Abstract
The interface is the weakness of composite insulators. As the interface bonding fails, the uniform distribution of electric field will be affected, which accelerates the aging of composite insulators and affects the safe operation of transmission lines. Because of the stress between the sheath and the rod, the air gap at the interface is generally less than 10 ţm and there is extrusion contact in some areas. Therefore, conventional nondestructive testing technology based on refraction and reflection principle cannot effectively identify the faulty insulators in the initial stage of bonding failure. Based on the constitutive model of the interface of composite insulators, the friction force of the interface after bonding failure introduces more nonlinearity in mechanical properties than hydrogen bond under well bonding condition. The numerical results show that under the influence of the nonlinear constitutive relation, the higher harmonic components in the spectrum will increase significantly. The experimental results of plate and insulator samples confirm the validity of numerical calculation. Based on the normalized nonlinearity coefficient, the interface state of composite insulators at the initial stage of bonding failure can be effectively identified.
Highlights
Advantaged by light quality and outstanding resistance of contamination flashover, etc., silicone rubber, glass fibre reinforced epoxy resin and other polymer are widely used in electrical equipment, such as sleeve, transformer, insulator and so on [1]–[4]
When composite insulators are put into operation, the uniform distribution of electric field is affected by interface defects
Under the action of discharge and hydrolysis, the interface defects caused by bonding failure will develop rapidly, which will lead to the corrosion of epoxy resin and the exposure of glass fibers
Summary
Advantaged by light quality and outstanding resistance of contamination flashover, etc., silicone rubber, glass fibre reinforced epoxy resin and other polymer are widely used in electrical equipment, such as sleeve, transformer, insulator and so on [1]–[4]. Influenced by the production process of composite insulators, bonding failure of sheath rod interface is a common hidden danger of composite insulators in transmission lines [5]. When composite insulators are put into operation, the uniform distribution of electric field is affected by interface defects. Under the action of discharge and hydrolysis, the interface defects caused by bonding failure will develop rapidly, which will lead to the corrosion of epoxy resin and the exposure of glass fibers. Existing research shows that this kind of fracture is closely related to the interface defect of composite insulators and it has led to great influence and
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