1998 Fiscal Year Final Research Report Summary
Fabrication and evaluation of conductor cables using Ag-sheathed high-Tc superconductor tapes
| Project/Area Number |
08455134
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電力工学・電気機器工学
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| Research Institution | Toyohashi University of Technology |
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Principal Investigator |
OOTA Akio Toyohashi Univ.of Tech.Professor, 工学部, 教授 (10124728)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUNAGA Tetsuya Gifu National College Lecturer, 電子制御工学科, 講師 (50249794)
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| Project Period (FY) |
1996 – 1998
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| Keywords | high-Tc super-conductors / power cable / Ag-sheathed wires / Bi2223 / AC transport loss / self fields |
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| Research Abstract |
We investigated the AC transport losses in self-fields for Ag-sheathed multifilamentary tapes that are the most promising for the strands of power transmission cables. The experimental results are explained by the theory of Norris for an elliptical superconductor with the same critical current, nearly independent of filament number or superconductor geometry. The filament twist neither causes notable influence on the e filaments, although the main contribution to the loss behavior nor equalizes the current distribution in th losses comes from the hysteresis loss.
We proposed a new method to calculate the shape of field-free core, the current distribution and. accordingly the AC transport losses in sell fields as a parameter of current amplitude 10 for straight superconductor tapes with the arbitrary sectional geometry. The AC transport losses for. rectangular tapes behave as a thin strip superconductor in high 10 values near critical current, while showing a gradual deviation from this
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behavior as 10 is lowered. A decrease in the aspect ratio of width to thickness in the rectangular tape makes the deviation more remarkable. We applied this method to calculations on the AC transport losses for two kinds of 7-filamentary tapes with different filament arrangements. We compared the results with the experimental behaviors of the losses for Ag-sheathed Bi2223 tapes, and found that the measured losses are explained by the calculated results of loss-density distribution. The influence of filament arrangement on the loss behaviors is suppressed as the filament number increases to 37, from 7.
Using this method, we made numerical calculations on the losses for models of parallel-conductors cables composed of a single- or a multi-layer configurations using rectangular superconductor tapes as the strands. The loss values of cable conductors are strongly influenced by the tape gap on a cylindrical former or a separation between the face-to-face tapes in each layer. The results suggest that the improvement of tape and cable structure, i.e., the arrangement of superconducting cores in the cable conductors, is important to suppress the losses generating in the cable conductors under AC current transmission. Less
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