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How to use infrared thermometers to diagnose equipment problems
- 2019-06-29-

Infrared thermometers are used to diagnose the core problems of equipment faults by infrared thermometers , and it is required to accurately obtain the temperature spread of the equipment under test or the temperature value and temperature rise of the fault-related points. This temperature information is not only the basis for judging whether the equipment is faulty, but also an objective basis for judging the attributes, location, and severity of the fault. Therefore, the calculation and reasonable correction of the temperature of the relevant parts of the tested equipment are the key links to improve the accuracy of the external temperature of the testing equipment. However, when the equipment infrared detection is performed on-site, because the detection conditions and environmental influences change, the same equipment may get different results due to different detection conditions. Therefore, in order to improve the accuracy of the infrared detection, it is necessary to adopt corresponding countermeasures and methods or select good detection conditions during the on-site detection process or the analysis and processing of the detection results, or make reasonable corrections to the detection field results.

Electrical equipment faults are generally caused by current effects (conductive circuit problems-heating power is proportional to the square of the load current value), and voltage effects caused by heating effects (insulation medium problems-heating power and the square of the operating voltage Proportional). Therefore, the working voltage and load current of the device will directly affect the role of infrared detection and fault diagnosis. The increase of leakage current can cause uneven voltage of some high-voltage equipment. If the load is not loaded or the load is very low, it will make the device's fault fever not significant, and even if there is a serious fault, it will not be exposed due to the characteristic thermal anomaly. Only when the device is operated under extra voltage and the load is greater, the heat and temperature rise will be more severe, and the characteristic heat abnormality of the fault point will be more exposed.

In this way, in order to obtain a reliable detection effect when performing infrared detection, it should be ensured that the equipment operates under extra voltage and full load as much as possible. Even if continuous full load operation cannot be achieved, an operation plan should be prepared so that Before and during the test, the device can be operated at full load for a period of time, so that the faulty part of the device has a satisfactory heating time, and ensure that its external expression reaches a stable temperature rise. When the electrical equipment is diagnosed with infrared, the fault identification code is usually based on the temperature rise of the equipment at the extra current. Therefore, when the actual operating current is less than the extra current during the detection, the temperature rise of the equipment fault point measured in the field should be converted into additional Temperature rise of current.

The device's external infrared thermometer measures the temperature of the infrared radiation of electrical equipment to obtain the temperature information of the equipment. And under the condition that the infrared diagnostic equipment receives the same infrared radiation power from the policy, different detection results will be obtained due to the different appearance emissivity of the policy. That is, the lower the emissivity at the same radiant power, the higher the temperature will appear. Because the object's external emissivity is mainly determined by the nature of the data and the external conditions (such as external oxidation status, coating information, roughness and contamination status, etc.).

Therefore, in order to accurately measure the temperature of electrical equipment using infrared temperature measuring instruments, it is necessary to know the emissivity value of the tested policy, and enter this value as an important parameter for calculating the temperature and input it into the computer or adjust the ε correction value of the infrared measuring instrument in order to The measured temperature output value is corrected for the emissivity. Two countermeasures to eliminate the influence of the emissivity on the test results: When using an infrared thermometer to measure, you need to correct the emission, find out the emissivity value of the appearance of the component of the device under test, perform the emissivity correction, and then obtain a reliable temperature measurement Achievements, improve the reliability of detection; for faulty frequent equipment parts of infrared detection, in order to make the detection results have good comparability, the method of applying appropriate paint can be used to increase and stabilize the emissivity value in order to obtain the measured The actual temperature of the exterior of the device.