The core rod decay of composite insulator can lead to serious accidents such as line drops, a power frequency withstand voltage test is conducted on the short samples of 1 000 kV decay-like and deteriorated composite insulators, and the heating characteristics are analyzed through infrared thermography. By disassembling and inspecting the abnormal heating parts of composite insulators, analyzing their physical and chemical properties, and conducting finite element simulation calculations, the causes of abnormal heating of decay-like composite insulators are identified. The research results show that severely decay-like composite insulators exhibit significant abnormal heating phenomena, with a maximum temperature rise can reach tens of K. Compared with the normal core rod, the insulation resistance in the decayed area of the core rod significantly decreases, and the dielectric loss tangent increases significantly, the value can reach around 30% in areas with severe decay, and the leakage current value also increases significantly, and the degree of heating of the core rod is closely related to its degree of decay, with higher temperature rise in the severely decayed area.
