12kV真空断路器半双稳态永磁机构的设计

应用于真空断路器的永磁操动机构一般分为双稳态和单稳态永磁机构。对于单稳态永磁机构,通过调整分闸弹簧在分闸位的预拉力,可以实现对分闸特性的调节。增大预拉力可以缩短分闸时间,降低分闸弹跳,但预拉力过大会导致合闸状态时的保持合力减小,可能造成合闸的不可靠,也会对合闸动态特性造成不利影响,如合闸时间增加等。本文提出了应用于12kV真空断路器的半双稳态永磁机构的设计方法,该机构在分闸状态由较小的永磁保持力和弹簧力共同实现分闸保持。分闸位保持力大有助于抑制分闸弹跳,同时永磁保持力在动铁芯离开分闸位置后迅速减小,对合闸保持以及合闸动态特性几乎没有不利影响。利用Ansoft Maxwell软件建立永磁机构模型,进行静态和动态的仿真。根据设计结果制作实际样机,对其进行测试,实验结果验证了设计与仿真的正确性。

Design of half bistable permanent magnetic actuator used in 12 kV vacuum circuit breaker

The permanent magnetic actuator used in vacuum circuit breaker is generally divided into bistable state and single steady state permanent magnetic actuator. For the single steady state permanent magnetic actuator, it can achieve the regulation of break-brake characteristics by adjusting the pretension of the break-brake spring in the open position. Increasing the pretension can shorten the opening time and reduce the switch-off bounce. But if the pretension is too large, it will lead to the decrease of the resultant force in the closing state, and this may cause the unreliability of closing operation. The pretension will be also unfavourable to the dynamic characteristics of the clos-ing process, such as the increase of the closing time,etc. This paper presents the design method of a half bistable permanent magnetic actuator used in 12kV vacuum circuit breaker, and the actuator maintains in the opening posi-tion by a small permanent magnetic retaining force and a spring force. Large retaining force in the open position helps to restrain the switch-off bounce. At the same time, the permanent magnetic retaining force decreases rapidly after the moving iron core leaves the open position, and it almost has no adverse effects on the closing retaining force and the dynamic characteristics of the closing process. Ansoft Maxwell software is used to establish the model of permanent magnetic actuator to carry out the static and dynamic simulation. An actual prototype has been made according to the results of the design, and it has been tested. The results have verified the correctness of the design and the simulation.