Lecture

Calculation of Short-Circuit Currents

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In course

EE-370: Electric power systems

Ce cours décrit les composants d'un réseau électrique. Il explique le fonctionnement des réseaux électriques et leurs limites d'utilisation. Il introduit les outils de base permettant de les piloter. ...

Description

This lecture covers the calculation of short-circuit currents in electrical networks, focusing on symmetrical three-phase systems and isolated two-phase systems. It explains the determination of nodal impedances, equivalent diagrams, and the application of Thévenin's theorem. The instructor discusses the calculation of DC currents at specific nodes, the reduction of networks, and the matrices required for impedance calculations. Various examples are provided to illustrate the concepts, including the calculation of current in different network configurations. The lecture emphasizes the importance of considering only relevant components in the calculations and neglecting nonlinear phenomena.

Instructor

Sidi-Rachid Cherkaoui

Rachid Cherkaoui received the M.S. degree in electrical engineering and the Ph.D. degree from Swiss Federal Institute of Technology (EPFL), Lausanne, in 1983 and 1992 respectively. From 1983 to 1987, he worked at Entreprises Electriques Fribourgeoises (Swiss electrical utility) developing a state estimator and security analysis tools for the HV transmission system of that company. From 1987 to 1992, he joined the power system laboratory of EPFL where he achieved his Ph.D. thesis in the field of optimal operation topologies for distribution systems. In this respect, he was the recipient of the ABB Swiss Award83. Since 1993, he is leading the research activities in the field of optimization and simulation techniques applied to electrical power and distribution systems. Presently his main research topics are electricity market deregulation, distributed generation and storage, and, power system vulnerability mitigation. He is senior member of IEEE, member of technical program committees of various conferences, member of CIGRE task forces C5-2, and IEEE Swiss Chapter officer since 2005. He serves regularly as reviewer for different journals and conferences. Dr. Cherkaoui is the author or co-author of more than 50 scientific publications.

Official source

Ontological neighbourhood

Physics

Electromagnetism: Electrical networks

Related concepts (32)

Network analysis (electrical circuits)

In electrical engineering and electronics, a network is a collection of interconnected components. Network analysis is the process of finding the voltages across, and the currents through, all network components. There are many techniques for calculating these values; however, for the most part, the techniques assume linear components. Except where stated, the methods described in this article are applicable only to linear network analysis.

Direct current

Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A term formerly used for this type of current was galvanic current.

Electrical network

An electrical network is an interconnection of electrical components (e.g., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage sources, current sources, resistances, inductances, capacitances). An electrical circuit is a network consisting of a closed loop, giving a return path for the current. Thus all circuits are networks, but not all networks are circuits (although networks without a closed loop are often imprecisely referred to as "circuits").

Short circuit

A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit. The opposite of a short circuit is an open circuit, which is an infinite resistance (or very high impedance) between two nodes. A short circuit is an abnormal connection between two nodes of an electric circuit intended to be at different voltages.

Prospective short-circuit current

The prospective short-circuit current (PSCC), available fault current, or short-circuit making current is the highest electric current which can exist in a particular electrical system under short-circuit conditions. It is determined by the voltage and impedance of the supply system. It is of the order of a few thousand amperes for a standard domestic mains electrical installation, but may be as low as a few milliamperes in a separated extra-low voltage (SELV) system or as high as hundreds of thousands of amps in large industrial power systems.

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