IEC 60375 pdf download – Conventions concerning electric and magnetic circuits

IEC 60375 pdf download – Conventions concerning electric and magnetic circuits
1 scope
This International Standard lays down rules for signs and reference directions and referencepolarities for electric currents and voltages in electric networks， as well as for thecorresponding 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.
2Normative 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 editionof 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 theoryIEC 60617,Graphical symbols for diagrams
3Terms 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 ornetworks
[IEV-131-11-11]
NOTE1 For an electric circuit element, the terminals are the points at which or between which the related integralquantities 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 lEC 60050-151.
3.2
circuit element
in electromagnetism， mathematical model of a device characterized by one or more relationsbetween integral quantities
[IEV-131-11-03]
3.3
bipole elementaire
element de circuit electrique a deux bornes[VEI131-11-16]
3.4
multipole élementaire
element de circuit electrique a plus de deux bornes[VEI131-11-13]
NOTE Pour un multipble elementaire a bornes:
1) la somme algebrique des courants electriques entrant dans /’element par les bornes est nulle a tout instant;2y il y a n – 1 relations independantes entre les grandeur integralas.
3.5
reseau
en topologie des reseaux,ensemble d’elements de circuits ideaux et de leurs interconnexions,considere comme un tout
[VEI131-13-03]
NOTE 1 Le terme aréseau electriqueo est defini en 131-11-07 et dans la CEl 60050-151.
NOTE 2Dans les schemas de la presente norme, une boite，symbole de la CEI 60617,represente un reseauquelconque, sauf mention contraire.
3.6
branche
sous-ensemble d’un réseau, considere comme un bipble,constitue par un element de circuitou par une combinaison delements de circuit
[VEI131-13-06]
3.7
noeud
sommet (desuet)
extremite d’une branche, connectee ou non a une ou plusieurs autres branches[VEI131-13-07]
3.8
boucle
chemin ferme passant une seule fois par tout nmud[VEI131-13-12]
3.9
arbre
ensemble connexe de branches reliant tous les nauds d’un réseau sans former de boucle[VEI 131-13-13]
3.10
co-arbre
ensemble des branches d’un reseau non incluses dans un arbre choisi[VEI 131-13-14]
3.11link
branch of a co-tree[lEV-131-13-15]
3.12
mesh
set of branches forming a loop and containing only one link of a given co-tree[IEV-131-13-16]
Remark: The English terms voltage，electric potential difference,and electric tension havethe same meaning in the area of electric circuits. In the English language version of the IEvvoltage is the preferred term and electric tension, often shortened to tension, is an alternative.This standard uses the term voltage.The term electric current is often shortened to currentaccording to lEC 60050-121.
For electric networks with lumped circuit elements (see lEC 60050-131), the Kirchhoff law fornodes (see 4.4) applies for the quantity current,and the Kirchhoff law for meshes (see 5.4)applies for the quantity volfage.
4 Direction rules for current
4.1 Physical direction of current
The net flow of electric charge through a surface is referred to as electric current.Byconvention,the physical direction of the current i is defined as the direction corresponding tothe movement of positive charge. lf the quasi-infinitesimal charge dq passes through apredetermined surface, for example the cross-section of a conductor,during the duration dr,the electric current is
主=dr
d qdt
4.2Reference direction of current
The reference direction for the current in a branch or in a mesh is a direction fixed arbitrarilyalong the branch or around the mesh.A current is considered as positive when its physicaldirection corresponds to the reference direction.
4.3Indication of the reference direction for currents
4.3.1 Indication of the reference direction for currents for a branch
An arrow having the direction corresponding to the reference direction for a current is placed onor near the line representing the branch element, or near the branch element. (See Figure 1.)The notations in Figures 1a and 1b are preferred.