Study On The Performance Deterioration Mechanism And Aging Characteristics Of Silicone Oil Paper Insulation For Train Traction Transformer

As the core component of high-speed train,vehicle-mounted traction transformer undertakes the important mission of providing stable power for high-speed train.Oil-paper insulation is an important guarantee of insulation capacity of vehicle-mounted traction transformer,and its performance is a key factor determining whether the emu can run safely and stably.Silicon insulation oil and Nomex insulation paper,as new insulation materials for vehicle-mounted traction transformers,are of great theoretical significance and engineering value to study their aging characteristics and performance degradation mechanism under the action of thermal stress.First of all,this article on the basis of the on-board traction transformer operation condition and environment,silicon oil and Nomex paper insulation insulation as the research object,design under the temperature gradient of many cycle accelerated thermal aging test,the regular testing its aging characteristic parameters,studied the various characteristic parameters changing with the temperature and aging test,found that silicon oil and Nomex paper insulation insulation breakdown voltage,tensile strength and the degree of polymerization in the process of aging gradually reduce;When the silicon insulation oil and Nomex insulation paper age together,the moisture content decreases first and then increases.The main products of dissolved gas in silicon insulation oil are CH₄,H₂ and CO,while the main products of dissolved gas in Nomex insulation paper oil are CO,CO₂ and H₂.Therefore,the aging degree of Nomex insulation paper in silicone paper insulation system can be predicted by detecting the content of dissolved gas CO₂ in oil.Secondly,based on the molecular dynamics simulation to silicon insulating oil monomer molecules polydimethylsiloxane（PDMS）and Nomex paper insulation monomer molecules between poly benzene formyl m-phenylene diamine（PMIA）as the research object,analyzes the PDMS and PMIA at different temperature cracking path and product formation mechanism,two monomer molecules is studied under the different water mass fraction of pyrolysis rule and mechanism of the influence of moisture,found that the increase of reaction temperature and reaction time will promote the PDMS and PMIA cracking;CH₄ and H₂ are the main characteristic products of PDMS cracking under thermal stress.With the increase of reaction temperature,the number of small molecule silicon compounds increased and the number of large molecule silicon compounds decreased.Water promotes the pyrolysis of PDMS.PDMS will decompose before water,and then the decomposition of water provides H and O atoms for the reaction system,accelerating the generation of each characteristic product.The initial bond breaking position of PMIA molecule is mainly the amide bond between benzene rings,followed by the c-c bond connected with carbonyl group.NH₃ and CO are the main characteristic products of PMIA pyrolysis.With the increase of reaction temperature,the number of small molecules containing carbon compounds increased,while that of large molecules containing carbon compounds decreased.Water can promote the hydrolysis of PMIA,and water in the environment can accelerate the hydrolysis of PMIA.Finally,the experiment and simulation for comprehensive analysis,found that with the increase of aging time and aging temperature rise,silicon oil and Nomex paper insulation insulation characteristics of gas product content change trend in the process of experiment and simulation,the correctness of the simulation is verified,and realized with silicone oil paper insulation aging characteristics and performance degradation mechanism research.