1、 IEC 60068-3-1 Edition 2.0 2011-08 INTERNATIONAL STANDARD NORME INTERNATIONALE Environmental testing Part 3-1: Supporting documentation and guidance Cold and dry heat tests Essais denvironnement Partie 3-1: Documentation daccompagnement et guide Essais de froid et de chaleur sche IEC 60068-3-1:2011
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16、nts ou contactez-nous: Email: csciec.ch Tl.: +41 22 919 02 11 Fax: +41 22 919 03 00 IEC 60068-3-1 Edition 2.0 2011-08 INTERNATIONAL STANDARD NORME INTERNATIONALE Environmental testing Part 3-1: Supporting documentation and guidance Cold and dry heat tests Essais denvironnement Partie 3-1: Documentat
17、ion daccompagnement et guide Essais de froid et de chaleur sche INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE M ICS 19.040 PRICE CODE CODE PRIX ISBN 978-2-88912-626-2 Registered trademark of the International Electrotechnical Commission Marque dpose de la Commi
18、ssion Electrotechnique Internationale 2 60068-3-1 IEC:2011 CONTENTS FOREWORD . 3 1 Scope . 5 2 Normative references . 5 3 Terms and definitions . 5 4 Selection of test procedures . 5 4.1 General background 5 4.1.1 General . 5 4.1.2 Ambient temperature . 6 4.1.3 Specimen temperatures . 6 4.1.4 Specim
19、ens without heat dissipation . 6 4.1.5 Specimens with heat dissipation 6 4.2 Mechanisms of heat transfer . 6 4.2.1 Convection 6 4.2.2 Radiation . 9 4.2.3 Thermal conduction . 10 4.2.4 Forced air circulation . 10 4.3 Test chambers 10 4.3.1 General . 10 4.3.2 Methods of achieving the required conditio
20、ns in the test chamber 11 4.4 Measurements . 11 4.4.1 Temperature 11 4.4.2 Air velocity 11 Annex A (informative) Effect of airflow on chamber conditions and on surface temperatures of test specimens 12 Figure 1 Experimental data on the effect of airflow on surface temperature of a wire- wound resist
21、or Radial airflow . 7 Figure 2 Experimental data on the effect of airflow on surface temperature of a wire- wound resistor Axial airflow . 8 Figure 3 Temperature distribution on a cylinder with homogeneous heat generation in airflow of velocities 0,5, 1 and 2 ms 19 Table 1 Influence parameters when
22、testing heat-dissipating specimens . 11 60068-3-1 IEC:2011 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ ENVIRONMENTAL TESTING Part 3-1: Supporting documentation and guidance Cold and dry heat tests FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for stand
23、ardization 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 Int
24、ernational 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 participa
25、te 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 with conditions determined by agreement betwee
26、n 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 IEC National Committees. 3) IEC Publications
27、 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
28、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 n
29、ational or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any servic
30、es carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC Natio
31、nal Committees for any personal 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
32、 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 possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall
33、 not be held responsible for identifying any or all such patent rights. International Standard IEC 60068-3-1 has been prepared by IEC technical committee 104: Environmental conditions, classification and methods of test. This second edition cancels and replaces the first edition, published in 1974,
34、and constitutes a technical revision. The main changes with regard to the previous edition are as follows: removal of guidance regarding thermal characteristics of chamber walls; revision of sections that address environmental chambers that do not use movement of air for temperature control. 4 60068
35、-3-1 IEC:2011 The text of this standard is based on the following documents: FDIS Report on voting 104/555/FDIS 104/558/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 accorda
36、nce with the ISO/IEC Directives, Part 2. A list of all parts in the IEC 60068 series, under the general title Environmental testing can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web
37、 site 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. 60068-3-1 IEC:2011 5 ENVIRONMENTAL TESTING Part 3-1: Supporting documentation and guidance Cold and dry heat t
38、ests 1 Scope This part of IEC 60068 provides guidance regarding the performance of cold and dry heat tests. 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,
39、the latest edition of the referenced document (including any amendments) applies. IEC 60068-1, Environmental testing Part 1: General and guidance IEC 60068-2-1, Environmental testing Part 2-1: Tests Test A: Cold IEC 60068-2-2, Environmental testing Part 2-2: Tests Test B: Dry heat 3 Terms and defini
40、tions For the purposes of this document, the following terms and definitions apply. 3.1 heat-dissipating specimen specimen on which the hottest point on its surface, measured in free-air conditions and under the air pressure as specified in IEC 60068-1, is more than 5 K above the ambient temperature
41、 of the surrounding atmosphere after thermal stability has been reached 3.2 non heat-dissipating specimen specimen that does not produce heat to a level that can affect the air temperature surrounding the specimen or those specimens located nearby 3.3 free-air conditions conditions within an infinit
42、e space where the movement of the air is affected only by the heat- dissipating specimen 4 Selection of test procedures 4.1 General background 4.1.1 General Specimen performance may be influenced or limited by the temperatures in which the specimen is operated. The level of influence may be affected
43、 by test gradients that exist within the test system (climatic or environmental chamber) and internal temperatures within 6 60068-3-1 IEC:2011 the specimen itself. In order to determine the level of influence that exists and to ensure that the specimen is designed appropriately, cold and/or dry heat
44、 tests are performed. 4.1.2 Ambient temperature The maximum and minimum values of the ambient temperature where the specimen will be subjected to should be known. Preferred values for testing purposes are provided in IEC 60068-2-1 and/or IEC 60068-2-2. Difficulties can arise due to the fact that hea
45、t transfer causes temperature variations in the area surrounding the specimen. Consequently, the affect from the transfer of heat to the ambient temperature of the surrounding atmosphere should be considered. Air flow related to spacing between specimens should also be considered when performing a t
46、est. 4.1.3 Specimen temperatures The performance of the specimen can be affected by its own temperature in the case of heat- dissipating specimens. Because of this, when controlling the test environment, it may be necessary to measure the temperature of the specimen under test at different locations
47、, both internally and externally. 4.1.4 Specimens without heat dissipation lf the ambient temperature is uniform and constant and there is no generation of heat within the specimen, heat will flow from the ambient atmosphere into the specimen if the ambient atmosphere is at a higher temperature. Con
48、versely, heat will flow from the specimen into the ambient atmosphere if the specimen is at a higher temperature. This heat transfer will continue until the specimen has completely reached thermal equilibrium with the surrounding atmosphere. From that moment on, the heat transfer ceases and will not
49、 start again unless the ambient temperature changes. 4.1.5 Specimens with heat dissipation If heat is generated within the specimen the temperature of the specimen will rise to a stabilization point above the ambient temperature. It follows that if a steady temperature is reached, heat will flow continuously from the specimen by convection, radiation, and/or conduction into the atmosphere whereby t
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