Application comparison of test methods in high and low temperature test chamber

1. Non-heat-dissipation test sample and heat-dissipation test sample: After the temperature of the test sample is stable during the condition test, when measured under free air conditions (that is, without forced air circulation), the hottest spot temperature on the surface of the test sample is 5 degrees higher than the ambient air temperature The above are considered to be heat-dissipating test samples, and vice versa, non-heat-dissipating test samples. For all storage tests and tests that are not energized or loaded during the test, the test samples are non-heat-dissipating test samples, and the test adopts the low temperature test method.

2. Non-heat-dissipating test sample: temperature change test in a sudden change of  high and low temperature test chamber (the former is a rapid temperature change test chamber and the latter is a high and low temperature test chamber). Temperature mutation test Aa: First adjust the temperature of the test chamber to the specified test temperature, and then put the test sample with room temperature. This test method is suitable for the known temperature mutation that does not produce any operation on the test sample. Temperature gradient test Ab: First put the test sample with room temperature into the test box at the same room temperature, and then turn on the cold source to gradually cool the temperature in the box to the specified test temperature. If the test sample is too large or too heavy, or because For complicated functional test wiring, test Ab should also be used when it cannot be put into a low temperature box without frosting during mutation test.

3.  high and low temperature test chamber Heat dissipation test sample with and without forced air test: The method of ensuring uniformity fluctuations in the industry is to adopt the wind circulation mode. The motor drives the fan to generate wind circulation to form the wind speed flow direction. The test without forced air circulation simulates free air A type of condition-affected test, which is more suitable for the test of heat dissipation test samples. The test with forced air circulation is when it is difficult or impossible to guarantee the specified test conditions without forced air circulation. There are two types of test method Ad available: forced air Methods: A and B. Method A is used when the test box is large enough to meet the test requirements without forced air circulation, but the specified low temperature cannot be maintained without forced air circulation, that is, the refrigeration or heating of the high and low temperature test box When forced air circulation is required.