Basic environmental testing procedures for electric and electronic products--Tests A:Cold
Some standard content:
National Standard of the People's Republic of China
Basic environmental testing procedures for electric and electronic productsTests A: Cold
GB2423.1—89
Generates GB 2423 1---81
This standard is equivalent to the international standard LEC 68-2-1 Basic Environmental Testing Procedures Test A, Cold (1974 Edition) and its first supplementary document [EC 68-2-1A (1978). 1 Subject content and scope of application
This standard specifies the basic environmental testing procedures for electric and electronic products Tests A: Low temperature test method. This standard applies to low-temperature tests of non-heat-dissipating and heat-dissipating electrical and electronic products (including components, equipment and other products 2. 2 Overview || tt || 2.1 This standard is limited to assessing or determining the adaptability of electrical and electronic products to storage and (or) use under low-temperature environmental conditions, and cannot be used to evaluate the resistance and working ability of test samples during temperature changes. In this case, GB2423.22 Basic Environmental Test Procedure for Electrical and Electronic Products Test N, Temperature Change Test Method, should be adopted. 2.2 This test method is usually used for test samples that can achieve temperature stability during the conditional test. 2.3 During the test, the test sample at room temperature is put into the test. When the test sample is actually used with a specific mounting rack, these mounting racks should be used during the test. 2.4 The test duration is calculated from the time the test sample reaches temperature stability: In special circumstances, if the test sample cannot achieve temperature stability during the conditional test, the test duration starts when the test chamber (room) reaches the specified test temperature. Calculation. 3 Classification and block diagram of low temperature test methods
3.1 Low temperature test methods are divided into:
Non-heat dissipation test sample low temperature test: Test Aa temperature sudden change: Test Ab temperature gradual change;
Heat dissipation test sample low temperature test: Test Adb.
Temperature gradual change.
3.2 The block diagram of low temperature test method classification is as follows, approved by the Ministry of Machinery and Electronics Industry of the People's Republic of China on February 28, 1989 and implemented on January 1, 1990
Non-heat dissipation test sample
A Sudden temperature change
Ab Gradual temperature change
Test sample without artificial cooling
No forced air
Cyclic test
(9.7.1.13
4 Comparison of application of various test methods
With forced air
Cyclic test
(9.7.1.2)
4.1 Non-heat dissipation test sample and heat dissipation test sample GB 2423.1—89 Test A: Temperature and humidity test sample separated and combined (9.7.2.1) Unobstructed air test sample (8.7.1.1) Heat dissipation test sample Temperature change test sample with artificial cooling Cooling system and test sample not separated (9.7.2.1) Air test sample with obstructed air (9.7.1.2) 4.1. 1. After the temperature of the test sample reaches stability during the conditional test, when measured under free air conditions (i.e., without forced air circulation), if the hottest point temperature on the surface of the test sample is more than 5°C higher than the surrounding atmospheric temperature, it is considered to be heat dissipating, otherwise it is a non-heat dissipating test sample. 4.1.2 During all storage tests and tests without power or load, the test samples are non-heat dissipating test samples, and the test adopts the low temperature test method Ab.
4.2 Temperature Sudden Change Test and Temperature Gradient Test of Non-Heat Dissipating Test Samples 4.2.1 Temperature Sudden Change Test Aa: First, the temperature of the test box (room) is adjusted to the specified test temperature, and then the test sample with the case temperature is placed. This test method is applicable when it is known that the temperature sudden change will not cause damage to the test sample. 4.2.2 Temperature Gradient Test Ab: First, the test sample with room temperature is placed in the test box (room) which is also at room temperature, and then the cold source is turned on to gradually cool the box (room) temperature to the specified test temperature. This test method will not cause damage to the test sample due to temperature changes. If the test specimen is too large or too heavy, or due to complex functional test wiring, it is not possible to place it in a low-humidity chamber without frost formation during the sudden change test, test Ab should also be used. 4.3 Tests of heat dissipation test specimens with and without forced air circulation 4.3.1 Test without forced air circulation: This is a test that simulates the influence of free air conditions. This test method is a better method for testing heat dissipation test specimens.
