Thermal Aging Characteristics of Vehicle-Mounted Cable Terminal Stress Control Tube and Its Influence on Insulation Performance
In order to determine the thermal aging characteristics of the vehicle-mounted cable terminal stress control tube and its influence on the insulation performance of cable terminal under thermal aging conditions,firstly,the macro-dielectric characteristics and micro-aging law of vehicle-mounted cable terminal stress control tube were determined through experimental research.Secondly,based on the analysis of the electrical conductivity,polarization,and loss characteristics of the stress tube material under thermal aging,the dielectric characteristic curves under different aging periods were obtained.Finally,a finite element model of the electric field of the vehicle-mounted cable terminal was established by considering the aging characteristics of the stress control tube,and the electric field distribution of the cable terminal of the stress control tube was calculated based on the dielectric parameters under thermal aging.The results show that the electrical conductivity increases most significantly at 140℃and reaches the maximum value of 1.1×10-10 S/m at a field intensity of 50 kV/m.The relative dielectric constant reaches the minimum value of 14.00 at high temperature(140℃)for 20 days.In addition,trap hindrances such as folding and breaking of polymer long chain are enhanced during pyrolysis reaction,and the dielectric loss increases.In terms of functional group characteristics and microstructure of the stress control tube,thermal aging results in pyrolytic polymerization of olefin polymers in stress control tube materials,forming chemical stereoscopic defects.In addition,the cracking of polymer spherulites and the formation of inorganic oxidation products on the surface of the stress control tube sample are intensified,and the physical and chemical properties of the sample surface are changed.Simulation results show that under thermal aging conditions,the electric field distortion area inside the cable terminal presents a trend of expanding,creeps along the stress control tube towards the terminal high voltage,and finally stabilizes at the junction of the main insulation layer of ethylene propylene rubber(EPR)and stress control tube.
vehicle-mounted cable terminalstress control tubethermal aging characteristicsmolecular functional groupinsulation performanceelectric field distribution
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