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Experimental Study On Thermal Aging And Partial Defects Of Vehicle Ethylene Propylene Rubber Cable

Posted on:2019-04-06Degree:MasterType:Thesis
Country:ChinaCandidate:S B ZhuFull Text:PDF
GTID:2322330563454949Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
The vehicular high voltage cable is one of the important power equipment for electric locomotive and high speed train,which undertakes the power transmission work of the vehicle.However,due to the complex and changeable regional environment,the operation environment of vehicle cable is very bad,so it is often faced with the joint action of electric,thermal,mechanical and humid,leading to the great test of its insulation performance.At the same time during the process of installing cable terminal and accessories,due to the impact of technology and uncontrollable factors,there will be local defects.These defects contribute to the production and increase of partial discharge,resulting in persistent damage to insulation and seriously effects on the safety of cable and train.According to the aging principle of cable insulation,the paper designs accelerated aging test,prepares the cable sample that can be used in the laboratory oven accelerated thermal aging test and dielectric spectrum test,builts the accelerated aging test platform and constant temperature system,tests the dielectric parameters and mechanical parameters and analyses dielectric properties and degradation state of thermal aging condition.Test results show that the complex permittivity curves are increased with the decrease of the frequency;at high frequency(1Hz~1000Hz)changes of real and imaginary parts are small,but at the low frequency(0.01Hz~1Hz)the imaginary part values of different aging time are significantly different.The real part curve of the complex permittivity will slightly rise with the increase of aging time;at the determined aging temperature,the dielectric spectrum of the samples show an increasing trend with the increase of aging time;at different aging temperature,dielectric spectrum of samples rise with the increase of temperature,and the values of low frequency are more sensitive to aging time and temperature.There is a positive correlation between aging time and tan? integral value,and the effect of aging time on tan delta integral value is accelerated with the increase of thermal aging temperature.The effect on cable insulation of aging time and aging temperature is in accordance with the time temperature equivalent principle.Under the laboratory condition,the change of test voltage has little effect on the dielectric spectrum test of cable sample,while the cable is affected by other degradation factors,the low frequency test value of dielectric spectrum will slightly change.Influence of test temperature on imaginary part of complex permittivity can be decomposed into the comprehensive effect of horizontal axis(along with the increase of temperature,the imaginary part of complex permittivity shifts in high frequency direction)and longitudinal axis(for the same test frequency,imaginary part of complex permittivity increases with the elevation of temperature).Based on operation failure of vehicle cable,the paper prepares cable samples,which contain three kinds of typical defect including mark of the knife,graphite electrode and air gap,for partial discharge experiments,the partial discharge spectrum and the related eigenvalue are provided,the test proves that the PD of cables with defects are severer than that of cables without defects.The partial discharge pattern and characteristic of different detects are different.The increase and development of the partial discharge of the defective cable will inevitably lead to the reduction of the insulation performance of the vehicle cable,which will affect the operation of the cable.
Keywords/Search Tags:Vehicle cable, Ethylene propylene rubber, Dielectric spectrum, Local defect, Partial discharge
PDF Full Text Request
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