4.3.2 Test with forced air circulation: This test method is used when it is difficult or impossible to ensure the specified test conditions without forced air circulation. Two methods with forced air circulation in test method Ad can be used: method A and method B. Method A is used when the test chamber is large enough to meet the test requirements without forced air circulation, but the specified low temperature cannot be maintained without forced air circulation in the chamber, that is, when the cooling (or heating) of the test chamber requires forced air circulation. Method B is used in this case, that is, when the test chamber is too small or for other reasons, it cannot meet the test requirements without forced air circulation. 5 Test equipment
5.1 The working space of the test box (room) shall be able to provide the temperature conditions specified in Article 6.1, and strong air circulation can be used to maintain uniform temperature.
GB 2423.1-89
5.2 In order to limit the influence of radiation, the difference between the temperature of each part of the inner wall of the box (room) and the specified test temperature shall not exceed 8% (calculated in Kelvin temperature), and the test sample shall not be directly radiated by any heating and cooling elements that do not meet the above requirements. 6 Severity
The severity of the test mainly depends on the temperature level and duration of the test. The relevant standards should be selected from the following values:
6.1 Temperature
The test temperature should be selected from the following values: -65, 55, -40, -25, -10. -5, +5℃. The allowable deviation range of the test temperature is ±3℃. 6.2 Duration
After the temperature of the test sample reaches stability, if a certain period of low temperature condition test is required, the duration should be selected from the following time:
2.16.72,96h.
If the purpose of the test is only to check whether the test sample can work normally at low temperature, the test time is limited to the test sample temperature reaching stability; but in any case, the duration should not be less than 30min. When this standard is used as a related test related to low temperature durability or reliability, the duration required for the test shall be specified by the relevant standards.
7 Specific provisions to be made when applying this standard to relevant standards 7.1 The relevant standard developers can select the following parameters according to the guidance of GB2424.1-87 "Basic Environmental Test Procedures for Electrical and Electronic Products: High and Low Temperature Test Guidelines":
a. The rate of temperature change in the test chamber;
The time when the test sample is placed in the test chamber! bzxZ.net
The time when the test sample is exposed to the test conditions at the beginning of the test C
The time when the test sample is energized or loaded. 7.2 The relevant standards shall give the following applicable details of the low temperature test method, a.
Preconditioning:
Initial test
Details of installation or support;
Condition of the test sample (including cooling system) during the conditional test! Severity (temperature and test duration): Measurement and (or) load recovery during the conditional test (if not restored under standard conditions): Final test
Any changes to the test procedure agreed by both parties. 8 Test A and: Test of the ability of non-heat dissipation test samples to pass temperature changes 8.1 Purpose
To provide a standard test procedure to determine the adaptability of non-heat dissipation electrical and electronic products (including components, equipment and other products) to be stored and used at low temperatures without causing damage by sudden temperature changes. 8.2.1 The technical standard is to put the test sample at room temperature into the test box with the temperature specified in the relevant standard. GB 2423. 189 8.2.2 After the test sample reaches temperature stability, it is kept for a specified duration under this condition. 8.2.3. The test sample is usually in a non-working state. 8.2.4 This test usually uses weak forced air circulation. B.3 Test equipment The test equipment should meet the requirements of Chapter 5 of this standard. Test Aa usually uses equipment with strong forced air circulation. B.4 Severity
The severity of the test depends mainly on the temperature level used for the test and the duration of the test, and its value should be selected from Chapter 6. 8.5 Pretreatment
Perform in accordance with the requirements of the relevant standards.
8.6 Initial inspection
Perform visual inspection and electrical and mechanical performance inspection of the test samples in accordance with the relevant standards. 87 Conditional test
8.7.1 Adjust the temperature of the test box (chamber) to the specified test temperature, and then put the test samples under the test room temperature into the test box (chamber) in the normal position or other regulations without packaging, power supply, and "ready to use" state. When the test samples are actually used with a specific mounting frame, these devices should be used together during the test. 8.7.2 Restore the temperature of the test box (chamber) to the specified test temperature and allow the test samples to reach temperature stability. 8.7.3 For the operational test, the test samples must be powered on or electrically loaded in accordance with the relevant standards, and checked to determine whether the specified functions can be achieved.
If the relevant standard requires otherwise, the test sample shall be in operation according to the specified working cycle and load conditions (if applicable), or not powered on.
