Numerical Analysis On Electromagnetic Field And Thermal Field Of12kV Disc Vacuum Interrupter

Because of its excellent insulation and arc-extinguishing performance, it is widelyused in medium voltage switchgear.AS the SF6gas is kind of greenhouse gas andrestricted to its use, so it provides the opportunity for high-voltage class development ofthe vacuum switch. Meanwhile, compared with SF6,using vacuum as arc-extinguishingmedium can effectively reduce the volume of vacuum switch and its cost. In general,vacuum switch will towards high-voltage, large-current and miniaturization. As for theminiaturization of vacuum switch, this paper proposes a new type of vacuum interrupter:disc vacuum interrupter of three phrases. Vacuum interrupter which is the core componentof vacuum switch, its performance determines whether the vacuum could open the circuitor not. So the designing of vacuum interrupter is a key link in the process of developmentof vacuum switch. In this paper,3D electromagnetic field and thermal field of12kV discvacuum interrupter are conducted so that the results could provide reference and guidancefor the development of the vacuum switch.Based on the basic experience Formula, tables and figures, size parameters of the12kV vacuum interrupter are acquired and the3D model is also built. Then the finiteelement numerical calculation method on the whole domain of the three-dimensionalelectric field calculation and analysis is used. in order to find the position and time of theelectrical field, a cycle of three-phase voltage source excitation is discreted. The phasevalues could be calculated after the time of the max electric field is acquired. Then the measures are taken to reduce the max electrical field based on the analysis of the reasons ofthe appearance of the max electrical field. According to measures taken to reduce the maxelectrical field, the3d model is modified and the static electrical field analysis is calculated.When compared to max electrical filed of the former model, the max electrical field oflatter model confirmed the feasibility of the above measures.In order to improve the breaking performance of vacuum interrupter, this paperproposes a modified longitudinal magnetic poles of the contactor to adapt to thecharacteristics of the structure of the breaker. According to maxwell’s equations, the finiteelement method (fem) is adopted to solve the vacuum interrupter of3d axial magneticfield(AMF) of eddy current. AMFs of the arc center plane and contact center plane areacquired respectively when current value is zero and at its peak. Then the interference ofthree-phase magnetic field to control the shape of arc is discussed. Measures are also takento eliminate the interference of magnetic field and the effectiveness is confirmed.Finally, the finite element method of the three-dimensional thermal field is calculated.The thermal field of the single phase at its rate working current and short line current iscalculated respectively. And cooling fin is brought to reduce the temperature and theresults meet the request of the standard.