Study On The Space Charge Characteristics Of Polyethylene Materials At Different Temperatures

With the progress of science and technology and the advancement of socioeconomics,the development of electric energy has also become an crucial link in economic development.The transmission of electric energy is even more inseparable from power cables.Polyethylene insulated power cables have low dielectric loss and simple installation,so they are extensive adpot.Under the action of an external electric field,the space charge accumulated in the material will produce electric field distortion,accelerate aging,shorten the life of the insulating material,and even cause failure.Therefore,in order to study the distribution and transport mechanism of carriers in polyethylene materials at different temperatures,this paper will focus on the relationship between space charge and conduction current in polyethylene materials at different temperatures.This paper studies the space charge distribution and movement of four different polyethylene materials at different temperatures.The electroacoustic pulse method(PEA method)and laser excited pressure wave method(LIPP method)were used to analyze low-density polyethylene.The space charge tests of polyethylene,imported polyethylene and anhydrous maleic acid grafted low-density polyethylene were carried out at 30℃,50℃,70℃ and 80℃ respectively,and the two test methods and test results were compared.The change trend of the space charge distribution of the two methods is basically the same,and the space charge movement of the LIPP method is more obvious in the insulating medium.Experimental results show that space charges of the same polarity are more likely to accumulate near the anode at room temperature,and the rise in temperature promotes the dissociation of impurities,resulting in more accumulation of space charges of different polarities near the electrode.Among them,the low-density polyethylene material grafted with anhydrous maleic acid has an excellent space charge suppression effect,but the temperature rise suppression effect is weakened.The imported polyethylene shows its excellent ability to suppress space charge at high temperatures.The domestically-made cross-linked polyethylene material shows more space charge accumulation at various temperatures.The LIPP method measuring device using the combination of space charge and conduction current measures space charge and conduction current simultaneously at 30℃,50℃,70℃ and 80℃.The experimental results show that in the Omic conduction area,the increase in temperature will only change the magnitude of the conduction current.The conductive properties of the conductive area remain unchanged.In the current region where the space charge is limited,as the temperature rises,the vector injection volume increases and the field threshold threshold intensity continues to decrease over the years.In the meantime,as the strength of the electric field increases,the number of space charge astrict has changed exceeding,and the conduction current value under the corresponding electric field intensity also has a sharp change,which shows that the accumulation of space charge has a direct impact on it.The conduction current of the insulating material also changes.We employ the PEA and the LIPP to measure the space charge of four separate materials at 30℃,50℃,70℃ and 80℃,and researched the impact of temperature.The contrastion and probe into the affinit and distinction between the two provides a new testing method for studying the space charge characteristics of insulating materials.At the same time,the LIPP method is used to test the material with a test device that combines space charge and conduction current.Therefore,the relationship between the space charge distribution and the conduction current of the polyethylene material is more intuitive and accurate.