Study of the interference factors and defect temperature field characteristics of infrared testing for composite insulators

Abstract
A study was conducted on the interference factors during on-site inspection of infrared testing for composite insulators. The temperature curve of the composite insulator core rod in service status was detected online using infrared equipment. The fluctuation characteristics of the temperature curve of normal composite insulators and their error range on temperature difference were analyzed in detail. Furthermore, the effects of multi angle testing, occlusion, image clarity, testing distance, and lens focal length on the core rod temperature curve were further studied, and corresponding countermeasures were proposed. The experimental results indicate that the fluctuation characteristics of the temperature curve are closely related to environmental factors and testing equipment, and the testing accuracy can be improved by optimizing the testing methods and equipment parameters. In addition, for the measured infrared data, after removing high-frequency fluctuation parameters using preprocessing methods, defective insulators can be selected based on the temperature gradient and the two-dimensional graph of the umbrella skirt unit temperature difference. This work establishes a practical framework for standardizing infrared inspections of critical grid infrastructure.