Temperature rise test - electrical performance test
Date：2021-11-02 15:15:48 Views：5570
Temperature rise refers to the temperature of each component in electronic and electrical equipment above the environment. The current heat effect is generated after the conductor flows through. With the passage of time, the temperature of the conductor surface continues to rise until it is stable. The rated temperature rise of the motor refers to the maximum allowable temperature rise of the motor winding under the ambient temperature specified in the design (40 ℃), which depends on the insulation grade of the winding. The temperature rise depends on the heating and heat dissipation of the motor during operation. Often judge whether the heat dissipation of the motor is normal according to the temperature rise. In order to verify the service life, stability and other characteristics of electronic products, the temperature rise of its important components (IC chips, etc.) is usually tested. The tested equipment is operated at a specific temperature (t = 70 ℃) higher than its rated working temperature (t = 25 ℃). After stabilization, the temperature rise of its components higher than the ambient temperature is recorded to verify whether the design of the product is reasonable.
Temperature rise test is a routine test item in the type test of electrical products. The purpose of temperature rise test is to test the temperature change of electrical products and components, so as to determine whether the electrical products or components meet the requirements of the standard. With the rapid development of electrical equipment, temperature rise test is becoming more and more important for the safety of electrical equipment and components.
Temperature rise test method
According to different temperature measuring instruments, the temperature rise test methods can be divided into two categories: non-contact and contact.
1. Non contact measurement method
The non-contact measurement method can measure the external temperature of the measured object. The real temperature can be obtained only after the emissivity of the measured surface is corrected. Moreover, the measurement method is affected by the distance between the measured object and the instrument and other media such as water vapor, smoke and dust on the radiation channel, so the measurement accuracy is low. We often use spectral temperature measurement technology, holographic interference temperature measurement technology and three primary color temperature measurement technology based on CCD.
2. Contact measurement method
The temperature probe of contact thermometer generally includes thermocouple and thermal resistance:
The working principle of thermocouple is based on seeback effect. Two ends of conductors with different components are connected into a loop. If the temperatures of the two connecting ends are different, the physical phenomenon of thermal current will be generated in the loop. This phenomenon is used to measure the temperature.
The measurement principle of thermal resistance is to measure the temperature according to the characteristics that the resistance itself changes when the temperature changes.
In the contact test method, the temperature measuring element is in direct contact with the measured medium to directly measure the temperature of the measured object, so it is simple, reliable and high measurement accuracy.
Purpose of temperature rise test
Temperature rise test is one of the important tests for the safety performance of electronic and electrical products, which is used to evaluate the quality and electrical safety characteristics of electrical products. When electrical products are in normal use, due to the heating of some high current components, their own temperature rise is too high. Working under this state for a long time may reduce the performance of insulating materials, resulting in electric shock, scald or fire hazard of equipment. Temperature rise test is an important way to detect and avoid these dangers. The temperature rise test is aimed at the safety performance test of electrical connection equipment such as power line connector, socket, traction board, conversion plug, wiring terminal, connector and switch.
Equipment used for temperature rise test
Variable frequency power supply, AC / DC parameter measuring instrument, thermocouple wire (type K or j), UL glue and catalyst, data acquisition instrument, etc.
Conditions before temperature rise test
1. All equipment used must be calibrated in a one-year cycle. The sticky paper containing the final adjustment date and adjustment period must be adhered to each instrument.
2. Check the integrity of the prototype, and the parts, accessories and accessories shall be complete. 3. Prepare a representative prototype and place it at the ambient temperature of 23 ℃± 2 ℃ and humidity of 50% - 90% RH for 10h until the surface temperature of the prototype reaches equilibrium with the room temperature.
Testing and recording
1. According to standards or other requirements, the equipment or its parts shall run to the heat balance state under normal load conditions or the curve trend shall be obviously stable.
2. Maintain the rated load value operation, monitor the thermocouple feedback data at each temperature (temperature rise) measurement point, record the feedback value of the temperature (temperature rise) measurement point of the tested product, and measure and record the voltage, current, input power, output voltage, output current, output power, etc. of the tested product.
3. Stability of ambient temperature control: observe whether the ambient temperature curve is stable and whether the fluctuation range of the machine is within the effective range.
4. Whether the machine operates normally: in case of sound, spark, vibration, thermal protection or other abnormal conditions, immediately save the existing data, stop the test, check and analyze the causes and solve them as much as possible.
5. Check the curve and observe whether the change of temperature curve at each test point is reasonable. If there is any abnormality, immediately save the existing data, stop the test, check and analyze the cause and try to solve it.
6. After the test, people should walk around the test as little as possible, even if it is to check whether the data is normal, the walking speed should be slow, and the human body should be as far away from the tested machine as possible, so as not to affect the ambient temperature around the tested machine.
Temperature rise test standard
1. Connecting devices
GB/T 13140.1、GB/T34989、IEC 60998-1、IEC61984、EN 60998-1、EN 61984、AS/NZS 60998.1、UL 1977、UL 2238、UL 1059
2. Plug and socket
GB/T 2099.1、IEC 60884-1、AS/NZS 60884.1、DIN VDE 0620-1、BS 1363-1、UL 498、UL 1363
3. Appliance coupler
GB/T 17465.1、IEC 60320-1、EN 60320-1、AS/NZS 60320.1、UL 60320
4. Cord assembly and power cord
GB/T 13539.1、GB/T 31465、IEC 60269-1、EN 60269-1、ISO 8820、JASO D622、UL 248
6. Electrical equipment switch
IEC 60669-1、GB/T 16915.1、EN 60669-1、AS/NZS 60669.1
7. Information technology and communication equipment
GB 4943.1、IEC 60950-1、EN 60950-1、AS/NZS 60950.1、UL 60950
8. Audio and video equipment
GB 8898、IEC 60065、EN 60065、AS/NZS 60065、UL 60065
9. Household electrical equipment
GB 4706.1、IEC 60335-1、EN60335-1、AS/NZS60335. one
10. Lighting electrical equipment
GB 7000.1、EN 60598-1、EN 60598-1、IEC 60598-1、AS/NZS 60598.1