IEC_TR_61597-2021.pdf

IEC TR 61597 Edition 2.0 2021-06 TECHNICAL REPORT Overhead electrical conductors Calculation methods for stranded bare conductors IEC TR 61597:2021-06(en)THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2021 IEC,Geneva,Switzerland All rights reserved.Unless otherwise specified,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 either IEC or IECs member National Committee in the country of the requester.If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,please contact the address below or your local IEC member National Committee for further information.IEC Central Office Tel.:+41 22 919 02 11 3,rue de Varemb infoiec.ch CH-1211 Geneva 20 www.iec.ch Switzerland About the IEC The International Electrotechnical Commission(IEC)is the leading global organization that prepares and publishes International Standards for all electrical,electronic and related technologies.About IEC publications The technical content of IEC publications is kept under constant review by the IEC.Please make sure that you have the latest edition,a corrigendum or an amendment might have been published.IEC publications search-webstore.iec.ch/advsearchform The advanced search enables to find IEC publications by a variety of criteria(reference number,text,technical committee,).It also gives information on projects,replaced and withdrawn publications.IEC Just Published-webstore.iec.ch/justpublished Stay up to date on all new IEC publications.Just Published details all new publications released.Available online and once a month by email.IEC Customer Service Centre-webstore.iec.ch/csc If you wish to give us your feedback on this publication or need further assistance,please contact the Customer Service Centre:salesiec.ch.IEC online collection-oc.iec.ch Discover our powerful search engine and read freely all the publications previews.With a subscription you will always have access to up to date content tailored to your needs.Electropedia-www.electropedia.org The worlds leading online dictionary on electrotechnology,containing more than 22 000 terminological entries in English and French,with equivalent terms in 18 additional languages.Also known as the International Electrotechnical Vocabulary(IEV)online.IEC TR 61597 Edition 2.0 2021-06 TECHNICAL REPORT Overhead electrical conductors Calculation methods for stranded bare conductors INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 29.240.20 ISBN 978-2-8322-9938-8 Registered trademark of the International Electrotechnical Commission Warning!Make sure that you obtained this publication from an authorized distributor.2 IEC TR 61597:2021 IEC 2021 CONTENTS FOREWORD.4 1 Scope.6 2 Normative references.6 3 Terms and definitions.6 4 Symbols,units and abbreviated terms.7 4.1 Symbols and units.7 4.2 Abbreviated terms.8 5 Current carrying capacity.8 5.1 General.8 5.2 Heat balance equation.8 5.3 Calculation method.9 5.4 Joule effect.9 5.5 Solar heat gain.9 5.6 Radiated heat loss.9 5.7 Convection heat loss.10 5.8 Method to calculate current carrying capacity(CCC).10 5.9 Determination of the maximum permissible aluminium temperature.10 5.10 Calculated values of current carrying capacity.11 6 Alternating current resistance,Inductive and capacitive reactances.11 6.1 General.11 6.2 Alternating current(AC)resistance.11 6.3 Inductive reactance.12 6.4 Capacitive reactance.14 7 Elongation of stranded conductors.14 7.1 General.14 7.2 Thermal elongation.15 7.3 Stress-strain properties.18 7.4 Assessment of final elastic modulus.20 8 Conductor creep.22 8.1 General.22 8.2 Creep of single wires.23 8.3 Total conductor creep.24 8.4 Prediction of conductor creep.24 8.5 Creep values.24 9 Loss of strength.25 Annex A(informative)A practical example of CCC calculation.27 A.1 Basic Assumptions.27 A.2 CCC calculation.27 Annex B(informative)Indicative conditions for CCC calculation.29 Bibliography.30 Figure 1 Typical creep curve.23 Figure 2 Loss of strength of aluminium A1 as a function of temperature.26 Figure 3 Loss of strength of aluminium A2.26 IEC TR 61597:2021 IEC 2021 3 Table 1 Values of Kg for inductive reactance calculations.13 Table 2 Coefficient of linear expansion of inhomogeneous conductors designated Ax/Sxy.17 Table 3 Coefficient of linear expansion of inhomogeneous conductors designated Ax/20SA.18 Table 4 Typical stress-strain data of stranded conductors based on published test results.21 Table 5 Final modulus of elasticity calculated with Ea=55000 MPa and Es=190000 MPa.22 Table 6 Final modulus of elasticity calculated with Ea=55000 MPa and Es=159000 MPa(20SA).22 Table 7 Indicative creep values of stranded conductors(25%RTS,20).25 Table B.1 Indicative conditions for CCC calculation.29 4 IEC TR 61597:2021 IEC 2021 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ OVERHEAD ELECTRICAL CONDUCTORS CALCULATION METHODS FOR STRANDED BARE C