Research on Non-destructive Testing Method for Aging of Sheds of Composite Insulators

Abstract

As an important part of external insulation of transmission and distribution lines and substation equipment, silicone rubber insulators are generally used because of their strong anti-pollution flashover ability, excellent hydrophobicity, and lightweight. It is one of the effective means to obtain the aging degree of sheds quickly and accurately to prevent operation accidents. From the micro and macro perspectives, firstly, this paper uses the traditional scanning electron microscopy and dielectric loss factor test to classify the aging degree of 11 high-voltage side sheds samples of silicone rubber insulators running on-site for 0~11 years. According to the different experimental principles, the aging degree of each experimental method is divided into four grades. Then, the detection method based on terahertz time-domain spectroscopy is proposed to realize a nondestructive evaluation of the aging grades of sheds of silicone rubber insulators. Finally, through comparison, it can be found that the THz absorption coefficient spectra can find the characteristic quantity of classification of aging levels of silicone rubber materials: The aging levels of the silicone rubber samples increase, and the absorption peak at 1.32 THz in the absorption spectra show a downward trend. According to the characteristic quantity, 11 samples can also be divided into four aging grades, and the results are consistent with the previous experiments.