Research On Concave Shape Axial Magnetic Field Contact Structure For Asymmetric Vacuum Interrupter

With the advantages of stable performance, safety and environmental protection, vacuumcircuit breaker has been widely used in power system. The core component of the vacuumcircuit breaker is the contact system of the vacuum interrupter axial magnetic field, whose roleis to produce the necessary axial magnetic field between the vacuum interrupter fractureswhen it is breaking current. The research results show that the best distribution of the axialmagnetic field imposed at the vacuum interrupter fracture is lower at the central area andhigher at the marginal area, which can attract the vacuum arc gathering at the central area tomarginal area. Then the arc column plasma will be prevented to shrink, the vacuum arc willexist at diffusion form, all of which will be beneficial to arc blow-out.A contact structure of asymmetric concave shape axial magnetic field was proposed inthis paper. The axial magnetic field between the contact gap is produced by the coil structureat the static contact side, while the moving contact doesn’t have any coil structure. Thiscontact structure can reduce the quality of the moving contact and simplify the structure of themoving contact. The finite element method has been adopted to make numerical simulation toone half and one third turn coil with iron core, and the residual magnetic field, delay time andconductor resistance of the contact system has been compared with that in the symmetricalconcave shape axial magnetic field contact system. The results show that the magnetic fieldintensity distribution of the axial magnetic field produced by this contact system is lower at thecentral area and higher at the marginal area, which appears as a concave shape. This axialmagnetic field with a concave shape could restrain the vacuum arc from contraction availably,which can enhance the current breaking ability of the vacuum circuit breaker. This system alsogets the lower residual magnetic field, the shorter delay time and the smaller conductorresistances.In addition, this paper also analyzed the influence caused by the changes of theparameters of coil structure in the contact structure of asymmetric concave shape axialmagnetic field to the axial magnetic field in vacuum interrupter and other characteristics,which has provided a basis to the structure design of this type contact structure of vacuuminterrupter.