Mechanisms of dielectric breakdown of ljquid coolants under quench condition and estimation of withstand voltage

淬火条件下液体冷却剂的介电击穿机理及耐压估算

• 批准号: 08455136
• 负责人: HARA Masanori
• 金额: $ 4.8万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455136/
• 关键词: Superconducting Magnet; Quench; Insulation Design; Liquid Coolant; Thermal Bubble; Gradient force; Area Effect; Pool-boiling He-cooled; 超伝動コイル; 極低温; 部分放電; 密閉ボイド; 電界放出; 放電電荷量

In this study, establishment of electrical insulation technique and development of insulation trust of a superconducting magnet were aimed at. Boiling phenomena of liquid nitrogen and helium used for coolant of the magnet under high electric field was investigated. Moreover, mechanism of breakdown of those liquid coolant and characteristics of withstand voltage were discussed. Obtained results were summarized as follows.1.Electrical insulation design of pool-boiling He-cooled superconducting coilsInsulation design procedure was proposed and applied to a small SMES.It was found that the main parameters determining insulation space were delay time of quench protection switch, initial coil current, coil inductance, and conductor geometry and size.2.Bubble behavior in liquid coolant under quench conditionBubble behavior under high electric fields was studied theoretically and experimentally. The results showed that bubble motion was influenced mainly by an electrical gradient force acting on it. Then it is very important to pay attention to a setting of the gasp length in order to get a passage of the coolant under quench condition.3.Breakdown characteristics of LNi and LHe including a superfluid condition were investigated statistically.It was shown that the statistical characteristic of breakdown were well fitted to Weibull distribution based on weak-link theory and area effect was dominant rather than volume effect for size effect of electrodes to the breakdown characteristics.

在这项研究中，对超导磁体的电绝缘技术的建立和绝缘信任的发展均针对。研究了在高电场下用于磁铁冷却液的液氮和氦的沸腾现象。此外，讨论了这些液体冷却剂的分解机制和承受电压的特性。总结如下。1。提出了池沸腾的电池隔离设计，提出了他冷却的超导螺旋固定设计程序，并将其应用于小的中小型企业。发现确定绝缘空间的主要参数是延迟的时间延迟静置的电流，盘旋电流和电动尺寸的静电性行为。在理论上和实验上进行了研究。结果表明，气泡运动主要受到作用在其上的电梯度力的影响。那么，要注意在淬火条件下通过冷却剂的通过，这一点非常重要。3。LNI和LHE的损坏特征在统计上进行了研究。它表明，基于虚弱的链接理论和面积效应的特征效应效果效果，分解的统计特征非常适合基于Weibull分布，而构成了Weibull分布，而不是效应。

项目成果

生澤 宏彰: "極低温窒素ガス中及び熱気泡存在時の液体窒素中における部分放電特性" 電気学会放電研究会. 13-18 (1997)

Hiroaki Ikuzawa：“存在热气泡的低温氮气和液氮中的局部放电特性”IEEJ 放电研究组 (1997)。

M.Hara: "Insulation Design of Pool-boiling He-cooled Superconducting Coils" IEEE Trans.on DEI. 4・6. 792-799 (1997)

M.Hara：“池沸腾氦冷超导线圈的绝缘设计”IEEE Trans.on DEI 4・6（1997）。

M.Miyama: "Short Gap Breakdown Characterisitics of Helium Gas at Room Temperature under Equivalent Condition of Superconducting Coil Quenching" Trans.IEE of Japan. Vol.116-A,No.7. 628-634 (1996)

M.Miyama：“超导线圈淬火等效条件下室温下氦气的短间隙击穿特性”Trans.IEE，日本。

Z.C.Wang: "Bubble Behavior and Breakdown Characteristics in LHe under Simulating Quench Condition of S.C.Magnet" Trans.IEE of Japan. Vol.116-A,No.10. 873-880 (1996)

Z.C.Wang：“模拟S.C.Magnet淬火条件下LHe中的气泡行为和击穿特性”，Trans.IEE，日本。

原 雅則: "浸漬冷却超伝導コイルの絶縁設計法" 電気学会論文誌B. 116-B・7. 777-784 (1996)

Masanori Hara：“浸入式冷却超导线圈的绝缘设计方法”日本电气工程师学会会刊B.116-B・7777-784（1996）