Test and Analysis of Broken String Composite Insulator

This paper analyzes the cause of the failure of a composite insulator, and conducts a post-mortem inspection and test analysis on the fault insulator and non-fault insulator in the same phase. A continuous carbonized discharge channel has been formed at the low-voltage end, which is characterized by penetrating internal breakdown. The leakage current in the water diffusion test of the faulty insulator exceeded the standard, indicating that the bonding performance of the mandrel sheath has decreased significantly, which in turn caused an air gap at the mandrel-sheath interface, which caused the mandrel to be susceptible to moisture and internal discharge ablation. Degradation and carbonation of epoxy resin, etc.