Rearch On Electric Field Distortion And Tracking Of Roof Insulator With Mosit Contamination On High-Speed Air Enrieonment

With the technical advantages of fast,safety,high punctuality,high capacity and light pollution,high-speed railway occupies an important position in transportation,and has developed rapidly over the past 10 years.As the key HV equipment of tractive power supply system,the roof insulator not only isolates train body from pantogragh,generatrix etc,but also plays a supporting role,of which malfunction could result in EMU temporary outage.By EMU roof compact layout,insulator strcture height is limited 0.5m.Although the roof insulator is made by expoy,with high hydrophobicity and hardness,discharge probably occurs in rain wether,destroying insulator and damaging to the safe operation of the EMU.The rain and fog makes pollution moist.After repeatedly drying and damping,the hydrophobicity of insulator declines,electric field distortion is enhanced,corona discharge casuses the arc along insulator,and when the surface temperature exceeds the resistance temperature,expoy carbonization forms tracking,which probably makes insulator loss of insulation and leads to operational failure.Hence,the electric field distortion of insulator under mosit pollution is analyzed and tracking under arc is researched,which have provided theoretical foundation to improve the reliability of roof insulator operation.High speed airflow by the EMU operation results in an uneven air pressure distribution around the insulator.Affected by air drag force,the motion parameters of raindrops change.Therefore,according to the model of droplets touching the wall,an effective criterion is constructed that raindrops collide insulators and absorb on their surface.The model of insulator wind tunnel is established based on Fluent.The discrete phase is selected for numerical simulation of rainfall.The UDF fuction is used to achieve the effective criterion.The distribution characteristics of rainfall on insulators are analyzed,and the influence of rainfall intensity,inlet wind speed and incoming flow angle about the rainfall accumulation is researched.According to Quasi-static field theory and Ansoft software,the FEM of the insulators with the clean state,water droplets and mosit contamination is established.The influence of the external electric field direction,hydrophobicity and the degree of water droplets fusion on the electric field distortion along surface with droples is analyzed.Based on the polynomial regression,the maximum electric field of water droplets,external electric field direction and contact angle is found.The electric field distribution of clean and stained insulators is compared.The difference on the electric field distortion caused by the contamination at different area of insulator is studied.Although expoy insulators possess the excellent electrical and mechanical performance,the tracking is also found along the insulator on the routine maintenance overhaul.Hence,in order to find weak points that the roof insulators are vulnerable to form tracking with EMU high speed operation.Based on ANSYS,a three-dimensional nonlinear transient electro and thermal coupling model is established that roof insulator discharges along surface.The temperature distribution on insulator with discharge is analyzed.The relationship between the degree of tracking and time is found.And the influence of air pressure distribution and inlet wind speed on the degree of tracking is researched.