"Basic Environmental Test Regulations for Electrical and Electronic Products"

"Basic Environmental Test Regulations for Electrical and Electronic Products"

Test Cb: Constant damp heat test method for equipment

GB 2423.9--89

Basic environmsental testing procedures for electric and electronic products

Test Cb: Damp heat ,steady state,primarily for equipment

1 Subject content and scope of application

This standard specifies the basic environmental test procedures for electrical and electrical products: the constant damp heat test method for equipment.

This standard is applicable to the determination of electrical and electronic products. It mainly refers to the adaptability of the equipment to be used and stored under damp and hot conditions. This test is mainly used to observe the influence of the test sample under a constant temperature, no condensation, and a high humidity environment for a specified time.

This standard is particularly applicable to large-scale equipment or equipment that may be complicatedly connected to the test equipment outside the test room during the test. This connection requires a certain assembly time. During installation, it is not necessary to preheat or maintain specific test conditions.

This standard includes several different temperature and humidity severity levels for selection and application. The selection of the severity level should be based on the use environment of the test sample and its working characteristics.

This standard can be applied to heat-dissipating and non-heat-dissipating test samples. When the heat-dissipating test sample is tested, the surrounding temperature and humidity of the test sample will change due to the influence of the emitted heat. At this time, the measurement of these two parameters should be carried out according to the measurement method of free air conditions specified in GB2423.2.

2 test chamber (chamber) requirements

2.1 Structural requirements of the test chamber (chamber)

A. The indoor temperature and humidity conditions are monitored by a sensor device installed in the work space. For the test of heat dissipation test sample, the installation position of the sensor should also refer to the description in Article 2.7.2 of GB2422.

B. The temperature and relative humidity of the working space are required to be kept within the nominal value and its specified tolerance range. At the same time, the influence of test samples should be considered. The temperature errors specified in this standard include measurement errors and slow changes in temperature. For non-heat-dissipating test samples, the temperature error also includes the temperature uniformity of the working space. In order to ensure that the relative humidity does not exceed the allowable error, it is necessary to keep the temperature difference between any two points in the working space within a narrow range at any moment, and it is generally specified that it does not exceed 1°C. Similarly, short-term temperature fluctuations must be kept within a narrow range. For the heat dissipation test sample, the test conditions are affected by the heat dissipation of the test sample itself, which will make the temperature and humidity conditions near it somewhat different from the data measured at the specified position in 2.1a of this standard.

C. The condensed water should be discharged out of the box (chamber) continuously and cannot be reused before it is purified.

D. The condensed water on the inner wall and top of the test box (chamber) cannot drip onto the test sample.

E. The resistivity of water to maintain indoor humidity is not less than 500Ω. m.

F. The test sample cannot be exposed to direct heat radiation from the heating element of the test box (chamber).

G. The moisture sprayed by the spray system in the test box (chamber) should be far away from the test sample and should not directly rush to the surface of the test sample.

2.2 Test of heat dissipation test sample

The volume of the test box (chamber) should be at least 5 times the total volume of the test sample.

The distance between the test sample and the wall of the box (chamber) should be selected in accordance with GB2423.2 Appendix A (reference). The wind speed in the box (chamber) cannot exceed 1.0m/s.

2.3 Installation of test samples

The structure of the mounting frame or support frame of the test sample should simulate the real conditions in use as much as possible.

If there are no other regulations, the influence of the sample mounting frame on the moisture and heat exchange between the test sample and the surrounding space should be reduced to the extent that the relevant standards may also specify a dedicated mounting frame.

3 severity level

The test severity level is a combination of temperature, relative humidity and time, and is specified by relevant standards.

The conditions of temperature and relative humidity can be selected from the following combinations:

The recommended test time is: 2, 4, 7, 10, 21d.

4 Test procedure

4.1 Initial inspection

The test sample shall be subject to visual inspection and electrical and mechanical performance testing in accordance with relevant standards.

4.2 Condition test

a. Under the test conditions of the same temperature and humidity in the test box (chamber) and the laboratory, send the test samples of the same temperature into the test box (chamber). The test samples should be unpackaged, not energized or ready to work, press It is installed on the bracket at the normal working position, and other installation methods can also be specified by relevant standards. In some cases, for example, when a large test box (chamber) is used for continuous testing, it is permissible to send the test sample directly into the test box (chamber) that has reached the test conditions. In this case, we must try to prevent the test Condensation occurs when the sample is sent into the room.

B. Then, adjust the temperature in the test box (chamber) to a predetermined severity level, and the time should ensure that the test sample reaches a stable temperature. The temperature change rate should not exceed 1℃/min (average value within 5min) within 5min or according to relevant standards. In order to prevent condensation, the humidity should not increase during this time.

C. Then, slowly adjust the humidity to a predetermined severity level within 2 hours.

D. The time for the test sample to be tested under the test conditions shall be in accordance with the relevant standards, and the calculation of the test time shall start after the prescribed conditions are reached.

E. If the relevant standards require the test samples to be energized and/or work in the conditional test phase, the relevant standards shall specify the working conditions and the energization or working time of the test samples.

F. Then, samples can be entered according to the requirements of relevant standards

4.3 Intermediate detection

Relevant standards may propose testing when the test sample is still in the test chamber (chamber) during or at the end of the conditional test. If such testing is required, the relevant standards should specify the items to be tested and the time to complete these measurements.

During this test, the test sample should not be taken out of the room.

The recovery processing specified in Article 4.4.

A. After the condition test, the relevant standards may stipulate that the test sample should be recovered under normal test atmospheric conditions (see 4.3 in GB2421) or under controlled recovery conditions (see 4.4.1 in GB2421).

When applying controlled recovery conditions for recovery processing, the test sample can be transferred to another test box (chamber) or performed in the original test box (chamber).

For the former case, the transfer time of the test sample should be as short as possible.

In the latter case, the conditions in the test chamber (chamber) should be adjusted to a relative humidity of 73%~77% within 0.5h, and then the temperature should be adjusted to the laboratory temperature (+15~+35) within 0.5h. ℃), the error is within +1℃.

B. The recovery time is 1~2h from the time when the specified recovery conditions are reached.

The test sample with a large thermal time constant should be recovered for a time sufficient to make it reach temperature stability.

C. Relevant standards can propose other restoration conditions by themselves.

4.5 detection

The test sample shall be subjected to visual inspection and electrical and mechanical performance testing in accordance with relevant standards.

5 The detailed rules that should be put forward when the relevant standards refer to this standard

A. Necessary special installation structure (see Article 2.3 of this standard);

B. Test severity level: temperature, relative humidity, time (see Chapter 3 of this standard);

C. Initial test items (see Article 4.1 of this standard);

D. The operating requirements of the test sample during the conditional test period (see Article 4.2e of this standard);

E. Intermediate measurement items (see Article 4.3 of this standard);

F. Recovery conditions (see Article 4.4 of this standard);

G. Test items (see Article 4.5 of this standard).

  Additional information:

This standard was proposed by the National Standardization Technical Committee on Environmental Conditions and Environmental Tests for Electrical and Electronic Products.

This standard is under the jurisdiction and drafting of Guangzhou Electrical Apparatus Research Institute.

The main drafters of this standard are Wei Zhuyun, Jia Xuemao, Li Mingfang, Wang Xiurong, Lu Xiangqin.