Environmental testing for electrical and electronic products - Part 2: Test methods - Test A: Low temperature range - The low temperature test specified in this part of GB/T 2423 is applicable to non heat dissipation and heat dissipation test samples. There is no substantial difference between Test Ab and Test Ad and earlier versions. The main purpose of adding Test Ae is to detect equipment that requires power to operate throughout the entire test process, including cooling adjustment. The purpose of this low-temperature test is limited to determining the ability of components, equipment, or other products to be used, transported, or stored in low-temperature environments. This low-temperature test cannot be used to evaluate the ability of the test sample to withstand temperature changes and its ability to operate in temperature changing environments. In this case, GB/T 2423.22 should be used. This low-temperature test method is subdivided into the following categories:----- Non heat dissipation test sample low-temperature test: · Test Ab, temperature gradient. Low temperature test of heat dissipation test sample: Test Ad, temperature gradient· Test Ae, temperature gradient, and the test sample is energized throughout the entire test process. The test methods provided in this section are usually used for test samples that can achieve temperature stability during the test period