Note: At this time, even if the test sample is in operation or under negative conditions, as long as the surface temperature does not exceed 5% of the test temperature, it is considered to be non-heat dissipated. 8.7.4 The test sample is kept at this temperature for the time specified in Article 6.2, and the duration should be calculated from the time when the temperature reaches stability. Note: For some small test samples, it is not necessary to check whether the temperature has reached stability by measurement. 8.7.5 If the relevant standard requires intermediate testing, proceed to Article 8.8. 8.7.6 After the conditioning test is completed, the test sample should be restored to its original state. For test samples that are powered on or loaded with electrical loads, the power should be stopped or the load should be removed before resuming the procedure.
8.8 Intermediate testing
The relevant standard may stipulate that loads and (or) measurements should be added during or at the end of the conditioning test (the test sample is still in the test chamber). If necessary, the items and time of measurement should be specified. During the measurement, the test samples shall not be taken out of the test box (chamber). Note: ① The test samples shall not be taken out of the test box (chamber) during the conditioning test, and shall be put back into the test box (chamber) after the measurement before recovery. ② If the performance of the test samples at a specific time is required before the end of the duration, a batch of test samples shall be added for each specific time, and recovery and final measurement shall be carried out. Each batch of test samples shall be carried out separately. 8.9 Recovery
8.9.1 The test samples shall be recovered under standard atmospheric conditions until thawed. Note: When the standard atmospheric conditions are not suitable for the test samples, other recovery conditions may be specified in the relevant standards. 8.9.2 In order to remove water droplets, the test samples may be shaken by hand or blown with room temperature air for a short time. 8.9.3 When the test samples are recovered under standard atmospheric conditions, the recovery time shall be sufficient for them to reach temperature stability, at least 1 hour. When several test samples are tested simultaneously and a recovery time of 1 hour is sufficient, the maximum recovery time is 2 hours, and all measurements must be completed before this time.
8.9.4 If the relevant standards require, the test sample shall be powered or loaded during the recovery period and its performance shall be measured continuously. 8.10 Final inspection
The test sample shall be inspected for external specifications and electrical and mechanical properties in accordance with the relevant standards. 8.11 When the relevant standards adopt this test method, specific provisions shall be given for the applicable items in Article 6.2. GB 2423.1—89
9 Test Ab Low-temperature test of non-heat dissipation test sample with gradual temperature change 9.1 Purpose
Provide a standardized test procedure to determine the adaptability of non-heat dissipation electrical and electronic products (including components, equipment or other products) for low-temperature storage and (or) use.
9.2 General description
9.2.1 This test is to place the test sample with room temperature into a test chamber with room temperature, and then adjust the chamber temperature to the temperature value specified in the relevant standards.
9.2.2 This test method shall also meet the requirements of Articles 8.2.2 to 8.2.4 of this standard. 9.3 Test equipment
The test equipment shall meet the requirements of Chapter 5 of this standard. Test Ab usually uses equipment with forced air circulation. 9.4 Severity
The severity of the test is mainly determined by the test temperature level and the test duration. The value should be selected from Chapter 6. : 9.5 Pretreatment
Perform in accordance with the provisions of the relevant standards.
9.6 Initial inspection
Perform visual inspection and electrical and mechanical performance inspection of the test samples in accordance with the provisions of the relevant standards. 9.7 Conditioning test
9.7.1 Place the test samples at room temperature in the test chamber (room) without packaging, without power, ready for use: connected to the correct position or other provisions. At this time, the temperature of the test chamber (room) is also room temperature. When the test sample is to be used together with a specific mounting frame, the test should be carried out together with these mounting frames. 9.7.2 Turn on the cold source to reduce the temperature of the test box (room) to the specified test temperature, and give time for the test sample to reach temperature stability. The temperature change rate in the box (room) is not more than 1℃/min (not more than the average value of 5min). The test ambient temperature should be measured in accordance with the provisions of Article 2.7 of GB2122-81 Basic Environmental Test Procedures for Electrical and Electronic Products.
