自能SF6断路器冷气流开断压力特性

Pressure characteristic of cold gas flow interruption for a self-blast SF_6 circuit breaker

为了解决自能式SF6断路器在开断容性小电流时由于电弧能量较小、喷口堵塞效应不明显而出现开断困难的问题,以自能式SF6断路器为研究对象,根据场域数值模拟对冷气流开断下压力特性进行分析.采用柱坐标系下二维N-S方程描述气流参数变化,建立轴对称数学模型.利用有限体积法,结合实测触头分闸速度特性曲线进行冷气流开断气流场模拟.在喷口附近不同区域设置压力监测点,定量分析监测点处压力特性.研究表明,喷口上游压力变化直接影响断路器开断性能,长喷口结构对于灭弧室内压力下降有明显抑制作用.

The nozzle arc choke is used for establishing the higher pressure in upstream nozzle for a self-blast SF6 circuit breaker. The energy produced by the arc can be quenched by the gas flow for achieving interruption. However, for the capacitive small current interruption, the arc energy is relatively lower, the arc choke effect is not obvious, and the interruption becomes difficult. Thus, the field analysis of the pressure characteristic of the cold gas interruption for a self-blast SF6 circuit breaker was carried out. The 2-dimensional N-S equations in cylindrical coordinates were applied for describing the variation of gas flow parameters and establishing the axial symmetric mathematics model. Using the finite volume method and combing the measured velocity curve, the pressure characteristic at different points near the nozzle was quantitatively analyzed. It is shown that the interrupting capability of self-blast SF6 circuit breaker is influenced directly by the pressure variation in upstream nozzle area, and the pressure in the chamber can be effectively controlled by the nozzle structure.