IEC 60068-2-14(2009)

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IEC 60068 provides a test to detemine the ability of components,equipment or other articles to withstand rapid changes of ambient temperature.
EC Ec60068-2-14 Edition 6.0 2009-01 NTERNATIONAL STANDARD NORME INTERNATIONALE BASIC SAFETY PUBLICATION PUBLICATION FONDAMENTALE DE SECURITE Environmental testing Part 2-14: Tests- Test N: Change of temperature Essais d'environnement Partie 2-14: Essais-Essai N: Variation de temperature INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE PRICE CODE CODE PRIX R cs19040 SBN28318-10227 3 Registered trademark of the Intemational Electrotechnical Commission Frond d b s under ts w Ec omma m te la Commission Electrotechnique Intematiomle 标准分享网www.bzfxw.com兔费下 2 60068-2-14:|EC:2009 CONTENTS FOREWORD.…4 INTRODUCTION 2 Normative references 777 3 Field conditions of changing temperature 4 General .8 4.1 Design of change of temperature tests ....... 4.2 Test parameters,.,.,,.,.,.,..,.,.,, 3 Purpose and choice of the tests.......... 4.4 Choice of the duration of the exposure....,…,……8 4.5 Choice of the duration of the transfer time 9 4.6 Applicability limits of change of temperature tests..... 5 Guid ance for the selection of the kind of test 10 6 Initial and final measurements 10 6.1 Initial measurements 10 6.2 Final measurements 10 7 Test Na: Rapid change of temperature with prescribed time of transfer.........10 7.1 General description of the test..........................10 72 Testing procedure…… 10 7.2.1 Testing chamber................ 10 7. 2.2 Mounting or supporting of the test specimen...............11 7.2.3 Severities 7.2.4 Conditioning 411 7.2.5 Test cycle,,,..,.,.11 7.3 Recovery. …12 7.4 Information to be given in the relevant specification 12 8 Test Nb: Change of temperature with specified rate of change... 13 8.1 General description of the test 8.2 Testing procedure... 8.2.1 Testing chamber .13 8.22 Mounting or supporting of the test specimen.…,…………13 8.2.3 Severities 13 8.2.4 Conditioning....... 8.2.5 Test cycle 14 8.3 Recovery..,....,…,,….15 8. 4 Information to be given in the relevant specification...........15 9 Test Nc: Rapid change of temperature, two-fluid-bath method 16 9.1 General description of the test. ................................,.............................................16 9.2 Testing procedure............. 9.2.1 Testing equipment...,.,.,.,.,.,.,.,.,,… 9.2.2 Severities 9.2.3 Conditioning…...,.,.,....,.,,.16 9.3 Test cycle 9.4 Recovery.. ,,.4,,,,,来 ,,,,.,,斗4, 17 9.5 Information to be given in the relevant specification .............................................17 hintere nba Com Crowded by HS undar Rente wth EC No reproduction or networking permd wutou loanee from IHB 60068-2-14::|EC:2009 3 10 Information to be given in the test report Figure 1 Determination of test duration time(t,1)..... Figure2- Na test cycle,……,…,…,……,…,,.12 Figure 3-Nb test cycle.,...... Figure 4-Nc test cycle 17 以匙mh 标准分享网www.bzfxw.com免费下 60068-2-14:EC:2009 INTERNATIONAL ELECTROTECHNICAL COMMISSION ENVIRONMENTAL TESTING Part 2-14: Tests-Test N: Change of temperature FOREWORD 1) The International Electrotechnical Commission(IEC)is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEc is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEc publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as " IEC Publication(s)"). Their preparation is entrusted to technical committees, any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non- governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization( Iso)in accordance wi th conditions determined by agreement between the two organizations 2)The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested lEC Natio nal Com mittees 3)IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. while all reasonable efforts are made to ensure that the technical content of iec Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user 4)In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter 5)IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication 6)All users should ensure that they have the latest edition of this publication 7) No liability shall attach to lEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any person al injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs(including legal fees)and expenses arising out of the publication, 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 indis pensable for the correct application of this publication 9) Attention is drawn to the poss ibility that some of the elements of this lEc 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 60068-2-14 has been prepared by lEC technical committee 104: Environmental conditions, classification and methods of test. This sixth edition cancels and replaces the fifth ed ition, published in 1984, and its amendment (1986)and constitutes a technical revision The major changes with regard to the previous edition concern merging of the previous version of lEC 60068-2-14 with IEC 60068-2-33: Guidance on change of temperature tests updating of the figures, changes to some of the wording and editorial corrections made for clarification 匙am ucon or networking permed wtthout loanee from IHS 60068-2-14::|EC:2009 5 The text of this standard is based on the following documents: FDIS Report on voting 104/481/FD|s 104/486/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the iSo/EC Directives, Part 2. It has the status of a basic safety publication in accordance with IEC Guide 104 A list of all the parts in the IEC 60068 series, under the general title Environmental testing, can be found on the iec we bsite The committee has decided that the contents of this publication will remain unchanged until