9.7.3 For the workability test, the inspection and test shall be carried out in accordance with the provisions of Article 8.7.3 of this standard. 9.7.4 The test sample shall be exposed to the specified low temperature conditions for the test, and the duration shall comply with the provisions of Article 8.7.4. 9.7.5 If the relevant standards have requirements, the intermediate test shall be carried out in accordance with the provisions of Article 9.8. 9.7.6 At the end of the conditioning test, the test sample remains in the test chamber (room), and the temperature of the test chamber (room) is raised to the normal test atmospheric conditions. The rate of temperature change in the chamber (room) is not more than 1°C/min (not more than the average value of 5 minutes). 9.7.7 After the end of this stage, the test sample shall be subjected to a recovery procedure. The recovery can be carried out inside the chamber (room) or outside the chamber (room), whichever is appropriate. If the test sample is in operation or under load during the conditioning test, the power supply shall be stopped or the load shall be removed before the temperature is raised. 9.8 Intermediate testing
The relevant standards may require that the test sample be subjected to intermediate testing according to the provisions of Article 8.8 during or at the end of the conditioning test. 9.9 Recovery
Recovery shall be carried out in accordance with the procedures specified in Article 8.9 of this standard. 9.10 Final testing
Final testing shall be carried out in accordance with the provisions of Article 8.10 of this standard. 9.11 When the relevant standard adopts this test method, specific provisions shall be given for the applicable items in 7.2. 10 Test Ad; Heat dissipation test sample temperature gradient low-temperature test 10.1 Purpose
Provide a standard test procedure to determine the applicability of heat dissipating electrical and electronic products (including components, equipment or other products) for use under low temperature conditions.
10.2 General description
GB 2423.1-89
10.2.1 This test method shall also meet the descriptions of Sections 2.2.2.3, 2.4 and 9.2.1 of this standard. 10.2.2 The relevant standard must explain the function of the test sample, and attention should be paid to whether the cooling device of the test sample complies with the provisions of the relevant standards. 10.2.3 The designed test conditions shall be able to simulate the effect of subjecting the test sample to "free air" conditions, and use a mounting frame with specified heat conduction characteristics. The heat conduction characteristics of the test sample shall comply with relevant regulations. 10.2.4 This test method is preferably used without forced air circulation; however, when it is difficult or impossible to meet the test conditions without forced air circulation, forced air circulation can be used. Appendix A is an integral part of this test method. 10.3 Test equipment and mounting frame
10.3.1 The test equipment shall meet the requirements of Chapter 5 of this standard. The box wall should be close to thermal black. The radiation coefficient shall not be less than 0.7. 10.3.2 The overflow in the test box (slaughter) shall be detected by a temperature sensor, and the placement of the temperature sensor shall be in accordance with the provisions of "ambient temperature" (Article 2.7) in GB2422. 10.3.3 In the case of no forced air circulation test, the test box (room) shall be large enough compared with the size of the test sample and its total heat dissipation, and shall be large enough to simulate the influence of "free air" conditions. If the minimum distance between any surface of the test sample and its corresponding box (room) wall is greater than 15cm, and the ratio of the box (room) volume to the test sample volume is not less than 5:1 (electronic, instrument, low-cost electrical products) or 10:1 (television, transformer, high-voltage electrical appliances and other electrical products), it is considered to meet the requirements of "free air" conditions. Note: If the mounting frame or connector is tested together with the test sample.The volume of the test sample should include its volume. During the test, the test sample should be as close to the center of the test box as possible, so that there is as much space as possible between any part of the test sample and the box wall. When multiple test samples are tested at the same time, there should be enough distance between each test sample to avoid mutual influence. 10.3.4 When the test is carried out in a test box (room) with forced air circulation, the wind speed should be as low as possible. 10.3.5 When the relevant standard stipulates a working cycle system for the test sample, measures must be taken to keep the test temperature stable. When the test samples are some components and the distribution of the components with load in the test box (room) at any time is quite uniform, the method of staggered load of components can usually be used to keep the test temperature stable.
Note: For the test of the test sample with a working cycle, the temperature of the test box (air) should not drop below the specified temperature during the no-load period (see Figure 2). 10.3.6 The thermal conductivity and other relevant characteristics of the mounting frame and connecting parts of the test sample should be specified in the relevant standards. If nothing is known about the characteristics of the mounting frame, the thermal conductivity of the mounting frame should be high. 10.4 Severity
The severity of the test is mainly determined by the test temperature level and the test duration, and its value should be selected from Chapter 6. 10.5 Pretreatment
Perform in accordance with the provisions of the relevant standards.
