In order to investigate the influence of nozzle ablation to arc,a 2-D axisymmetric magneto-hydro-dynamics arc model is developed to simulate the arc behavior during the whole interruption process in a puffer-type high voltage circuit breaker,considering the nozzle ablating and the mixing process of Polytetrafluoroethylene(PTFE) vapor with SF6.The results show that the arc radius firstly increases and then decreases as arc current varies according to its sinusoida waveform.At 3.5 ms after arc initiation the nozzle ablation starts,and 2.5 ms later the current nearly reaches its peak value and nozzle ablation develops intensely.Meanwhile the nozzle is blocked by arc at this time and consequently the vapor concentration in nozzle reaches the highest.Then while the current decreasing and open distance increaseing the vapor concentration gradually decreases.Before current zero the extinction peak of arc voltage occurs.It indicates that the PTFE vapor enhances pressure rise in arc quenching chamber and strengthens the arc blocking effect on nozzle;the arc radius is wider and arc temperature is lower when nozzle ablation is considered.
单向阀的运动特性对自能膨胀式高压SF6断路器的仿真计算结果准确度具有直接影响。为此,提出了一种耦合了阀片运动的自能膨胀式高压SF6断路器磁流体动力学模型,对2种典型开断条件下(短路电流有效值为36k A和40 k A,燃弧时间15.3 ms)的燃弧情况进行了研究;对比分析了不同电流下灭弧室内的温度分布、气压分布、喷口烧蚀质量以及单向阀的运动特性。结果表明,40 k A条件下灭弧室内的整体温度和气压高于36 k A条件下;40 k A条件下的单向阀比36 k A条件下的单向阀提前0.8 ms动作,喷口烧蚀质量增加了0.35 g。
