The fault of power circuit breaker (PCB) can lead very serious problems, especially in high voltage–power grid. The structure of contacts may be composed of main contacts and arc contacts, and this structure can avoid ablation of main contacts efficiently. It is necessary to study the eroded state of the arc contacts and the dynamic contact resistance of arc contacts to estimate the operating state of the PCB. The wear of contacts contains arc ablation and mechanical wear through the characteristics of contacts. The arc ablation is caused by the high temperature of the arc and the mechanical wear is caused by the mechanical friction of static and movable contacts. Some experiments have been done under different size of contacts and different current through them. The results show that the mechanical wear increases, sometimes heavier, with the increase of the size of fixed contacts and the decrease of the size of movable ones because the force between fixed and movable contacts becomes larger. The results also show that the ablation of arc contacts increases with the increase of current, especially when the current is up to 20 kA. With the high temperature of arc reaching the hardness point of copper, the arc ablation and mechanical erosion are increasing obviously since the contacts become soft and easy to wear. Another result of the study shows it is important to choose the material of contacts and the force between movable and fixed contacts. The harder and less resistance the material of contacts, the better the operating situation. To monitor the operating situation of the breaker, the dynamic contact resistance was measured 25 times. As a result, the dynamic contact resistance is sensitive to the current and increasing with the increase of continuous experiment time because of the increasing of metal ions. Furthermore, if the SF6 in the PCB is changes, the dynamic contact resistance would be changed. The dynamic contact resistance in this experiment varies substantially within the range of 80–250 μΩ at the current of 20 kA.

中文翻译：

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大电流断路器电弧触头烧蚀及动态触头电阻研究

电源断路器（PCB）的故障会导致非常严重的问题，尤其是在高压电网中。触头结构可以由主触头和电弧触头组成，这种结构可以有效避免主触头烧蚀。需要研究电弧触头的侵蚀状态和电弧触头的动态接触电阻来估计PCB的工作状态。触头的磨损通过触头的特性包括电弧烧蚀和机械磨损。电弧烧蚀是由电弧的高温引起的，机械磨损是由静触头和动触头的机械摩擦引起的。一些实验已经在不同尺寸的触点和不同的电流通过它们的情况下进行。结果表明，机械磨损增加，有时更重，随着固定触头尺寸的增加和动触头尺寸的减小，因为定触头和动触头之间的力变大。结果还表明，电弧触点的烧蚀随着电流的增加而增加，特别是当电流达到20 kA时。随着电弧的高温达到铜的硬度点，触头变软易磨损，电弧烧蚀和机械侵蚀明显增加。研究的另一个结果表明，选择触头材料以及动触头和固定触头之间的力很重要。触点材料越硬，电阻越小，操作情况越好。为了监测断路器的运行情况，动态接触电阻测量了 25 次。因此，由于金属离子的增加，动态接触电阻对电流敏感，并随着连续实验时间的增加而增加。此外，如果PCB中的SF6发生变化，动态接触电阻也会发生变化。本实验中的动态接触电阻在 20 kA 的电流下在 80-250 μΩ 的范围内变化很大。