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摘要
Mechanical weakness is one of the most important factors causing the fault of a three-post insulator in the GIL, and a common failure location is the epoxy-insert interface of the insulator. In this paper, three-post insulators in a 550 kV GIL with no defect, a debonded defect and an air gap in the epoxy-insert interface are employed as samples, respectively. An adhesion simulation model and a decohesion simulation model of the interface are established. Failure mechanism of the insulators under radial loads is studied by the numerical simulation and the experimental measurement. The experiment results illustrate that the fracture of the insulators under radial loads occurs in the semi-conductive adhesive layer and conforms to the brittle fracture. The adhesion simulation model is suitable for interface simulation before the fracture, and the decohesion simulation model is suitable for interface simulation in fracture process. Compared with the defectless insulator, fracture strength of the insulator with a 1 mm thickness debonded defect decreases sharply by 71.3%, while that of the insulator with an air gap of 1 mm diameter and 5 mm height decreases slightly by 4.9%. Combined with the simulation results, the fracture process of three-post insulators under radial loads could be inferred as follows: a crack appears as soon as the stress of the epoxy around the maximum curvature of the epoxy-insert interface reaches its tensile failure strength, after that the crack quickly extends along the inner of the peripheral epoxy and the bottom of the interface until finally fracture. In other words, the failure of three-post insulators under radial loads depends on the tensile strength of the epoxy around the maximum curvature of the interface.
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单位南方电网技术研究中心
