iec60865-1

INTERNATIONAL STANDARD

IEC 60865-1

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Second edition 1993-09

Short-circuit currents – Calculation of effects – Part 1: Definitions and calculation methods

This English-language version is derived from the original bilingual publication by leaving out all French-language pages. Missing page numbers correspond to the Frenchlanguage pages.

Reference number IEC 60865-1:1993(E)

Publication numbering As from 1 January 1997 all IEC publications are issued with a designation in the 60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.

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INTERNATIONAL STANDARD

IEC 60865-1


Second edition 1993-09

Short-circuit currents – Calculation of effects – Part 1: Definitions and calculation methods

 IEC 1993 Copyright - all rights reserved No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: [email protected] Web: www.iec.ch

Com mission Electrotechnique Internationale International Electrotechnical Com m ission Международная Электротехническая Комиссия

PRICE CODE

XA

For price, see current catalogue

Publication 865-1 de la

IEC Publication 865-1

CEI

(Second edition 1993)

(Deuxième édition 1993)

de court-circuit Calcul des effets

Short-circuit currents Calculation of effects

Courants

Part 1: Definitions and calculation methods

Partie 1: Définitions et méthodes de calcul


CORRIGENDUM1

Page 64, tableau 2

Page 65, table 2

Dans la troisième colonne, pour un courtcircuit biphasé, au lieu de:

In the third column, for a line-to-line short circuit, instead of:

1,8

1,8

lire:

read:

- (un tiret)

- (dash)

Page 74, figure 2

Page 75, figure 2

Sur la gauche des dessins, ajouter:

Add, at the left-hand side of the drawings:

a) et b) respectivement.

a) and b) respectively.

Page 104, annexe A, article A.2

Page 105, annex A, clause A.2

Remplacer la dernière ligne de l’équation existante par la nouvelle ligne suivante:

Replace the last line of the existing equation by the following new line:

2

Mars 1995

&

arctan

(a/d) + 1 b/d

- 2 arctan

a/d b/d

+ arctan

(a/d) -1

b/d

Oa/d

•

⎠ ⎭

6

⎞

b/d

March 1995


865-1 ©IEC:1993

–3–

CONTENTS Page

FOREWORD

7 Section 1: General


Clause

1.1 Scope and object 1.2 Normative references 1.3 Equations, symbols and units Symbols for section 2 – Electromagnetic effects 1.3.1 Symbols for section 3 – Thermal effects 1.3.2 1.4 Definitions Definitions for section 2 – Electromagnetic effects 1.4.1 1.4.1.1 Main conductor 1.4.1.2 Sub-conductor 1.4.1.3 Fixed support 1.4.1.4 Simple support 1.4.1.5 Connecting piece 1.4.1.6 Short-circuit tensile force, F t 1.4.1.7 Drop force, Ff 1.4.1.8 Pinch force, Fpi 1.4.1.9 Duration of the first short-circuit current flow, Tkl Definitions for section 3 - Thermal effects 1.4.2 1.4.2.1 Thermal equivalent short-time current, 'th 1.4.2.2 Rated short-time withstand current, Ithr 1.4.2.3 Thermal equivalent short-time current density, S th 1.4.2.4 Rated short-time withstand current density, S titt, for conductors 1.4.2.5 Duration of short-circuit current, Tk 1.4.2.6 Rated short time, Tkr

9 9 11 11 17 19 19 19 19 19 19 19 19 19 21 21 21 21 21 21 21 21 21

Section 2: The electromagnetic effect on rigid conductors

and flexible conductors 2.1 General Influence on stress reduction 2.1.1 Consideration of automatic reclosing 2.1.2 2.2 Rigid conductor arrangements Calculation of electromagnetic forces 2.2.1 2.2.1.1 Calculation of peak force between the main conductors during a three-phase short circuit 2.2.1.2 Calculation of peak force between the main conductors during a line-to-line short circuit 2.2.1.3 Calculation of peak value of forces between coplanar sub-conductors 2.2.1.4 Effective distance between main conductors and between sub-conductors

23 23 23 25 25 25 25 25 27

865-1 © IEC:1993

–5– Page

Clause


27 2.2.2 Calculation of stresses in rigid conductors and forces on supports 2.2.2.1 General 27 27 2.2.2.2 Calculation of stresses in rigid conductors 2.2.2.3 Section modulus and factor q of main conductors composed of sub-conductors 31 2.2.2.4 Permitted conductor stress 2.2.2.5 Calculation of forces on supports of rigid conductors 2.2.2.6 Calculation with special regard to conductor oscillation 2.3 Flexible conductor arrangements 2.3.1 General 2.3.2 Effects on main conductors 2.3.2.1 Characteristic dimensions and parameters 2.3.2.2 Tensile force Ft during short circuit caused by swing out (short-circuit tensile force) 2.3.2.3 Tensile force Ff after short circuit caused by drop (drop force) 2.3.2.4 Horizontal span displacement b h and minimum air clearance amjn 2.3.3 Tensile force Fri caused by the pinch effect 2.3.3.1 Characteristic dimensions and parameters 2.3.3.2 Tensile force F in the case of clashing sub-conductors 2.3.3.3 Tensile force Fri in the case of non-clashing sub-conductors 2.4 Structure loads due to electromagnetic effects Design load for post isulators, their suppo rts and connectors 2.4.1 2.4.2 Design load for structures, insulators and connectors, with tensile forces transmitted by insulator chains Design load for foundations 2.4.3

31 33 33 37 37 37 39 43 43 45 47 47 49 51 53 53 55 55

Section 3: The thermal effect on bare conductors and electrical equipment 3.1 General 3.2 Calculation of temperature rise 3.2.1 General Calculation of thermal equivalent short-time current 3.2.2 Calculation of temperature rise and rated short-time withstand current density 3.2.3 for conductors Calculation of the thermal short-circuit strength for different durations 3.2.4 of the short-circuit current 3.2.4.1 Electrical equipment 3.2.4.2 Conductors

57 57 57 57 59 61 61 61

63

FIGURES

73

TABLES

ANNEXES A Equations for calculation of diagrams

105

B Iteration-procedure for calculation of factor rl for the tensile force Fpl in the case of non-clashing bundled conductors according to IEC 865, 2.3.3.3 equation (62)

115

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IEC 60865-1 Ed. 2.0 Short-circuit currents Calculation of effects - Part 1: Definitions and calculation methods

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