themaintenanceresultdateindicatedontheiecwebsiteunder"http:llwebstoreiecch"in the data related to the specific publication. At this date, the publication will be reconfirmed withdrawn replaced by a revised edition, or amended Frond b s under nte wh Ec omma 标准分享网www.bzfxw.com免费下 6 60068-2-14:|EC:2009 INTRODUCTION A change of temperature test is intended to determine the effect on the specimen of a change of temperature or a succession of changes of temperature It is not intended to show effects which are due only to high or low temperatures. For these effects, the dry heat test or the cold test should be used. The effect of such tests is determined by values of high and low conditioning temperature between which the change is to be effected the conditioning times for which the test specimen is kept at these temperatures, the rate of change between these temperatures the number of cycles of conditioning the amount of heat transfer into or from the specimen Guidance on the choice of suitable test parameters for inclusion in the detail specification is given throughout this standard 匙am ucon or networking permed wtthout loanee from IHS 60068-2-14::|EC:2009 7 ENVIRONMENTAL TESTING Part 2-14: Tests- Test N: change of temperature Scope This part of IEC 60068 provides a test to determine the ability of components, equipment or i other articles to withstand rapid changes of ambient temperature. The exposure times adequate to accomplish this will depend upon the nature of the specimen : :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 60068(all parts), Environmental testing EC 60068-2-1, Environmental testing-Part 2-1: Tests- Test A: Cold lEC 60068-2-2, Environmental testing- Part 2-2: Tests- Test B: Dry heat lEC 60068-2-17, Environmental testing-Part 2-17: Tests- Test Q: Sealing lEC Guide 104, The preparation of safety publications and the use of basic safety publications and group safety publications 3 Field conditions of changing temperature It is common in electronic equipment and components that changes of temperature occur Parts inside equipment undergo slower changes of temperature than those on an externa surface when the equipment is not switched on Rapid changes of temperature may be expected when equipment is transported from warm indoor environments into cold open air conditions or vice versa, when equipment is suddenly cooled by rainfall or immersion in cold water, in externally mounted airborne equipment, under certain conditions of transportation and storage Components will undergo stresses due to changing temperature when high temperature gradients build up in an equipment after being switched on, e.g. in the neighbourhood of high wattage resistors, radiation can cause rise of surface temperature in neighbouring components while other portions are still cool. Artificially cooled components may be subjected to rapid temperature changes when the cooling system is switched on. Rapid changes of temperature in components may also be induced during manufacturing processes of equipment. Both the number and amplitude of temperature changes and the time interval between them are important 以匙mh 标准分享网www.bzfxw.com兔费下 8 60068-2-14:|EC:2009 4 General 4.1 Design of change of temperature tests Tests Na, Nb and Nc comprise alternate periods at a high and at a low temperature with well defined transfers from one temperature to the other. The conditioning run from laboratory ambient to the first conditioning temperature then to the second conditioning temperature then back to laboratory ambient is considered one test cycle 4.2 Test parameters Test parameters comprise the following laboratory ambient high temperature low temperature duration of exposure; transfer time or rate of change number of test cycles The high and low temperatures are understood to be ambient temperatures which will be reached by most specimens with a certain time-lag Only in exceptional cases may they be specified outside the normal storage or operating temperature range of the object under test The test is accelerated because the number of severe changes of temperature in a given period is greater than that which will occur under field conditions 4.3 Purpose and choice of the tests Change of temperature testing is recommended in the following cases evaluation of electrical performance during a change of temperature, Test Nb; evaluation of mechanical performance during a change of temperature, Test Nb evaluation of electrical performance after a specified number of rapid changes of temperature, Test Na or Test Nc evaluation of the suitability of mechanical components, and of materials and com binations of materials to withstand rapid changes of temperature, Test Na or Test No evaluation of the suitability of construction of components to withstand artificial stressing Test Na or Test Nc i The change of temperature tests specified in the lEc 60068 series is not intended to evaluate the difference in material constants or electrical performance when operating under temperature stability at the two extremes of temperature 4.4 Choice of the duration of the exposure The duration of the exposure should be based on the requirements stated in 7.2.3, 8.2.3 or 9.2.2, or as stated in the relevant specification, keeping in mind the following points: a)The exposure begins as soon as the specimen is in the new environment b) Stabilization occurs when the temperature difference (an) between the specimen and the test medium is within 3 K to 5 K, or as stated in the test specification the stabilization period,(ts), is from the start of exposure until the time when the temperature is within the 匙am ucon or networking permed wtthout loanee from IHS

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