Cause analysis on fracture of a 500 kV composite insulator

In order to study the cause of wire falling accident caused by fracture of 500 kV composite insulator in the no-fly zone of a province， various inspections and tests were carried out on the accident insulator string according to the current standard. The results of comprehensive detection and analysis and on-site fault investigation show that due to the defects in the interface between the glass fiber and the silicone rubber sheath of the composite insulator rod， the rod of the insulator is aged after many years of operation. In addition， due to the comprehensive influence of the operating environment， the internal fibrosis and overall structural degeneration of the rod are aggravated， which eventually causes the insulator to break down and cause the wire to fall off. Finally， in order to avoid the recurrence of such accidents and ensure the safe and stable operation of the power grid， the operation and maintenance strategy of composite insulators is given for the lines under the jurisdiction of the UAV no-fly zone and weak signal zone.