1998 Fiscal Year Final Research Report Summary
Electrical Insulation in Superconducting Power Apparatus
| Project/Area Number |
08305009
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | Nagoya University |
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Principal Investigator |
OKUBO Hitoshi Nagoya Univ., Graduate School of Eng., Prof., 工学研究科, 教授 (90213660)
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| Co-Investigator(Kenkyū-buntansha) |
HAYAKAWA Naoki Nagoya Univ., Graduate School of Eng., Assoc.Prof., 大学院・工学研究科, 助教授 (20228555)
ISOJIMA Shigeki Sumitomo Electric Industries, Ltd., Electric Power System Technology Research la, 電力システム技術研究所, 研究員
SAKAI Yosuke Hokkaido Univ., Greduate School of Eng., Prof., 大学院・工学研究科, 教授 (20002199)
KOSAKI Masamitsu Gifu National College of Technology, President, 校長 (80023191)
HARA Msanori Kyushu Univ., Graduate School of Information Science and Electrical Eng., Prof., 大学院・システム情報科学研究科, 教授 (30039127)
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| Project Period (FY) |
1996 – 1998
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| Keywords | superconductivity / power apparatus / electrical insulation / Liquid helium / liquid nitrogen / Bubble / Breakdown / Partial discharge |
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| Research Abstract |
A.Evaluation of electrical insulation characteristics for superconducting power apparatus
(1) Degradation mechanisms of breakdown voltage of liquid helium under quench environment of superconducting power apparatus were elucidated. The quench-induced dynamic breakdown characteristics were systematized by post-quench thermal energy, gap length and pressure of liquid helium, which will contribute to the practical insulation design of superconducting power apparatus.
(2) The trial model of extruded EPR insulation DC superconducting cable was made and the change of the characteristic of the high temperature superconductor due to the EPR extrusion and the DC electrical insulation performance of EPR at cryogenic temperature were examined. It was shown that the characteristic deterioration of the high temperature superconductor was a little even if extruded EPR insulation was applied. The mechanical characteristic of EPR at cryogenic temperature and the DC electrical insulation performance have
… More
been approved excellent These results promise the realization of the huge power transportation by using the extruded EPR insulation DC superconducting cable in the future.
(3) Electrical insulation design of superconducting turbo generator was studied. Relations between the behavior of helium bubbles in liquid helium and breakdown characteristics of the liquid were investigated in high speed rotating condition.
B.Evaluation of withstand voltage characteristic of electrical insulating materials for superconducting magnets
(1) Partial discharge (PD) generated in a composite insulation system composed of liquid nitrogen and solid insulation material is considerably suppressed by increasing pressure. PD characteristics in solid insulator with an artificial void are strongly influenced by ambient temperature. At a higher voltage stress, the insulator lifetime can be much shorter at liquid nitrogen temperature than room temperature.
(2) The bubble motion in liquid N_2 in microgravity environment was observed and the drift velocity of electrons in N_2/Ar mixtures was measured. The low mobility electrons in high fraction of N_2 in low fields were shown to be localized in some multiparticle.
(3) The longer gap breakdown voltages of a uniform field gap for 50Hz ac, dc and 1.4/50 micro-sec lightning impulse voltage applications in gaseous nitrogen and air are studied at a room temperature and a cryogenic temperature (about 93K). It is confirmed from the experimental results that the Paschen's law holds in any cases.
(4) Resistance against treeing degradation of extruded polymer, which is promising as electrical insulating system at cryogenic temperature, was investigated under existence of He gas assuming leakage accident. It was clarified that He gas decreases treeing resistance at room temperature, but not at cryogenic temperature. Less
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