Determination of six infrared defects

According to “infrared diagnostic application specification for energized equipment DL/T 664-2016” there are six kinds of infrared defect determination methods:

1. surface temperature judgment method

It is mainly applicable to current-heated and electromagnetic effect-heated equipment. According to the measured surface temperature value of the equipment, against Appendix G, combined with the environmental and climatic conditions at the time of detection and the actual current (load) of the equipment, the maximum current (load) that may occur in normal operation and the rated current (load) of the equipment, etc. to analyze and judge.

2. Relative temperature difference judgment method

Mainly applicable to current-heat type equipment, especially for the detection of current (load) is small, and in accordance with the 1 failed to determine the type of defective equipment current-heat type equipment, in the absence of conflict with the provisions of Appendix G under the premise of the use of the relative temperature difference judgment method, can improve the accuracy of the type of defective equipment to determine the reduction of equipment defects when the operation of the current (load) is smaller than the rate of omission of judgment.

3. Image feature judgment method

Mainly applies to voltage-heat type equipment. According to the normal state of similar equipment and the abnormal state of the thermal image, to determine whether the equipment is normal should try to exclude all kinds of interfering factors on the image of the impact, if necessary, combined with the results of electrical testing or chemical analysis, comprehensive judgment.

4. Comparison of similar judgment method

According to the same type of equipment between the corresponding part of the surface temperature difference between the comparative analysis and judgment. For voltage-heat type equipment, should be combined with 3 judgment: for current-heat type equipment, should be in accordance with the first 1 judgment, such as failing to determine the type of defects in the equipment, and then in accordance with the 2 judgment, and finally in accordance with the 4 judgment. Archives (or historical) thermal image is also used as a comparative judgment.

5. Comprehensive analysis and judgment method

Mainly applicable to the comprehensive heating type of equipment. For oil-immersed casing, current transformers and other integrated heating equipment, when the defect is caused by two or more factors, should be based on the operating current, heat parts and nature, combined with 1 ~ 4 lines of comprehensive analysis and judgment. For the magnetic field and magnetic leakage caused by overheating, can be based on the current to heat type equipment to judge the evidence.

6. Real-time analysis and judgment method

In a period of time to let the infrared camera continuous detection / monitoring of a device under test, observation, recording equipment temperature changes with the load, time and other factors, and real-time analysis and judgment. Mostly used for non-conventional large load test or operation, with defects in the operation of equipment tracking and analysis and judgment.