Study On The Influence Of Multi-factor Aging On The Interface Characteristics Of Composite Insulated Cross-arm

The composite insulated cross arm has gradually replaced the traditional steel cross arm in the erection of transmission lines due to its high strength,light weight,corrosion resistance,durability and electrical insulation performance.Compared with composite insulators,composite insulation crossarms are subjected to more bending stresses perpendicular to the axial direction during operation,as well as wind deflection,wire dancing,etc.,which may cause irregular stress vibration and oscillation of the crossarm for a long time.In the case of composite cross-arm stress fatigue aging.In addition,the temperature difference between day and night or seasonal changes will also cause the composite insulation crossarm to withstand high and low temperature cycles.These may lead to aging phenomena such as gap delamination at the composite cross-arm interface,and reduce the service life of the composite insulation cross arm.It is well known that there are two kinds of macroscopic interfaces between the silicone rubber sheath and the mandrel and the inner filling of the mandrel and the mandrel.The interface problem between the silicone rubber sheath and the mandrel has been extensively studied at home and abroad.In view of this,this paper intends to simulate the operating conditions of composite insulated cross-arms,multi-factor artificial accelerated aging test of mechanical stress,cyclic thermal stress and electric field stress on composite cross-arm insulation samples,and then by means of leakage current,dielectric loss and other macroscopic Characteristic test and microscopic characteristic testing techniques such as scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR)were carried out to study the variation of the interfacial properties of composite insulated cross-member core rod(FRP)and polyurethane under multiple factors.The research results are expected to provide some reference for the evaluation and detection of the interface characteristics of composite insulated cross arm.Firstly,the sample provided by the manufacturer was cut to facilitate the test,and combined with the actual working condition of the composite insulated cross arm,the force and the electric field were calculated,and the test temperature was determined according to relevant industry standards.A multi-factor aging test plan for composite insulated cross-arm specimens was designed based on the determined test parameters.Five different control experiments were designed to analyze the effects of different aging factors on the interfacial properties of composite insulated cross-arm samples.At the same time,a multi-factor aging test platform for composite insulated cross-arm specimens was built according to the determined test parameters,and multiple sets of different control tests were set up to analyze the influence of differentaging factors on the interface characteristics of composite insulated cross-arm samples.The aging samples were tested in both macroscopic and microscopic aspects:macroscopically,the aging samples were measured for the peeling work,the leakage current was measured after the water diffusion test,and the dielectric loss was measured;The subsequent samples were scanned by electron microscopy and Fourier transform infrared spectroscopy,and the degree of damage at the interface of the sample and the change of chemical bonds were observed.Based on the above research results of experimental parameters,based on the composite insulator aging platform construction standard,a multi-factor artificial aging test platform for composite insulated cross-arm specimens for the research of this subject was built.According to the composite insulation cross-arm interface characteristic test project,the sample was determined.The aging test scheme of composite insulation cross arm under mechanical stress,cyclic thermal stress and electric field stress is designed.Through the aging of the composite insulated cross-arm sample,the peeling work test,water diffusion test,leakage current measurement and dielectric loss test were carried out to study the change of FRP and polyurethane interface under multi-factor aging.The SEM and FTIR tests were carried out.Microscopic observation of the microstructure and chemical bond changes of the interface between FRP and polyurethane.The following results are obtained: as the aging time increases,the lower the stripping work,the greater the leakage current and dielectric loss,the more aging factors,the greater the dielectric loss,and the effect of the force on the leakage current and stripping work of the aging interface.Significantly;SEM results show that as the aging time increases,the separation of the sample interface is more obvious,and the alternating force is more serious than the constant force damage.The FTIR test results show that the chemical bond between the two materials at the interface increases with the aging time.The change is very obvious,and a large number of chemical bonds are broken.The analysis results show that the multi-factor aging has a more obvious influence on the interface characteristics,and the mechanical aging has more serious damage to the interface.Measurement of dielectric loss and FTIR detection are more sensitive to the characteristics of the interface.