Research On The New Type Electrode Structure With Axial Magnetic Field Of Vacuum Interrupters

For the excellent insulation and arc blowing out characteristics of vacuum are used sufficiently for vacuum circuit breakers which do not make pollution of environment, so middle voltage vacuum circuit breakers have been highly developed, and vacuum circuit breakers with high voltage and large capacity have become considerably interested in the world. Because vacuum interrupter is the heart of vacuum circuit breakers, The development of high performance vacuum interrupter has a strong theoretical and practical engineering value for the vacuum circuit breaker development.The constriction performance of vacuum electric arc at high current levels depends on the contact material and its operational principle. Axial magnetic field(AMF) contacts can prevent the vacuum electric arc from shrinking in the vacuum interrupters,and it can ensure the arc at diffuse arc state when at large breaking short-circuit current. Therefore, contact design have a more uniformity and stronger axial magnetic field(AMF) is the key skill to design vacuum interrupter.Base on the former contact model ,a new coil axial magnetic field electrode structure have designed in this paper. The main characteristic of this new model is that moving contact is simplified to enhance it breaking speed and mechanical intensity. So this stronger axial magnetic field(AMF) can make arc go out more easily, and the moving contact mass can be reduced. After that, breaking ability of vacuum interrupter can be improved. The improved structure also reduces the normal work of the Resistance loop carrier, which also increased the mechanical strength of the structure of the contact, greatly enhancing the vacuum interrupter breaking performance.Considered the arc influence, a 3-D electrode model of the new design was built up. 3D finite software ANSYS was used to analyze magnetic static field and eddy current field. After that ,two part time which at maximal current and zero current, the 2-D and 3-D distributing axial magnetic field(AMF) of the two contacts surface, and the center surface between two contacts are described. Delay time of the center surface between two contacts also be calculated. At last, according to the results , at equally current, value two contacts surface and center surface between the two contacts have more uniformity and stronger axial magnetic field (AMF) than the former one, and at zero time delay time of axial magnetic field (AMF)not be increased. So this new asymmetric contact design can enhance break limited current more possibility.