Research on the influence of moisture immersion on the electric field distribution of composite insulator with interface defects

Composite insulators have been widely used in power system. However, in practical application, they may have some faults, such as decay-like fracture and flashover of internal defects. In order to study the influence of the interface defects and moisture immersion on the electric field distribution characteristics, the 3D model of the 500kV composite insulator and its internal defects were established. The finite element analysis software COMSOL was used to calculate the electric field distribution by changing the length, span, thickness and tip curvature radius of the defect. The results show that the presence of air gaps and water gaps will significantly increase the local electric field strength. The maximum field strength is positively correlated with the span and thickness of the defects, and negatively correlated with the length. The tip curvature radius of the defects has no obvious effect on the air gap, but there is a point effect in the water gap.