冲击气流作用下灭弧防雷间隙截断电弧的机理

Mechanism of Arc-Extinguishing Lightning Protection Gap Under Stress of Impactive Airflow

为了提高输电线路防雷高效性,以普通并联间隙为基础提出一种基于冲击气流作用的灭弧防雷间隙。通过分析灭弧防雷间隙和绝缘子配合时的伏秒特性,研究了其截断电弧机制。建立链式电弧模型,并对电弧元进行受力分析,推导出电弧元各速度分量控制方程,得出其数值与电弧元长度无关,与冲击气流速度有关,且气流速度越大电弧运动越快越利于熄灭电弧。运用Ansys10.0软件对流体进行气流场仿真,利用高速摄像机拍摄电弧的变化过程,通过数字示波器记录电弧电压波形,仿真结果与试验结果表明:2.6 ms时冲击气流速度最大且稳定的作用于电弧,试验得出气流熄灭电弧的时间4.5 ms,没有发生重燃,一致说明该装置能快速截断电弧。

In order to improve the transmission line lightning protection efficiency, arc-extinguishing lightning protection gap which is based on the impactive airflow is put forward on the basis of ordinary paraUel gap.The mechanism of arc-extinguishing gap truncating arc is studied through analyzing voltage- time characteristic of arc-extinguishing lightning protection gap equipped with insulator strings. A chain arc model and force analysis of arc element is established and the velocity components control equations of arc element are deduced. It is concluded that its numerical has nothing to do with the length of arc element, but associated with impactive airflow speed, and the faster the airflow speed, the greater the arc speed, the more conducive to extinguishing arc. Using AnsyslO.O fluid modeling software, the fluid flow field simulation is carried out; using high-speed cameras screen, the development process of arc is recorded and the arc voltage waveforms are also recorded by a digital oscilloscope.The simulation results and experimental results show that the high-speed airflow velocity is the largest in 2.6ms and acts on arc steadily, experiments reach a conclusion that airflow extinguish arc＇s time is 4.5ms, and without rekindle, results consistently show that the device can quickly extinguish arc.