Performance Evaluation Of High Density Pressboard Based On Physical And Dielectric Properties

The insulation system of large converter transformer is mainly made up of oil paper insulation.Its insulation is affected by external factors such as moisture,temperature and electric field intensity,which will lead to aging and malfunction of oil paper insulation system.Therefore,the performance evaluation of high density pressboard is of great significance to the design,selection and operation of the insulation system of the converter transformer.According to the performance evaluation of high density oil immersed board,there are many problems such as single dimension,less index data,insufficient consideration of running environment variables,and lack of comprehensive horizontal comparison among various electrical pressboard manufacturers.This paper mainly selects the insulation board products of 5 representative electrical board manufacturers.And then select the physicochemical properties and dielectric properties of the two evaluation dimensions.Physical properties include five indicators,including apparent density,water extraction conductivity,oil absorption rate,polymerization degree and expansion ratio.Dielectric properties include four indicators,such as relative dielectric constant,volume/surface resistivity,dielectric loss and so on.In this paper,a laboratory test method for pressboard samples is adopted,including statistical products,design and test plan,test platform and data.First,the single performance of each manufacturer's insulation board is investigated under each index,then the weight of the index is analyzed,and the comprehensive performance of five manufacturers' insulation board products is sorted out by using the scoring mechanism.The conclusion is fair and persuasive,and has important reference value for the operation,design and selection of transformer oil-impregnated pressboard insulation system.The main contents of this paper are as follows:(1)Introduce the background of this paper and the overseas and domestic research status.It is found that there are few studies on the comprehensive performance evaluation of the oil-impregnated pressboard made by different manufacturers of converter transformer,and the performance evaluation is of great practical significance for the design and manufacture of power equipment.(2)According to the performance evaluation requirements of oil-impregnated pressboard,the evaluation method is divided into physicochemical properties and dielectric properties of two dimensions and nine indicators.The physical and chemical characteristics include apparent density,conductivity of water extract,oil absorption rate,degree of polymerization,and expansion rate.The dielectric properties include the relative dielectric constant,the volume resistivity,the surface resistivity,and the dielectric loss.According to the measured data of nine evaluation indexes,the basis of the evaluation method is formed,and various experiments are carried out.(3)Introduce the physicochemical properties,dielectric properties of the test.basis and method and the experimental platform is set up.Explain the process and requirements of the test.Through the test data processing,the paperboard performance of 5 manufacturers under each evaluation dimension and each evaluation index is obtained.(4)On the basis of physicochemical properties and dielectric properties of the test data,calculate the standard deviation of the data and determine the weight of each evaluation.The physical and dielectric properties are graded respectively.Finally,add the scores of the two dimensions.We can get the sorting of the performance of the insulation board of 5 manufacturers...