SN EN 60068-3-1 : 1999

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-1
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 degree C
            in a chamber with thermal black walls.
            (Experimental 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
            of the specimen and the heat dissipated per
            unit time at the ambient temperature
FIGURE 8 Nomogram for evaluation of surface temperatures
            of the specimen at different ambient
            temperatures. Average specimen dimension = 0.2m,
            emissivity coefficient of the specimen = 0.7
FIGURE 9 Nomogram for evaluation of surface temperatures
            of the specimen at different ambient temperatures.
            Average specimen dimension = 0.05 m, emissivity
            coefficient of the specimen = 0.7
FIGURE 10 Relation between overtemperature and emissivity
            coefficient of the specimen
APPENDIX F - Thermal conductivities of common materials
APPENDIX G - Measurement of temperature
APPENDIX H - Measurement of air velocity
APPENDIX J - Measurement of emissivity coefficient
FIGURE 11 Wien's displacement law
FIGURE 12
APPENDIX K - General block diagram, cold and dry heat tests
FIGURE 13

Covers background information on basic environmental testing procedures - Cold and dry heat tests.