the ENI engineering school in Brest, he subsequented followed the special engineeringprogramme at the ENSEEIHT institute in Toulouse and completed a PhD at the Université Pierre et Marie Curie in Paris. He joined Schneider Electric in 1992 as a research engineer and has worked since 2003 in the Electrical Networks competency group of the Projects and Engineering Center.

ECT 158 updated September 2005


Abbreviations BC MLVS Symbols A Breaking capacity. Main low voltageswitchboard. Cross-sectional area of conductors. Angle between the initiation of the fault and zero voltage. Voltage factor. Power factor (in the absence of harmonics). Instantaneous electromotive force. Electromotive force (rms value). Phase angle (current with respect to voltage). Instantaneous current. Alternating sinusoidal component of the instantaneous current. Aperiodic component of theinstantaneous current. Maximum current (first peak of the fault current). Current (rms value). Short-circuit breaking current (IEC 60909). Steady-state short-circuit current (IEC 60909). Initial symmetrical short-circuit current (IEC 60909). Rated current of a generator. Design current. Steady-state short-circuit current (Isc3 = three-phase, Isc2 = phase-to-phase, etc.). Factor depending on the...