3.3 Test Requirements and Methods

(1) During the temperature test, the temperature change speed between each temperature step shall not exceed 20 ℃ /h. During the test, the relevant test can be carried out only after the tested instrument reaches the temperature stable state as far as possible.

(2) During the high and low temperature storage test of some instruments, the power supply should be disconnected. The power supply shall be kept in the test chamber for at least 4 h.

(3) During the relevant temperature test, the temperature in the test chamber shall be kept as uniform and constant as possible. And the temperature difference shall be less than ± 2 ℃. At the same time, the volume of the test chamber shall be at least 3 times that of the tested instrument. During this test, relevant measures shall be taken to avoid the influence of humidity on the test.

(4) During the temperature test of relevant instruments, it is necessary to carry out the temperature cycle test sequence circle.

(5) During the temperature test under reference conditions: it needs to be carried out at a temperature of 20 ℃± 2 ℃. After the temperature of the tested instrument is stable, turn on the power supply and preheat it according to the preheating time specified by the instrument, then test the relevant technical indicators of the instrument, and cut off the power after the test.

(6) The lower limit temperature shall be arbitrarily selected within the rated service temperature range for the test. During the test, the tested instrument shall be in the energized state, and the test

When the temperature in the test box drops to 10 ℃, the relevant technical indicators of the tested instrument shall be tested after the temperature of the tested instrument is stable, and the power shall be cut off after the test is completed.

(7) Conduct relevant tests at the lower limit temperature specified in the rated service temperature range: the power supply of the tested instrument shall be disconnected, the temperature in the test chamber shall be adjusted to 0 ℃, after the temperature of the tested instrument is stabilized, the power supply shall be turned on, and then the preheating shall be carried out according to the preheating time specified by the instrument. After the preheating is completed, the relevant technical indicators shall be tested, and the power shall be cut off after the test.

(8) The test shall be conducted at the lower limit temperature specified in the limit operating temperature range: during the test, the tested instrument shall be powered on. Adjust the temperature in the test chamber to -10 ℃, test the relevant technical indicators after the temperature of the tested instrument is stable, and cut off the power after the test.

(9) The test shall be conducted at the lower limit temperature specified in the storage temperature range: the power supply of the tested instrument shall be disconnected. Adjust the temperature in the test chamber to -40 ℃ and store it for more than 4 h.

(10) Temperature test under reference conditions: the test personnel need to adjust the temperature in the test chamber to the reference temperature. After the temperature of the tested instrument is stable, turn on its power supply, and then preheat it according to the specified preheating time of the instrument. After preheating, test its relevant technical indicators. During this period, ensure that the instrument does not condense.

(11) The upper limit temperature shall be arbitrarily selected within the rated service temperature range for the test: during the test, the tested instrument shall be powered on, and the temperature in the test chamber shall be adjusted to 30 ℃. After the temperature of the tested instrument is stable, the relevant technical indicators shall be tested, and the power shall be cut off after the test.

(12) The test shall be conducted at the upper limit temperature specified in the rated service temperature range: during the test, the tested instrument shall be powered on, and the temperature in the test chamber shall be adjusted to 40 ℃. After the temperature of the tested instrument is stable, the relevant technical indicators shall be tested, and the power shall be cut off after the test.

(13) The test shall be conducted at the upper limit temperature specified in the limit operating temperature range. During the test, the tested instrument shall be powered on, and the temperature in the test chamber shall be adjusted to 50 ℃. After the temperature of the tested instrument is stable, the relevant technical indicators shall be tested, and the power shall be cut off after the test.

(14) The test shall be conducted at the upper limit temperature specified in the storage temperature range: the power supply of the tested instrument shall be disconnected. Adjust the temperature in the test chamber to 60 ℃ and store it for more than 4 h.

(15) Conduct the test at the upper limit temperature specified in the rated service temperature range: during the test, the tested instrument shall be in the power-off state, adjust the temperature of the test chamber to 40 ℃, after the temperature of the tested instrument is stable, turn on its power supply, and then test its relevant technical indicators. Continue to operate at high temperature for at least 16 h, test relevant technical indicators before the end, and cut off power after the test.

3.4 Test Results

After the above tests are completed, the tested instrument shall be visually inspected. The specific contents to be inspected include: check the instrument surface for rust, damage, cracks and other abnormalities; Relevant identifications and text descriptions shall be kept clear; Movable parts shall be flexible and reliable; Fasteners shall be free from looseness.

4.Conclusion

At present, many fields will involve the use of electronic instruments. The low temperature adaptability and quality of electronic instruments are related to many important production work. In this paper, the requirements of low temperature environment for electronic instruments are analyzed in detail, and a scientific basis for related technologies is provided.