10.6 Initial inspection
Perform visual inspection and electrical and mechanical performance inspection and measurement of the test samples in accordance with the relevant standards. 10.7 Conditioning test
: 10.7.1 Test samples without human cooling
0.7.1.1 Test without forced air circulation
a. First place the test sample with room temperature in a test box (room) with the same temperature. The placement of the test sample is in accordance with the provisions of 9.7.1.
h. Adjust the box (room) temperature to the temperature specified in the test according to the temperature change rate specified in 9.7.2, and allow the test sample to reach temperature stability.
Power on or load the test sample: and check to determine whether the specified function can be achieved. The test sample should be kept in operation according to the working cycle and load conditions (if applicable) specified by the American standard. d. Then, expose the test sample to low temperature conditions, and the duration should comply with the provisions of Article 8.7.4. GB 2423.1—89
e. If the relevant standard requires intermediate testing, it should be carried out in accordance with the provisions of Article 10.8. f. At the end of the conditional test, the power supply or load of the test sample should be stopped or the load should be removed, and then the box (room) temperature should be adjusted to the standard atmospheric condition range of the test in accordance with the provisions of Article 9.7.6. 10.7.1.2 Test with forced air circulation When the specified test conditions cannot be met without forced air circulation, if forced air circulation is used, there are two methods as follows: Method A:
Method A is used when the test chamber (room) is large enough to meet the test requirements without forced air circulation, but the ambient temperature in the chamber (room) can only be maintained with the help of air circulation.
Note that the ambient temperature is the specified test temperature. This method is to place or install the test sample in a test chamber (room) at room temperature, and when the circulating airflow and cooling system in the test chamber (case) are turned off, the load specified for low temperature test is applied to the test sample. When the test sample reaches temperature stability, use appropriate detection equipment to measure the temperature T of several representative points, and record the temperature rise AT1 of each point. Then, start the ventilation device of the test chamber (air) to circulate the air. Once the sample reaches temperature stability again, measure the temperature rise T1 of each representative point. If the temperature rise of these representative points, when there is no forced air circulation and when there is forced air circulation, the difference between them (△T1-△T1) is greater than 3℃ or other values specified in the relevant standards, it means that the air circulation speed is too high and should be reduced until AT1-AT1 meets 3 or other values specified in the relevant standards. If it is impossible to meet this requirement, method B should be used. After that, turn on the power supply of the cooling device of the test box (room) for cooling, and the test starts immediately. The test environment temperature shall be measured in accordance with the relevant provisions of GIB2422* "Ambient temperature of heat dissipation test sample". The test will be carried out according to the test method without forced air circulation in Article 10.7.1.1. The temperature conditions of the three test stages of Method A are shown in Figure 1. Method B:
Method B is used in situations where Method A cannot be applied, such as when the volume of the test chamber used for the test is not large enough to meet the test requirements, and when the test requirements cannot be met without forced air circulation. It is based on the assumption that the difference △T between the temperature of the hottest point on the test sample and the ambient air temperature under free air conditions is almost independent of its ambient temperature. This assumption is only applicable when AT, <25C. If the correction of the figure in Appendix A is applied, the △T1 value can be expanded to 80C. The correction includes convection error and radiation error. When the temperature difference △T exceeds 80℃, the effectiveness of method B has not been confirmed. Install the test sample properly in the test room so that it is not affected by interference such as sunlight and airflow. Make it withstand the load case specified in the low temperature test at the test environment temperature. When the temperature reaches stability, measure the temperature of the hottest point. For larger or more complex test samples, measure the temperature of several representative points and record the temperature rise △T at each point. The test procedure of method R is:
First, in the test case, without the interference of sunlight and airflow, test the correctly installed Apply the specified load to the test sample, and after the temperature stabilizes, measure the temperature T of the hottest point on the surface of the test sample (several representative points should be measured for larger or more complex ones), and record the temperature rise ATie
at each point. If AT1 is less than 25C, conduct the test according to the test method without forced air circulation in Article 10.7.1.1 of this standard. If △T1 is greater than 25℃, the surface temperature T of the test sample should be corrected according to the requirements of Appendix A based on the specified test temperature, and T. is corrected to T. When the test sample and the box are at room temperature, place the test sample in the box, then power on the test sample or add an electrical load according to the relevant standards, and start the box cooling source to cool it down. The temperature change rate is Not more than 1C/min (not more than the average value within 5 minutes). The final value of the box temperature should be adjusted to such a value that the temperature of the test point on the surface of the test sample reaches the correction value 7 of the above-mentioned stable temperature. . This temperature should be maintained during the entire condition test and tested according to d to f in 10.7.1.1. The temperature conditions of the two stages when testing according to method B are shown in Figure 2. Test sample plate temperature.
