May,31

IEC 60375-2003 pdf – Conventions concerning electric and magnetic circuits.

1 Scope This International Standard lays down rules for signs and reference directions and reference polarities for electric currents and voltages in electric networks, as well as for the corresponding quantities in magnetic circuits. In Clauses 3 to 9, the time dependence is arbitrary. Clause 10 details the rules and recom- mendations for complex notation. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050-121:1998, International Electrotechnical Vocabulary (IEV) – Part 121: Electro- magnetism IEC 60050-131:2002, International Electrotechnical Vocabulary (IEV) – Part 131: Circuit theory IEC 60617, Graphical symbols for diagrams 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 terminal point of interconnection of an electric circuit element, an electric circuit or a network (IEC 60050-131:2002, 131-13-03) with other electric circuit elements, electric circuits or networks [IEV-131-11-11] NOTE 1 For an electric circuit element, the terminals are the points at which or between which the related integral quantities are defined. At each terminal, there is only one electric current from outside into the element. NOTE 2 The term “terminal” has a related meaning in IEC 60050-151. 3.2 circuit element in electromagnetism, mathematical model of a device characterized by one or more relations between integral quantities [IEV-131-11-03]

3.3 two-terminal element electric circuit element having two terminals [IEV 131-11-16] 3.4 n -terminal circuit element electric circuit element having n terminals with generally n > 2 [IEV-131-11-13] NOTE For an n-terminal electric circuit element: 1) the algebraic sum of the electric currents into the element through the terminals is zero at any instant; 2) there are n – 1 independent relations between integral quantities. 3.5 network in network topology, set of ideal circuit elements and their interconnections, considered as a whole [IEV-131-13-03] NOTE 1 The term “electric network” is defined in IEC 60050-131-11-07 and in IEC 60050-151. NOTE 2 In diagrams in this standard, a box, IEC 60617 symbol, represents any network, unless otherwise specified. 3.6 branch subset of a network, considered as a two-terminal circuit, consisting of a circuit element or a combination of circuit elements [IEV-131-13-06] 3.7 node, vertex (US) end-point of a branch connected or not to one or more other branches [IEV-131-13-07] 3.8 loop closed path passing only once through any node [IEV-131-13-12] 3.9 tree connected set of branches joining all the nodes of a network without forming a loop [IEV-131-13-13] 3.10 co-tree set of the branches of a network not included in a chosen tree [IEV-131-13-14]

3.11 maillon branche d’un co-arbre [VEI 131-13-15] 3.12 maille ensemble des branches constituant une boucle et ne contenant qu’un seul maillon d’un co- arbre donné [VEI 131-13-16] Remarque: En français, les termes tension et différence de potentiel ont le même sens dans le domaine des circuits électriques. Dans la version en langue anglaise du VEI, voltage est le terme privilégié et electric tension, souvent abrégé en tension, est un terme toléré. La présente norme emploie en anglais le terme voltage. Le terme courant électrique est souvent abrégé en courant, conformément à la CEI 60050-121. Pour les réseaux électriques à éléments localisés (voir la CEI 60050-131), la loi de Kirchhoff des courants ou loi de Kirchhoff des noeuds (voir 4.4) s’applique à la grandeur courant et la loi de Kirchhoff des tensions ou loi de Kirchhoff des mailles (voir 5.4) s’applique à la grandeur tension.

5 Polarity rules for voltage 5.1 Voltage In an electric network, a voltage between two ordered nodes, a and b, is the difference of the electric potentials at node a and node b. 5.2 Reference polarity for a pair of nodes The polarity of a pair of nodes is determined by the ordering of the nodes. The reference polarity may be chosen arbitrarily. For two nodes, a and b, with the ordering ab, the voltage u ab is defined as u V V ab a b = = − − , where V a and V b are the electric potentials at the nodes a and b, respectively. 5.3 Indication of the reference polarity First method: The reference polarity for a voltage is indicated by a line, straight or curved, with a plus sign (+) at the node that comes first in the ordering of the nodes (a in ab). If wanted, a minus sign may be attached to the other end of the line. The letter symbol representing the voltage is placed close to the line (see Figure 5).

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