Study On The Permanent Magnetic Actuator For 12KV Energy Economizing Vacuum Circuit Breaker

Vacuum Circuit Breaker (VCB) is the primary product of media voltage electric switch equipment. Its reliability and intelligent levels have far-reaching influence on the stability and the extent of automatization for electric power system. Permanent Magnetic Actuator (PMA) as one kind of the actuator of VCB, has the advantages of less part number, higher reliability, and more controllable parameters, and overshadows the traditional actuators for Circuit Breaker (CB). Based on the detail analysis of PMA of VCB in existence, a novel PMA of VCB, which is monostable, has two coils, is proposed.In order to validate the feasibility of proposed PMA, the 2D model of this PMA is established and analyzed, firstly. The breaking and closing course of this PMA is detailed analyzed, when the permanent magnet acts by oneself and the permanent magnet acts with the main coil. The feasibility of proposed PMA is proved by the analysis results.In order to exactly analyze the characteristics of attract and reverse forces in different conditions, the 3D model of proposed PMA is established and analyzed. The holding force of permanent magnet in closing position and the characteristics of attract and reverse forces in the breaking and closing course are detailed analyzed.With the application range of VCB assembled PMA is more and more abroad, the requirement to PMA are more and more strict. The PMA is able to break the VCB by itself when the fault of low-voltage happened. In order to realize the function, the detect coil of voltage is joined in this PMA. Different functions can be realized using the two coils of proposed PMA finish. In which, the combination of the main coil and the permanent magnet is to perform the interrupting operation. And the auxiliary coil is to detect the voltage. So the proposed PMA can detect the variety of voltage in main circuit at any moment. When the fault of low-voltage happened, it can automatically finish the breaking operation. The parameters of coils are detailed designed, and the above functions can be correctly finished.The work point of permanent magnet will be changed with the varieties of outside magnetic field. The work characteristic of permanent magnet is analyzed in different outside magnetic field.The positions and dimensions of every parts of proposed PMA are designed based on the analysis results. Based on the dimensions, the prototype is manufactured and assembled to the VCB. The type-testing to the VCB is finished. From the results of type-testing, the feasibility and validity of the proposed PMA has been verified.