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环境试验.指南.低温和干热试验  
 【英文标准名称】  Environmental testing - Guidance - Cold and dry heat tests - Cold and dry heat tests
 【原文标准名称】  环境试验.指南.低温和干热试验
 【标准号】  BS EN 60068-3-1-1999
 【标准状态】  ST
 【国别】  英国
 【发布日期】  1999-09-15
 【实施或试行日期】  1999-09-15
 【发布单位】  英国标准学会(GB-BSI)
 【起草单位】  BSI
 【标准类型】  ()
 【标准水平】  ()
 【中文主题词】  环境试验;辐射;气候试验;温度变化;适宜性;电子设备及元件;产品;热学;试验大气环境;污染控制;电子工程;公差(测量);应力;热传递;辐射热传递;温度;温度测量仪表;试验;电气工程;材料;材料试验;测量;表面;干热试验;方块图;气候;环境;对流;电工产品;热传导;温度分布;低温试验;热循环试验;导热性;指导手册;体积;样品;电学;定义;试验室;试验装置
 【英文主题词】  Block diagrams;Changes of temperature;Climate;Climatic tests;Coldness;Convection;Definition;Definitions;Dry-heat tests;Electrical engineering;Electricity;Electronic engineering;Electronic equipment and components;Electrotechnical products;Emission;Environment;Environmental testing;Guide books;Heat;Heat conduction;Heat transfer;Materials;Materials testing;Measurement;Pollution control;Products;Radiation;Radiative heat transfer;Specimens;Stress;Suitability;Surfaces;Temperature;Temperature distribution;Temperature-measuring instruments;Test atmospheres;Test chamber;Testing;Testing devices;Thermal conductivity;Thermal-cycling tests;Tolerances (measurement);Volume
 【摘要】  Environmental testing —Part 3: Background information —Section 1: Cold and dry heat tests 1. Introduction 1.1 Reference ambient conditions 1.2 Devices without heat-dissipation 1.3 Devices with heat-dissipation 1.4 Ambient temperature 1.5 Surface temperatures 2. Reasons for the differing test procedures 2.1 Mechanisms of heat transfer 3. Test chambers 3.1 General 3.2 Methods of achieving the required conditions in the test chamber 4. Measurements 4.1 Temperature 4.2 Air velocity 4.3 Emissivity coefficient Appendix A —Effects of size of chamber on surface temperature of a specimen when no forced air circulation is used FIGURE 1 Heat dissipation per unit surface area of the test specimen at which the deviation between the surface temperature of the specimen in a very large chamber and in a smaller chamber reaches 5 deg C Appendix B —Effect of airflow on chamber conditions and on surface temperatures of test-specimens FIGURE 2 Experimental data on the effect of airflow on surface temperature of a wirewound resistor —Radial airflow FIGURE 3 Experimental data on the effect of airflow on surface temperature of a wirewound resistor —Axial airflow FIGURE 4 Temperature distribution on a cylinder with homogeneous heat-generation in airflow of velocities 0.5, 1 and 2 m·s APPENDIX C —Effect of specimen emissivity coefficient on temperature rise FIGURE 5 Comparison of the temperature rise as a function of heat-dissipation for thermal white and thermal black specimens subjected to an ambient temperature of 70 ℃ in a chamber with thermal black walls. (Exper-imental values.) APPENDIX D —Effect of wire termination dimensions and material on surface temperature of a component FIGURE 6 APPENDIX E —Heat transfer calculations and nomograms FIGURE 7 Relationship between the surface temperature Ts of the specimen and the heat dissipated P per unit time at the ambient temperature Ts FIGURE 8 Nomogram for evaluation of surface temperatures of the specimen Ts at different ambient temperatures Ts. Average specimen dimension α=0.2 m, emissivity coefficient of the specimen ε2 = 0.7 FIGURE 9 Nomogram for evaluation of surface temperatures of the specimen Ts at different ambient temperatures Ts. Average specimen dimensions α = 0.05 m, emissivity coefficient of the specimen ε2 = 0.7 FIGURE 10 Relation between overtemperature and emissivity coefficient ε2 of the specimen APPENDIX F —Thermal conductivities of common materials APPENDIX C —Measurement of temperature APPENDIX H —Measurement of air velocity APPENDIX J —Measurement of emissivity coefficient FIGURE 11 Wien's displacement law FIGURE 12 Relation between and λ·T APPENDIX K —General block diagram, cold and dry heat tests FIGURE 13
 【中国标准分类号】  A21
 【国际标准分类号】  19_040
 【页数】  40P;A4
 【正文语种】  英语
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