SF_6自能膨胀式断路器喷口烧蚀的数学模型

Mathematical model of nozzle ablation in an SF_6 auto -expansion circuit breaker

喷口烧蚀是 SF6 自能膨胀式断路器研制中需要考虑的因素之一。通过分析电弧烧蚀喷口材料的机理 ,认为喷口烧蚀是在电弧能量的传导和辐射共同作用下引起的。将喷口烧蚀分为加热和烧蚀两个过程 ,并且 ,基于 Fourier导热微分方程分别建立了相应的数学模型。给出了开断过程中数值计算喷口烧蚀量的方法 ,计算并分析了烧蚀量与电弧电流及燃弧时间的关系。结果表明 :当开断电流大于一定值后 ,喷口烧蚀量增加较快 ;在电流峰值期间 ,喷口烧蚀量增加的最快。

Nozzle ablation by the arc is an important consideration in the design of SF 6 auto -expansion circuit breakers. The nozzle ablation is caused by conduction and radiation of the arc energy. A mathematical model of the nozzle ablation based on the Fourier heat conduction equation has been developed to numerically analyze the nozzle heating and the subsequent ablation. The model was used to relate the ablation to the arcing parameters such as current and time in the interruption. The results show that nozzle ablation is more rapid with larger short circuit currents and is the most rapid at the current peak of the arcing period.