Insulation Properties And Controlling Methods Of Epoxy-based Dielectric With Nano-silica

The epoxy-based dielectric mainly refers to epoxy resin and dielectric material with epoxy resin as an important constituent component.This paper mainly includes three kinds of materials:epoxy resin,epoxy adhesive resin and mica tape.As a polymer insulating material,epoxy-based dielectrics are widely used in the power industry because of their good mechanical and electrical properties.For example,gas-insulated transmission lines?GIL?and gas-insulated switchgear?GIS?are important equipments for forming DC UHV transmission lines.Once a failure occurs,the chain reaction will cause the system to collapse,and the consequences are unimaginable.The column insulators and basin insulators used in GIL and GIS are made of epoxy resin.Another example is the adhesive resin,mica tape and impregnated epoxy resin which are widely used in the main insulation of high-voltage motors.The performance also directly determines whether the high-voltage motor can operate safely and stably.In recent years,with the wide application of frequency converters,the continuous improvement of high-voltage motors and the development of UHV DC transmission systems in China.People have higher requirements on the electrical properties of epoxy-based dielectrics under different working conditions.Therefore,it is particularly important to improve the insulation performance of the epoxy-based dielectric,so that the high-voltage motor,GIL,and GIS with the main components can be more stably and reliably operated.Numerous studies have confirmed that the introduction of appropriate nanoparticles in the polymer can effectively improve the properties of the insulating material.Nano-modified composite insulating materials have been initially completed in many high-voltage insulation fields,and the addition of nanoparticles to polymers to improve the performance of insulating materials has become a research hotspot.This is because when the particle size reaches the nanometer order,due to its small size,large specific surface area and high surface energy,it will exhibit many strange effects such as surface effect,small size effect,macroscopic quantum and tunneling effect.However,whether the nanocomposite dielectric has these advantages is related to the type,content,size,manner of the nano-added material and the interface formed between the additive material and the matrix material.In this paper,nano-SiO₂ was used to modify the epoxy-based dielectric nano-composite,and epoxy resin,adhesive resin and mica tape nanocomposite insulation samples with different nano-SiO₂ particle content were prepared.In order to determine the dispersibility of the nanoparticles in the epoxy material,samples with different mass fractions were observed using SEM.Analyze the structure of interface area.The characteristics of AC\DC breakdown strength,dielectric constant,dielectric loss factor,electrical conductivity,DSC,DMA and space charge of the sample at different temperatures were measured.The test results were analyzed based on Weibull distribution and trap distribution characteristics.The results show that the dielectric strength of nano-composite epoxy resin and nano-composite adhesive resin increased at first and then decreased with the increase of nano-particle content;the dielectric strength of three kinds of epoxy based materials decreased gradually with the increase of temperature;The doping of low content?0.5wt%?nano-SiO₂ had a positive effect on the dielectric properties of epoxy-based dielectrics under different temperature conditions;A large number of interfacial areas formed between epoxy matrix will change the space charge distribution,trap parameters,carrier mobility and internal electric field distribution of polymer materials,and then affect the dielectric properties of the materials.