Fabrication transport properties of QMG current limiting elements

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

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)750-755
Number of pages6
JournalPhysica C: Superconductivity and its Applications
Volume412-414
Issue numberSPEC. ISS.
DOIs
Publication statusPublished - Oct 1 2004

Fingerprint

bypasses
Transport properties
transport properties
Metals
Fabrication
fabrication
Superconducting materials
meanders
Durability
metals
Reinforcement
Electric potential
endurance
reinforcement
durability
Joule heating
Electric fault currents
electric potential
Thermal shock
Chemical elements

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

Cite this

Morita, M., Hirano, H., Hayashi, H., Terazono, K., Kajikawa, K., Funaki, K., & Hamajima, T. (2004). Fabrication transport properties of QMG current limiting elements. Physica C: Superconductivity and its Applications, 412-414(SPEC. ISS.), 750-755. https://doi.org/10.1016/j.physc.2003.12.070

Fabrication transport properties of QMG current limiting elements. / Morita, Mitsuru; Hirano, H.; Hayashi, H.; Terazono, K.; Kajikawa, Kazuhiro; Funaki, K.; Hamajima, T.

In: Physica C: Superconductivity and its Applications, Vol. 412-414, No. SPEC. ISS., 01.10.2004, p. 750-755.

Research output: Contribution to journalArticle

Morita, M, Hirano, H, Hayashi, H, Terazono, K, Kajikawa, K, Funaki, K & Hamajima, T 2004, 'Fabrication transport properties of QMG current limiting elements', Physica C: Superconductivity and its Applications, vol. 412-414, no. SPEC. ISS., pp. 750-755. https://doi.org/10.1016/j.physc.2003.12.070
Morita, Mitsuru ; Hirano, H. ; Hayashi, H. ; Terazono, K. ; Kajikawa, Kazuhiro ; Funaki, K. ; Hamajima, T. / Fabrication transport properties of QMG current limiting elements. In: Physica C: Superconductivity and its Applications. 2004 ; Vol. 412-414, No. SPEC. ISS. pp. 750-755.
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