Electromagnetic properties in parallel conductors composed of Bi2223 multifilamentary wires for power transformer windings

Iwakuma, Masataka; Funaki, K.; Shinohara, H.; Sadohara, Takeshi; Takeo, M.; Yamafuji, Kaoru; Konoo, M.; Kasagawa, Yusuke; Okubo, Kenji; Itoh, I.; Nose, S.; Ueyama, M.; Hayashi, Kazuhiko; Sato, K.

doi:10.1109/77.614489

Cited by 27 publications

(4 citation statements)

References 1 publication

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“…For a wide application of oxide superconducting parallel conductors, the accurate grasp of their fundamental electromagnetic properties, especially the quantitative investigation of the additional ac loss, is indispensable. We reported the ac loss properties of superconducting parallel conductors partly in [1,9]. In a previous study, we investigated only the non-saturation case where the induced shielding current is less than the critical current of a strand and discussed only the dependence of the ac loss on the deviation length of the transposition point from the optimum one semi-quantitatively.…”

Section: Introductionmentioning

confidence: 99%

Theoretical analysis on ac loss properties of two-strand parallel conductors composed of superconducting multifilamentary strands

Iwakuma

Tanaka

Funaki

2002

Supercond. Sci. Technol.

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The ac loss properties of two-strand parallel conductors composed of superconducting multifilamentary strands were theoretically investigated. The constituent strands generally need to be insulated and transposed for the sake of uniform current distribution and low ac loss. In case the transposition points deviate from the optimum ones, shielding current is induced according to the interlinkage magnetic flux of the twisted loop enclosed by the insulated strands and the contact resistances at the terminals. It produces an additional ac loss. Supposing a simple situation where a two-strand parallel conductor with one-point transposition is exposed to a uniform ac magnetic field, the basic equations for the magnetic field were proposed and the theoretical expressions of the additional ac losses derived. As a result, the following features were shown. The additional ac loss in the non-saturation case, where the induced shielding current is less than the critical current of a strand, is proportional to the square of the magnetic field amplitude and the square of deviation length in transposition and has a Debye-type frequency dependence. On the other hand, in the saturation case, the additional ac loss is nearly proportional to the field amplitude and the deviation length in transposition. It has no frequency dependence at a higher frequency than the critical frequency.

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Section: Introductionmentioning

confidence: 99%

Theoretical analysis on ac loss properties of two-strand parallel conductors composed of superconducting multifilamentary strands

Iwakuma

Tanaka

Funaki

2002

Supercond. Sci. Technol.

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“…Therefore, in this study, YBCO tapes are electrically insulated to decrease this coupling loss. By contrast, since the transport current is transposed among YBCO tapes in the bundle conductor at only the joints with current leads and the connection between pancake coils, the appropriate transposition of YBCO tapes in the bundle conductor will be required at adequate position [9].…”

Section: B Ybco Laminated Bundle Conductormentioning

confidence: 99%

Quench Behavior and Protection in Cryocooler-Cooled YBCO Pancake Coil for SMES

Ishiyama

Ueda

Aoki

et al. 2011

IEEE Trans. Appl. Supercond.

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The thermal behavior of a high-temperature superconducting (HTS) coil is significantly different from that of lowtemperature superconducting (LTS) coil because it has a greater volumetric heat capacity at the temperature required for practical use. Therefore, the possibility of quench in HTS coils is much lower than that in LTS coils. In the application of the YBCO coil to Superconducting Magnetic Energy Storage (SMES) system, electrical charging and discharging are repeated; therefore, the superconducting characteristics of the YBCO coated conductor may deteriorate as a result of cyclic subjection to tensile strain. To enhance the reliability and safety of HTS coil, protection scheme assuming a quench is also required for HTS coil. In this study, we focus on the coil wound with YBCO laminated bundle (parallel) conductor supposing SMES application and investigate the characteristics of normal-zone propagation and the thermal behavior within the coil during a quench by using a newly developed computer code based on the finite element method and an equivalent circuit. And we also propose a quench detection method using observation of nonuniform current in YBCO laminated bundle conductor and discuss the validity of the detection method comparing with conventional quench-voltage detection.

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“…The ac loss properties of superconducting parallel conductors have not been investigated at all. Therefore, before the fabrication of the transformers and the pulse coil, we started the study of the ac loss and current distribution properties of superconducting parallel conductors [1,5]. We also made a detailed theoretical analysis of the ac losses for a simple case when a two-strand parallel conductor with one-point transposition was exposed to a spatially uniform magnetic field [6].…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the ac loss properties of two-strand parallel conductors composed of superconducting multifilamentary strands

Iwakuma

Tanaka

Funaki

2002

Supercond. Sci. Technol.

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The ac loss properties of two-strand superconducting parallel conductors were experimentally investigated by using NbTi multifilamentary strands with a rectangular cross section. We prepared the simple situation that was supposed in the previous theoretical study (M Iwakuma et al 2002 Supercond. Sci. Technol. 15 1525. The two insulated strands were sparsely co-wound into one-layer solenoidal coils. They were transposed only once and soldered at both ends. The ac losses in the sample coils were measured by a pick-up-coil method by applying uniform ac magnetic field parallel to the coil axis and comparing it with the theoretical results. The validity of the theoretical expressions derived in the previous paper was verified by the quantitative agreement with experiment in all the aspects, i.e. the dependencies on frequency, field amplitude and the deviation length in transposition in both the non-saturation and saturation cases and also the threshold condition between them. The results obtained support the theoretical prediction that the additional ac loss due to the formation of superconducting parallel conductors can be much reduced by transposition whether the induced shielding current reaches the critical current of a strand or not.

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Electromagnetic properties in parallel conductors composed of Bi2223 multifilamentary wires for power transformer windings

Cited by 27 publications

References 1 publication

Theoretical analysis on ac loss properties of two-strand parallel conductors composed of superconducting multifilamentary strands

Theoretical analysis on ac loss properties of two-strand parallel conductors composed of superconducting multifilamentary strands

Quench Behavior and Protection in Cryocooler-Cooled YBCO Pancake Coil for SMES

Experimental study on the ac loss properties of two-strand parallel conductors composed of superconducting multifilamentary strands

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