Electric Field Optimization And Analysis On Magnetic Field Of The 40.5kV Vacuum Interrupter

Comparing to the traditional SF6 circuit breakers, VCBs have several advantages, such as environment, performs safely and reliably. As the core component of VCB, the vacuum interrupter’s insulation and maximum overload current has a direct effect upon the properties of VCB. Recently, high voltage, miniaturization and large capacity has been the development trend of vacuum interrupter, the main content of the subject to improve and verified products which the type is TD-40.5/2500-31.5UA. It also calculated and analyzed the distribution of electric field and potential, discussion the various factors influencing the active area of contact surface, optimization the electric field in interrupter. The phase shift time was Cup-type of AMF was given.In this paper, the distribution of electric field and potential of 40.5kV vacuum interrupter was calculated by comparing two different main shields(X- and Y-) in finite element method. It was also analyzed the electric field curves of inner surface on main shield. The effect of different structure, radius and contact gap on active areas had been researched deeply. The results indicated that:(1) The electric field distribution was more uniform and the electric field intensity was less, when using X main shield,(2) the radius and the contact gap could affect the active areas, but the structure had no influence for active area.By using mathematical formula about the electric field distribution, minimum variance of the electric field intensity is what we want. By the first-order method in the optimization design module of ANSYS, this paper set optimal variables, objective function and loop steps. Minimum variance was 0.405, and it was lower than the previous one. Besides, the field distribution was more uniform and maximum field intensity falls markedly.The contact structures of VCB play an important role to the controlling on magnetic field distribution. This paper found a new 3D Cup-type AMF. The three-dimensional finite element analysis method was used. Calculated the 3D transient magnetic field when contacts disconnected completely; obtained the peak value and magnetic field distribution in two contact surfaces and center zone when current zero-crossing; drawn lag time curves of remaining field. The results indicated that:(1) for this cup shape and longitudinal magnetic contactor structure, the magnetic field distribution in two contact surfaces and center zone was uniform, when current peak;(2) remaining magnetic field was less in two contact surfaces and center zone when current zero-crossing;(3) the new contactor structure has little effect on eddy current and the lag time of remaining magnetic field was short.