An Ultrasonic Guided Waves-Based Assessing Method for Decay-Like Degrees of Composite Insulator Core Rods

Abstract

In recent years, the decay-like fracture of composite insulator core rods is encountered frequently, which has seriously affected the reliability of transmission lines. However, there is a lack of assessment method to quantify the degrees of composite insulator core rod degradation. In this article, a method for assessing the degree of composite insulator’s degradation based on ultrasonic guided waves was proposed. The study focused on core rods with different decay-like fracture degrees in composite insulators obtained from the field. Simulations and tests of ultrasonic guided waves were conducted to assess the decay-like degrees, and the physicochemical properties of composite insulators at different stages of decay-like development were tested to verify the assessment results from a microscopic perspective. The results show that the 35 kHz T(0, 1) and 55 kHz L(0, 1) modes are suitable for detection, and the peak-to-peak values of the ultrasonic guided wave packet received at a certain distance decrease with the increase of the decay-like degree. With the progression of decay-like aging, the dielectric constant, the dielectric loss tangent, and the carbon content in the core rod increase significantly. On the other hand, the oxygen and silicon contents show the opposite trend. Infrared spectral results can effectively distinguish new factory samples and samples with decay-like fracture deterioration. However, it shows limited differentiation capability for composite insulators at various stages of decay-like aging. The research provided a reference for assessing the decay-like degree of composite insulator core rods.