GB/T 2423.27-1981 Basic environmental test procedures for electrical and electronic products Test Z/AMD: Low temperature/low pressure/humid heat continuous comprehensive test method GB/T2423.27-1981 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Basic Environmental Test Procedures for Electrical and Electronic Products Test Z/AMD: Low Temperature/Low Pressure/Damp Heat Continuous Comprehensive Test Method
Determine the adaptability of products in a continuous comprehensive environment consisting of low temperature, low pressure and damp heat. The object of this test is the product installed in the aircraft without temperature control and unpressurized area. 2 General description of the test
GB 2423.27-—81
This standard provides a standard environmental test procedure consisting of low temperature, low pressure and damp heat. First, low temperature and low pressure are combined, then the temperature is increased, and low pressure and damp heat are combined. Finally, normal atmospheric pressure is restored and the test sample is placed in a normal temperature and humidity environment.
This test simulates the conditions encountered by an aircraft during ascent and descent in an unpressurized and temperature-uncontrolled area. When a non-heat dissipating test sample equipped with an elastic seal (such as a plug connector) becomes cold, the seal will harden and the material will shrink. When the surrounding air pressure decreases, the seal may be damaged and cause pressure loss inside the product. When the aircraft descends into a humid atmosphere, frost and ice will form on the cold product surface. As the air pressure rises, the moisture in the air or the flowing water droplets generated by the thaw may invade the interior of the product due to the pressure difference between the inside and outside of the product. After the seal returns to its normal elasticity, the moisture is retained inside the product. Similarly, for equipment that is not sealed but has a very tight lid and no drain hole, water may accumulate inside the equipment. 3 Explanation of test equipment
3.1 The test chamber must be able to meet the requirements specified in the low temperature test method and the low pressure test method and be able to rise from low temperature conditions to 30-35°C within one hour. It must also have the ability to heat up under low pressure conditions and be able to add water vapor at the same time. 3.2 Since water vapor is introduced into this test, which often causes the insulation resistance to decrease, there should be no gaps when the lead wires on the test sample pass through the wall of the tester. Therefore, the lead wires should have a suitable length and be sufficiently sealed and insulated. 3.3 If the test sample has moving parts, the movement of these parts may be hindered by ice inside the test sample, so the test chamber should have electronic or mechanical devices to monitor this kind of movement. 4 Test procedure
4.1 The test sample should be installed in the chamber according to the relevant standards. 4.2 When the test sample is a plug connector, if the relevant standards do not specify, they are plugged in, and the relevant standards should specify the wiring conditions of the multi-way connector.
4.3 If the relevant standards require that the test sample has a functional display during the test or at the end of the test, this display device should be placed in the test chamber together with the test sample.
4.4 Unless otherwise specified in the relevant standards, the test sample should not be powered when the temperature is increased or decreased. 5 Pretreatment
The test sample should be pretreated according to the provisions of the relevant standards. 6 Initial test
The test samples shall be inspected for appearance and tested for electrical and mechanical properties in accordance with the relevant standards. 7 Conditional testbzxZ.net
Promulgated by the General Administration of Standards of the People's Republic of China
National Technical Committee for Environmental Standardization of Electrical and Electronic Products
Implemented on April 1, 1982
The Third Working Group of the National Technical Committee for Environmental Standardization of Electrical and Electronic Products
GB 2423.27-81
The test chamber is at the test room temperature, and the test samples are not packaged, not powered, in the "ready to work" state and placed in the chamber in their normal working position or in accordance with the relevant standards.
7.1 The temperature in the chamber is reduced to the value specified in the relevant standards, and the average rate of temperature change calculated every 5 minutes is not more than 1℃/min. When the test samples reach temperature stability, they can be tested in accordance with the relevant standards. 7.2 The temperature is maintained at the specified value, and the air pressure in the box should be reduced to the value specified in the relevant standards at a rate not exceeding 10 kPa/min, and the test should be carried out in accordance with the relevant standards.
7.3 The pressure is maintained at the specified value, and the box temperature is raised to 30°C or the room temperature (whichever is higher) within one hour at a relatively uniform rate. At the same time, water vapor is added at a rate sufficient to form frost on the test sample. 7.4 When the surface temperature of the test sample reaches between 0°C and 5°C, the pressure in the box should be restored to the indoor air pressure value at a roughly uniform rate within 15 to 30 minutes when the surface begins to defrost. 7.5 After the box temperature reaches 30°C or the room temperature (whichever is higher), the temperature should be maintained for one hour. If the inspection time is longer, the maintenance time should be sufficient for performance testing. The humidity should be maintained at more than 95% to allow condensation to appear on the surface of the test sample. 7.6 The test should be carried out in accordance with the relevant standards. 7.7 If the relevant standards specify, the test steps of 7.1 to 7.6 may be repeated in sequence, the number of repetitions shall be as specified in the relevant standards, and the state of the test sample in the box shall not be changed during the repeated tests. 8 Recovery
Unless otherwise specified in the relevant standards, the test sample shall remain in the test box together with the connecting lead wire until the internal temperature of the test sample reaches the standard test atmosphere.
9 Final test
The test sample shall be subjected to visual inspection and electrical and mechanical performance tests in accordance with the relevant standards. Details to be given in the adoption of this standard
When the relevant standards adopt this test method, the following items shall be specified a. Low temperature value and low pressure value (selected from the low temperature test method and the low pressure test method). b. Pretreatment.
Electrical and mechanical tests to be performed before the core and condition test. d. The installation method of the test sample in the test box and any special requirements. For example, the matching and wiring of the plug and socket connector. e. Electrical and mechanical tests to be performed under low temperature and low pressure conditions. f. g. Electrical and mechanical tests to be performed at high and low temperatures. g. Number of cycles of low temperature/low pressure/humid heat. h. Electrical and mechanical tests to be performed after recovery. 282
See Clauses 7.1 and 7.2
See Chapter 5
See Chapter 6
See Clauses 4.1 and 4.2
See Clauses 7.1 and 7.2
See Clause 7.6
See Clause 7.7
See Chapter 9
1. This standard should be used together with the following standards: GB2423.27--81
GB2421-81 "General rules for basic environmental testing procedures for electric and electronic products"
GB2422-81 "Terms and terms for basic environmental testing procedures for electric and electronic products"
GB2424.15-81 "Guidelines for temperature/low pressure comprehensive test for basic environmental testing procedures for electric and electronic products" 2. This standard directly quotes IEC Standard Publication 68-2-39 Test Z/AMD: Combined sequential cold low air pressure and damp heat test, first edition in 1976.
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