Analysis of the temperature rising of 500 kV composite insulators

Abstract The heating defects of composite insulators pose a serious threat to the safe and stable operation of power transmission lines. A case of heating in composite insulators on a 500 kV transmission line was investigated, where two types of heating insulators on the line underwent visual inspection, infrared testing, dissection examination, hydrophobicity tests, permeability tests, water diffusion tests, and sealing tests. The defects and causes of heating in the composite insulators were analyzed. The results showed that both types of heating insulators exhibited poor adhesion between the core rod and sheath, and the water diffusion leakage current exceeded the standard value. This defect is the cause of the core rod deterioration and heating in the insulators. Operational maintenance recommendations were made based on these findings.