Study on Unstable Temperature Rise of Slightly Heating Composite Insulator Based on Infrared Detection

In this paper, the phenomenon of unstable temperature rise (UTR) in infrared detection of composite insulators is investigated. Firstly, according to the infrared detection data, the influences of environmental humidity and commissioning year on the temperature rise (TR) of composite insulators are analyzed. Secondly, four pieces of composite insulators with abnormal heating on the same line are selected for visual inspection and macroscopic detection. Meanwhile, the infrared temperature measurements are carried out both under AC and DC voltage, and the mechanism of slight heating is studied. The statistical data and experimental results show that the UTR phenomenon of composite insulator is related to the ambient humidity and the observation angle of infrared thermal imager. The TR under high humidity is much higher than that under low humidity, and the observation angle will affect the infrared temperature measurement results. In addition, with the increase of the service life of composite insulators, the silicone rubber material will deteriorate. Then, with the immersion of polar molecules such as water, the polarization loss of the material increases, resulting in abnormal temperature rise (ATR) of composite insulators when it is in a high humidity environment. Besides, it is recommended that multi-angle photography should be taken to avoid measurement error.

I. Introduction

Composite insulators are widely used in overhead lines all over the world, owing to their advantages of small size, light weight, excellent weather resistance, electrical and mechanical properties, as in [1]–[3]. With the increase of service life, composite insulators comprised of the organic materials will inevitably deteriorate, resulting in the degradation of material performance. Furthermore, it will lead to internal breakdown and broken string fault of insulators, as in [4]–[8]. Meanwhile, it will be accompanied by abnormal heating, which has great potential hazards for the stable operation and safety of power system. Therefore, it is vital to study the abnormal heat generation of insulators.