National standards of the People's Republic of China
Test method for forced air cooling and heat characteristics of electronic equipment GB/T 12992-91
Measuring methods of thermal characteristic for forced air cooling of electronic equipment
Subject content and scope of application
1.1 subject content
This standard provides methods for measuring temperature, flow rate and pressure of forced air cooling of electronic equipment under normal atmospheric pressure.
1.2 scope of application
This standard is applicable to the surface temperature of electronic components, ambient temperature and chassis (cabinet) surface of forced air cooling electronic equipment under normal atmospheric conditions
Measurement of temperature, measurement of air velocity (or flow rate) in ventilation system, and measurement of static and dynamic pressure of airflow in air duct.
2 reference standards
GB 1236 test method for aerodynamic performance of ventilators
GB 2421 general rules for basic environmental testing of electrical and electronic products
GB 2624 flow measurement throttling device part I throttling parts are standard orifice plate and Angle connection for Angle connection, flange connection
Pressure standard nozzle
GB 2903 cu - cu thermocouple wire and indexing table
GB 4993 ni-cr-cu thermocouple wire and indexing table
3. Terms and symbols
3.1 the term
5. 1.1 temperature stabilization
When the equipment is in working condition and the surface temperature of heating components in the equipment changes no more than 2℃ per hour, the temperature is said to be stable.
3.1.2 external environment temperature
When the equipment reaches temperature stability, the weighted average of air temperature is 80 mm away from the geometric center of the main surface of the equipment.
3.1.5 cabinet surface temperature
When the equipment reaches temperature stability, the average temperature of the test point on the main surface of the equipment.
3.1.4 surface temperature of parts
The temperature of the hot spot on the component package surface.
3.1.5 critical temperature parts
Components whose surface temperature may be close to the maximum allowable operating temperature.
A -- cross-sectional area of air duct, m2;
D- duct diameter (or equivalent diameter), m;
D.-- diameter of throat of the collector, diameter of hole plate opening m;
Approved by the state administration of technical supervision on August 19, 1991
Test technical conditions
4.1 the atmospheric conditions of the test environment shall conform to the provisions of the normal test atmospheric conditions in GB 2421.
4.2 the temperature test shall be carried out under the working condition of the maximum heat consumption of the equipment.
4.5 when testing the surface temperature of electrified components and the air temperature around them, the temperature sensor (thermocouple) shall be ensured to have sufficient electrical insulation
4.4 when testing the surface temperature of components and the surrounding air temperature at places with strong alternating electromagnetic fields, the thermocouple should be shielded.
4.5 the laying of the thermocouple shall not have a significant impact on the temperature field of the tested equipment or components.
4.6 the test of pressure and flow rate (or flow rate) should be carried out when the ventilation system is in normal operation.
4.7 the pressure and flow rate (or flow rate) test sensor should not produce significant influence on the air flow field.
5. Temperature test method
5.1 temperature test content
The following items should be included in the temperature test:
A.Equipment external environment temperature;
B.Case (cabinet) surface temperature;
C.Surface temperature of components (including temperature critical components);
D.Cooling air inlet temperature and outlet temperature;
E.The temperature of key parts inside the equipment.
5.2 temperature testing equipment
5.2.1 temperature sensor
Thermocouple made of standard copper, constantan or ni-chromium, with wire diameter less than or equal to 0
Comply with GB 2903 and GB 4993.
5.2.2 test instruments
Temperature measuring instrument with test speed of not less than two test points per second, accuracy of 0.5 grade or resolution of 10 uy.
5.2.5 reference end
6. Stress test method
6.1 stress test contents
Stress tests should include the following:
A.Static and dynamic pressure at the entrance of the ventilation system;
B.Static and dynamic pressure at the outlet of the ventilation system;
C.The static pressure and dynamic pressure of the key parts with large resistance in the air passage.
6.2 pressure test equipment
6.2.1 pressure probe
The static pressure and dynamic pressure of air flow were measured by l-type static pressure probe and dynamic pressure tube respectively.The dynamic pressure tube shall comply with clause 3.9.1 in GB 1236
The pressure gauge for testing the pressure shall be selected according to the measured pressure according to table 2.
6.3 stress test method.
6.3.1 pressure test point position
188.8.131.52 for electronic equipment with ventilation ducts, the static pressure test point shall be 80 ~ from the ventilator and the cooling air inlet of the chassis (cabinet) respectively
At 100 mm, four static pressure holes and joints are evenly distributed along the circumference on the wall of the same test section.
184.108.40.206 the position and points of dynamic pressure test points in the circular air duct should conform to the provisions in figure 2 and table 3.Rectangular duct dynamic pressure test position and
Points should be evenly arranged in the same cross section of three to six test points, the arithmetic mean.