Design of temperature change test box for high and low temperature test box: GB / T 2423.22-2002 temperature change test Na, Nb and Nc include the alternation of high and low temperature periods, the conversion from one humidity to another temperature is clearly specified From room temperature to the first condition test temperature, and then to the second condition test temperature and back to room temperature, this program constitutes a test cycle, high and low temperature test chamber test parameters: room temperature, high temperature, low temperature, exposure, two extreme temperatures The time interval between exposures, the number of test cycles, high temperature and low temperature refer to the ambient temperature, these temperatures will be reached by most test samples, but the time is lagging, only under exceptional circumstances, the test article is required to be stored in normal or Outside the operating temperature range, the temperature change test is accelerated, because the number of sharp changes in temperature in a given time is greater than what happens under field conditions.
The purpose of the high and low temperature test chamber test and the choice of test method: the temperature change test is not a test that accurately simulates the field conditions. The purpose of the temperature change test is to stress the test samples in order to determine whether they are designed or manufactured correctly. Situation, it is recommended to conduct a temperature change test to evaluate the electrical performance during temperature change, test Nb to evaluate the mechanical performance during temperature change, test Nb to evaluate the electrical performance after a specified number of rapid temperature changes, test Na or test Nc, to evaluate the adaptability of the component to the resistance to artificial stress, using the test Na or test Nc, the temperature change test specified in the standard, is not used to evaluate the material constant or electrical performance when working under two extreme temperatures in a stable state Difference.
Selection of the exposure time of the high and low temperature test chamber: The exposure time depends on the thermal time constant of the test sample (or its vulnerable part) when it reaches the temperature of the surrounding space or tank, so it is important to understand the thermal time constant of the test sample, because The internal and external thermal time constants of large test samples (equipment) may differ greatly. Therefore, it is appropriate to consider the thermal time constants in the internal or vulnerable parts. The thermal time constant of the test sample depends on the surrounding medium (in the test Na and Nb are air, in the test Nc is water or other liquids) the nature and speed of movement, therefore, it is hoped that it will be measured by the test in the actual surrounding conditions during the test.
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