应用有限元方法分析塑壳断路器磁脱扣器的动作特性

以计算得到的载流导体电流密度分布为激励,分析磁脱扣器的静态磁场,计算磁转矩和磁链随气隙和电流变化的静态数据网格,联立磁脱扣器的电路瞬态方程和可动部件的机械运动方程,考虑脱扣力的作用,运用4阶龙格-库塔法求解脱扣器动作特性.实验证明,脱扣器动作时间计算值的误差不超过10%.分析了磁脱扣器的保护特性与反力弹簧特性和初始工作气隙的关系,结果表明,改变反力弹簧的初始长度相对于改变弹簧刚度和初始工作气隙更容易实现对塑壳断路器脱扣电流的线性调节.

Action Characteristics Analysis of Magnetic Release for Molded Case Circuit Breaker with 3-D Finite Element Method

A method is proposed to investigate the dynamic characteristics of a magnetic release in molded case circuit breaker. Based on the static field assumption, two grids of the magnetic torque and flux linkage are calculated with the variation of the current and air gap firstly. Considering the influence of tripping force, coupled with circuit equation and mechanism motion equation, the dynamic characteristics may be obtained with Runge-Kutta 4 method. And the influence of the reaction spring on the operation characteristic is analyzed. Experiments demonstrate that the difference of the protection characteristic curve between experiment and simulation is below 10%, and it is easier to adjust the initial length of the reaction spring to meet the requirement of changing tripping current linearly, relative to adjusting the stiffness of the reaction spring and the initial working air-gap.