Comparative Study On The Degradation Characteristics Of 10kV Heat Shrinkable And Cold Shrinkable Joints Under Partial Discharge

Local defects of cable joints easily lead to cable insulation breakdown accidents and have a great impact on their operating life.It is of significance to study the degradation characteristics of cable joints made of widely used heat-shrinkable and cold-shrinkable materials under partial discharge.The main work of the thesis includes three-dimensional simulation and analysis of electric field distribution of intermediate joints and terminals made of heat shrinkable and cold shrinkable materials through COMSOL Multiphysics software;construction of a power frequency pressurization platform,and pulse current method for heat shrinkable and cold shrinkable defective cables The connector is tested for partial discharge.By collecting the partial discharge amount under the voltage of 2U0 and 3U0,the PRPD spectrum is plotted and its characteristics are observed.The broken cable is dissected and compared with heat shrinkable and cold shrinkable materials.Traces of deterioration after breakdown of cable defect connectors.Through the above research,the paper obtained the following main results:the maximum field strength appears at the defect location when the heat shrinkable and cold shrinkable intermediate joints are defective.When radial defects,axial defects and moisture defects occur,the heat shrinkable intermediate joint is more prone to partial discharge;for terminal cables,the maximum field strength appears at the position of the defect when there is a defect.When the terminal defects have radial and axial defects,the field strength of the heat-shrinkable terminal is greater,and partial discharge is more likely to occur;when the moisture defect occurs,the field strength of the cold-shrinkable terminal is greater,and partial discharge is more likely to occur.The measured PDIV obtained by heat shrinkage and cold shrinkage is consistent with the distribution of the maximum field strength obtained by simulation.Through simulation and experimental analysis,it can be concluded that for prefabricated defective cable intermediate joints,axial defects have little effect on cable pressure resistance;radial defect heat-shrinkable materials have better pressure resistance;moisture-defective cold-shrink materials are better Some,but it is easy to produce conductive channels on the surface of the internal insulation layer,affecting the continuous operation of the cable.For the radial defects and moisture defects of the prefabricated cable terminal,the insulation performance of the cable made of cold-shrinkable tube is better;when the axial defect of the cable terminal occurs,the insulation performance of the cable made of heat-shrinkable tube is better.