Selection requirements for high and low temperature alternating test chambers
1. Reproducibility of environmental conditions
It is an elusive job to accurately and accurately reproduce the environmental conditions that exist in nature in the laboratory. However, within a certain tolerance plan, people can correctly and similarly imitate the external environmental conditions that the engineering products are subjected to during use, storage, transportation, etc. This paragraph is summarized in the words of the project, that is, "test equipment." The environmental conditions surrounding the tested product (including the channel environment) should meet the environmental conditions and tolerance requirements of the product test standards. For example, the temperature box used for military product testing should not only meet the high temperature and low temperature test values and test time of the national military standard GJB150.3-86 and GJB150.4-86 according to the different types of products, but also meet the test. The requirements for temperature field uniformity and temperature control accuracy in the standard. As long as this is the case, talent ensures the reproducibility of environmental conditions in environmental testing.
2. Repeatability of environmental conditions
A high and low temperature alternating test chamber equipment may be used for multiple tests of the same type of product, and one engineered product may also be tested in different environmental test equipment, in order to ensure that the same product is in the same test standard. The comparability of the test results obtained under the environmental test conditions of the rules must require the environmental conditions supplied by the environmental test equipment to be reproducible. That is to say, the stress levels (such as thermal stress, oscillating stress, electrical stress, etc.) applied to the product under test by the environmental test equipment are consistent with respect to the requirements of the same test standard.
The repeatability of the environmental conditions supplied by the environmental test equipment is guaranteed by the verification of the metrological verification part of China according to the verification procedures formulated by the technical supervision agency of China. To this end, it is necessary to require the environmental test equipment to meet the technical objectives and accuracy objectives of the verification procedures, and not exceed the time limit of the verification period in use time. In addition to meeting the technical goals of excitation force, frequency planning, and load capacity, it is necessary to meet the requirements of the lateral oscillation ratio, mesa acceleration uniformity, harmonic distortion ratio, and accuracy target in the verification procedure. The requirements, and the use period after each verification is two years, after two years of necessity, it is necessary to pass the test before passing the test.
3. Measurable control of environmental condition parameters
The environmental conditions supplied by any environmental test equipment must be observable and controllable, not only to constrain the environmental parameters within a certain tolerance plan, but also to ensure the reproducibility and repeatability requirements of the test conditions. It is also necessary to proceed from the safety of product testing in order to avoid damage to the tested product due to out of control of environmental conditions, resulting in unnecessary losses. The accuracy of the general requirement parameter test in various test standards should not be lower than one third of the error of the test condition.