Fabrication transport properties of QMG current limiting elements

Mitsuru Morita, H. Hirano, H. Hayashi, K. Terazono, K. Kajikawa, K. Funaki, T. Hamajima

研究成果: ジャーナルへの寄稿学術誌査読

6 被引用数 (Scopus)


A high durability design for QMG current limiting elements was developed by reinforcement using metal bypasses. Metal bypasses with high specific resistivity were bonded to both surfaces of QMG bulk superconductor using solder. I-shaped short QMG current limiting elements with cross-sections of 2.2×0.8 mm and an effective length of 20 mm were reinforced by I-shaped NiCr or SUS bypasses. Meander-shaped QMG with cross-sections of 2.2×0.8 mm and an effective length of 180 mm was reinforced by meander-shaped NiCr bypasses. These elements were molded by resin and GFRP. The external bypass was jointed to the element in parallel electrically. The current limiting elements have a current capacity of 1 kA class in 77 K. In order to measure transport properties in fault conditions, a half cycle of sinusoidal current up to about 4 kA was applied to the elements. I-shaped short samples with 0.5 mm thick NiCr showed an endurance voltage of 13 V(electric field strength of 6.5 V/cm) without damage, when the peak value of applied current was 4.2 kA. For the meander-shaped samples, endurance voltage of 92 V was observed through one element, when the peak value of applied current was 4.0 kA. This voltage is about four times higher than that tolerated by conventional meander-shaped elements that have no NiCr bypass reinforcement. In the case of metal bypassing both sides of a superconductor in fault conditions, fault current flows through the metal bypasses. Then, both the superconductor and metal bypass expand by Joule heating. Therefore, the mechanical stress on a superconductor is reduced relative to the presence of metal bypasses. It is considered that metal bypasses lead to high durability against thermal shock.

ジャーナルPhysica C: Superconductivity and its applications
出版ステータス出版済み - 10月 2004

!!!All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学
  • エネルギー工学および電力技術
  • 電子工学および電気工学


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