1、 IEC 60724Edition 3.1 2008-11INTERNATIONAL STANDARD NORME INTERNATIONALEShort-circuit temperature limits of electric cables with rated voltages of 1 kV (Um= 1,2 kV) and 3 kV (Um= 3,6 kV) Limites de temprature de court-circuit des cbles lectriques de tensions assignes de 1 kV (Um= 1,2 kV) et 3 kV (Um
2、= 3,6 kV) IEC60724:2000+A1:2008 THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2008 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
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16、isitez le FAQ du Service clients ou contactez-nous: Email: csciec.chTl.: +41 22 919 02 11 Fax: +41 22 919 03 00 IEC 60724Edition 3.1 2008-11INTERNATIONAL STANDARD NORME INTERNATIONALEShort-circuit temperature limits of electric cables with rated voltages of 1 kV (Um= 1,2 kV) and 3 kV (Um= 3,6 kV) Li
17、mites de temprature de court-circuit des cbles lectriques de tensions assignes de 1 kV (Um= 1,2 kV) et 3 kV (Um= 3,6 kV) INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE CBICS 29.060.20 PRICE CODECODE PRIXISBN 2-8318-1014-7 Registered trademark of the Internationa
18、l Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale 2 60724 IEC:2000+A1:2008 CONTENTS FOREWORD.3 INTRODUCTION.5 1 Scope.6 2 Normative references6 3 Factors governing the application of the temperature limits .6 3.1 General .6 3.2 Cables.7 3.3 Accessories.7 3.4
19、 Installation conditions 8 4 Maximum permissible short-circuit temperatures for cables with rated voltages of 1 kV (Um= 1,2 kV) and 3 kV (Um= 3,6 kV) 8 4.1 Insulation materials8 4.2 Oversheath and bedding materials where there are no electrical or other requirements 9 4.3 Conductor/metallic sheath/s
20、creen/armour materials and methods of connection .9 Table 1 Temperature limits for insulation materials .9 Table 2 Temperature limits for oversheath materials.9 Table 3 Temperature limits for current-carrying components.10 60724 IEC:2000+A1:2008 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ SHORT-CI
21、RCUIT TEMPERATURE LIMITS OF ELECTRIC CABLES WITH RATED VOLTAGES OF 1 kV (Um= 1,2 kV) AND 3 kV (Um= 3,6 kV) FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). Th
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30、ion, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibilit
31、y that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 60724 has been prepared by IEC technical committee 20: Electric cables. This consolidated version of IE
32、C 60724 consists of the third edition (2000) documents 20/399/FDIS and 20/418/RVD and its amendment 1 (2008) documents 20/951/FDIS and 20/974/RVD. The technical content is therefore identical to the base edition and its amendment and has been prepared for user convenience. It bears the edition numbe
33、r 3.1. A vertical line in the margin shows where the base publication has been modified by amendment 1. 4 60724 IEC:2000+A1:2008 The committee has decided that the contents of the base publication and its amendments will remain unchanged until the maintenance result date indicated on the IEC web sit
34、e under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed, withdrawn, replaced by a revised edition, or amended. 60724 IEC:2000+A1:2008 5 INTRODUCTION Editorially, this third edition of IEC 60724 is brought into line with IEC 6
35、0986, second edition, and IEC 61443, first edition. The following four aspects may be applicable when selecting the short-circuit rating of a cable system: a) the permissible maximum temperature limits for cable components (e.g. conductor, insulation, screen or metallic sheath, bedding, armour and o
36、versheath). For practical purposes, the energy producing the temperature rise is usually expressed by an equivalent (I2t) value so that the permitted maximum duration for a given short-circuit current can be calculated; b) the maximum value of current which will not cause mechanical failure (such as
37、 bursting) due to electromagnetic forces. Irrespective of any temperature limitations, this determines a maximum current which should not be exceeded; c) the thermal performance of joints and terminations at the limits of current and duration specified for the associated cable. Accessories should al
38、so withstand the thermo-mechanical and electromagnetic forces produced by the short-circuit current in the cable; d) the influence of installation conditions on the above three aspects. Aspect a) is dealt with in detail, and the limits given are based on a consideration of the cable only. A single s
39、hort-circuit application is not expected to produce any significant damage to the cable, but repeated short-circuits may cause cumulative damage. Guidance is given, where appropriate, on aspects c) and d) mainly as they concern thermo-mechanical forces in the conductors and metallic sheath. Aspect b
40、) is not covered in this standard. The limits recommended in this International Standard should be used for guidance only. It is not possible to provide complete limits for joints and terminations because their construction is not standardized and performance varies. Where the full short-circuit cap
41、ability of the cable is needed, the accessories should be designed appropriately, but this is not always economically justified and the short-circuit capability of a cable system may be determined by the performance of its joints and terminations. Where possible, guidance has been included on the pe
42、rformance of accessories when they are installed on cables subject to the short-circuit limits given in this standard. 6 60724 IEC:2000+A1:2008 SHORT-CIRCUIT TEMPERATURE LIMITS OF ELECTRIC CABLES WITH RATED VOLTAGES OF 1 kV (Um= 1,2 kV) AND 3 kV (Um= 3,6 kV) 1 Scope This International Standard gives
43、 guidance on the short-circuit maximum temperature limits of electric cables having rated voltages of 1 kV (Um = 1,2 kV) and 3 kV (Um = 3,6 kV), with regard to the following: insulating materials; oversheath and bedding materials; conductor and metallic sheath materials and methods of connection. Th
44、e design of accessories and the influence of the installation conditions on the temperature limits are taken into consideration. The calculation of the permissible short-circuit current in the current-carrying components of the cable should be carried out in accordance with IEC 60949. 2 Normative re
45、ferences 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 60055 (all parts), Paper-insulated m
46、etal-sheathed cables for rated voltages up to 18/30 kV (with copper or aluminium conductors and excluding gas-pressure and oil-filled cables) IEC 60502-1:1998, Power cables with extruded insulation and their accessories for rated voltages from 1 kV (Um= 1,2 kV) up to 30 kV (Um= 36 kV) Part 1: Cables
47、 for rated voltages of 1 kV (Um= 1,2 kV) and 3 kV (Um= 3,6 kV) IEC 60949:1988, Calculation of thermally permissible short-circuit current, taking into account the non-adiabatic heating effects 3 Factors governing the application of the temperature limits 3.1 General The short-circuit temperatures gi
48、ven in clause 4 are the actual temperatures of the current-carrying component as limited by the adjacent material in the cable and are valid for short-circuit durations of up to 5 s. When calculating the allowable short-circuit current, these temperatures will be obtained if heat loss into the insul
49、ation during the short-circuit is taken into account (non-adiabatic heating). If heat loss during the short-circuit is neglected (adiabatic heating), the calculations give short-circuit currents that are on the safe side. NOTE The temperature limits given in clause 4 should also not be exceeded with repeated short-circuits occurring in a short time. 60724 IEC:2000+A1:2008 7 The 5 s time period mentioned is the limit for t
