Study On Electrical Branch Monitoring System Of Polymer Insulating Material

In recent years,XLPE cable is widely used in cable transmission system because of its good electrical characteristics.The formation of electrical tree will cause the aging and destruction of XLPE cable,which will cause failures and potential safety hazards for power transmission system.Therefore,in order to analyze the growth characteristics and related mechanism of electrical tree in XLPE cable insulation,and to find a way to inhibit or prevent electrical tree initiation,this paper designs an electrical insulation monitoring system for polymer insulation material.Based on the principle of image acquisition,real-time observation of CCD,initiating device of electrical tree,and connection scheme of breakdown protection circuit,the electrical insulation monitoring system of polymer insulation material is designed based on PC.The growth process of electrical branches under different external conditions was observed with XLPE as a sample,and the effective performance of the system was tested.The test results show that the electrical tree monitoring system designed in this paper,meet in different external conditions,can be real-time monitoring of electrical tree dynamic growth process and record the image to the PC side,the optical module can be observed to ensure a clear image of the tree,and the introduction of supporting circuit breakdown protection,also to prevent the sample breakdown resulting in equipment damage.The growth characteristics of electrical branches in XLPE were analyzed according to the experimental results.Analysis shows that with the growth of the voltage,initial discharge time of the electrical tree growth time increased,decreased,the fractal dimension increases,the shape of the dendritic tufts into;with the electrode spacing increases,increased the discharge starting time and the growth time of the electrical tree,the fractal dimension is reduced,the shape of the dendrimer into rattan mixed tree shape;analyzes the relationship between fractal dimension and morphology of electrical trees,found that the fractal dimension is between 1-2,the more close to 1,its shape is close to the branch,the more close to 2,its shape is close to the jungle.The fractal dimension <1.45,its shape is close to sparse dendritic and fractal dimension is between 1.45-1.62,its shape is close to densely branched or double structure,the fractal dimension >1.62,its shape is close to the jungle;analyzes the distribution laws,electricaltree results show that when the frequency is fixed at 50 Hz,the electrode spacing is 1mm 2mm,when the voltage below 12 k V when its shape is dendritic,voltage above 13 k V when its forms were jungle shape,high voltage,it is difficult to form a pure vine like.The morphology of the 2mm electrode has two structures,and the critical voltage of the dendritic and the jungle increases when the electrode spacing increases.