The high on-state loss of cryogenic solid-state circuit breakers makes it a heavy burden in realizing the High-Temperature Superconducting (HTS) electrical system. Due to the ability to work in cryogenic circumstances and extremely low on-state loss, the LN ₂ switch shows excellent application potential in the HTS electrical system. However, the effect of the magnetic fields on the arcing process in the LN ₂ is still unclear. This paper aims to obtain the effect of the magnetic fields on the arcing process in the LN ₂ . Neodymium (NdFeB) magnets are used to provide the changeable magnetic fields. DC interruptions ranging from 200 A to 1800 A are conducted under 0 mT, 20 mT, and 50 mT respectively. A high-speed camera is also employed to capture the arcing process. Arcing in the LN ₂ under magnetic fields is characterized as the arc dwell period and arc voltage rapidly increasing period, which is quite similar to that in the air, but more frequent arc restrikes are observed. The magnetic fields strengthen the convective arc cooling by mixing the arc with LN ₂ and the vaporized N ₂ , contributing to the sharp increase in arc voltage. Thus, the magnetic fields significantly increase the arc voltage and its raising rate. 630 V/1038 A is successfully interrupted under the magnetic field of 50 mT in the LN ₂ . The successfully interrupted current increases by 8 times when magnetic fields are applied.

中文翻译：

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高温超导电力系统中磁场对液氮直流中断的影响


低温固态断路器的高通态损耗使其成为实现高温超导（HTS）电力系统的沉重负担。由于能够在低温环境下工作以及极低的通态损耗，LN ₂开关在高温超导电气系统中显示出优异的应用潜力。然而，磁场对 LN ₂中电弧过程的影响仍不清楚。本文旨在获得磁场对LN ₂中电弧过程的影响。钕 (NdFeB) 磁铁用于提供可变磁场。分别在 0 mT、20 mT 和 50 mT 下进行 200 A 至 1800 A 的直流中断。还使用高速摄像机来捕捉电弧过程。磁场作用下LN ₂中的电弧特征为电弧停留期和电弧电压快速增加期，与空气中的电弧非常相似，但观察到更频繁的电弧重燃。磁场通过将电弧与LN ₂和汽化的N ₂混合来加强对流电弧冷却，从而导致电弧电压急剧增加。因此，磁场显着增加了电弧电压及其升高速率。 630V/1038A在LN ₂ 50mT磁场下成功开断。当施加磁场时，成功中断的电流增加了 8 倍。