Uncooled peripheral temperature T
Test sample temperature T:
Uncooled peripheral temperature T:
Test sample temperature T,
Adjusted test temperature term = test phase temperature
GB 2423.1—89
In the first stage, the test sample is loaded, the circulating airflow in the test chamber is disconnected, and the test sample temperature is not cooled. The test is carried out under the conditions in the chamber.
In the second stage, the test sample is loaded. The ventilation device of the test chamber is turned on to connect the airflow, but the cooling source is not turned on. The test is carried out under the conditions of the test chamber. T1-△T\, should be small. In the third stage, the test sample is loaded, the air flow in the test chamber is turned on and cooled, and the specified ambient test temperature is monitored.
Figure 1 Test Ad method A, diagram of the temperature state of the test with forced air circulation In the first stage, the test sample is loaded and tested under the test room conditions with forced air circulation. The test sample is gradually adjusted to 7
Indoor ambient temperature 7
Test sample temperature T:
Test chamber temperature
Provide the test progress T:
Test sample temperature quantity.
Phase 2: The test sample is loaded and tested in a test chamber with forced air circulation. The temperature of the test sample is controlled (△T, which must be small). Figure 2 Test Ad method B, diagram of the test sample temperature when the temperature rise of the test sample with forced air circulation is greater than 25°C 10.7.2 Test samples with artificial cooling
If the test sample is cooled, the relevant standards should specify the characteristics of the coolant supplied to the test sample. If the coolant is air, it should not be contaminated by oil and should be dry enough to avoid the influence of moisture. 10.7.2.1 Cooling system and test chamber (room)\Separate* test samples with artificial cooling The cooling system of this type of test sample is either self-installed or the coolant is supplied externally, and the coolant circulation flow pipe is separated from the test chamber (room).
GB2423.1-89
This type of test sample can be tested according to the method without forced air circulation in Article 10.7.1.1 of this standard, and method A in Article 10.7.1.2 with forced air circulation can be used as an alternative method.
10.7.2.2 Test sample with artificial cooling where the cooling system and the test chamber are "not separated" 8: The test sample is taken from the outside of the test chamber (room) with fresh cooling air, and the sample flows into the test chamber (room) after the cooling test. This type of test sample can be tested according to Article 10.7.1 of this standard.b. The test specimen is taken from the test chamber (room) with cooling air and returned to the test chamber (room) after completing its cooling task. Such test specimens may be tested according to the method of 10.7.1.1 of this standard without forced air circulation, and the method of 10.7.1.2 with forced air circulation is used as an alternative method. However, the air entering the test specimen shall be monitored and the temperature of the air shall be within the specified limits.
10.8 Intermediate testing
The relevant standards may require that loads and/or measurements be applied while the test specimen is still in the test chamber (room) during or at the end of the conditioning test. If such measurements are required, the test specimen shall be subjected to intermediate testing in accordance with the provisions of 8.8. 10.9 Recovery
Perform the procedure specified in Article 8.9 of this standard
10.10 Final test
Perform the final test in accordance with the provisions of Article 8.10 of this standard. 10.11 When the relevant standard adopts this test method, specific provisions should be given for the applicable items of Article 7.2. Example:
Weekly temperature
GB 2423.1-89
Appendix A
Ambient temperature correction calculation chart
(Supplement)
Constant touch current
The test sample surface has deteriorated,
Question: A product that dissipates a certain power has a surface temperature of 70℃ in free air at 20℃. What is its surface temperature when it dissipates the same power in free air at 40℃? Answer: From T. Draw a straight line from the +20°C point on the T2 ruler to the +70°C point on the T2 ruler, and note its intersection with the pivot axis. Draw a straight line from the -40°C point on the T2 ruler through this intersection on the pivot axis. Read the new intersection with the T2 ruler, which is +23°C. This is the required surface temperature T2.
Additional Notes:
This standard was proposed and coordinated by the National Technical Committee for Environmental Conditions and Environmental Testing of Electrical and Electronic Products. This standard was drafted by the Guangzhou Electric Science Research Institute. The main drafters of this standard are Xu Guobao, Li Zhiqing, Zhu Yaochang, Ma Xiucui, and Yuan Shuncai.
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