Faculty Profiles - KOJIMA Hiroki

Presentations -

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Breakdown in Vacuum Invited International conference

H. Kojima

31st International Symposium on Discharge and Electrical Insulation in Vacuum 2025.9.21 Sichuan University

Dynamic Breakdown Characteristics of Liquid Nitrogen for Superconducting Fault Current Limiters in Multi-terminal HVDC Systems International conference

N. Hayakawa, D. Nishizawa, K. Naganawa, H. Kojima

17th European Conference on Applied Superconductivity 2025.9.23 European Society for Applied Superconductivity

Phase-Resolved Partial Discharge Pattern in Aluminum Foil/Oil-Impregnated Paper Composite Insulation System for Insulation Diagnosis of Capacitor Voltage Transformers International conference

Y. Jinno, Y. Nagaki, H. Kojima, M. Yoshida, N. Hayakawa

24th International Symposium on High Voltage Engineering 2025.8.27 The University of Tokyo

Electrical Insulating Properties of Cellulose Nano-Fiber (CNF) Board for Electrical Insulation Systems of Rotating Machines International conference

K. Kimura, H. Kojima, N. Hayakawa, N. Furuta, H. Okumura, A. Anjiki, Y. Yamanaka, T. Iwanaga, T. Okamoto

24th International Symposium on High Voltage Engineering 2025.8.26 The University of Tokyo

Deconditioning during Spark Conditioning for Vacuum Circuit Breaker International conference

F. Ueno, H. Kojima, N. Hayakawa, H. Fukuda, K. Yamamura, K. Nagatake

24th International Symposium on High Voltage Engineering 2025.8.26 The University of Tokyo

Flashover Characteristics of Permittivity and Conductivity Graded Materials in Dry Air for DC-GIS Spacer under DC/Impulse Superimposed Voltage International conference

N. Hayakawa, R. Sugimoto, H. Kojima

24th International Symposium on High Voltage Engineering 2025.8.28 The University of Tokyo

ガス絶縁機器におけるSF6代替ガスの国内外の最新の研究・技術開発動向（１） ―過去からの研究・技術開発の経緯と調査専門委員会活動―

岡部成光，小島寛樹，安岡孝倫，神足将司，渡辺泰一，阿部剛志

電気学会放電・プラズマ・パルスパワー研究会 2025.6.13 電気学会放電・プラズマ・パルスパワー技術委員会

Breakdown Characteristics of Streaming Lubricating Oil toward Higher Power Density Motors for Electric Powered Aircraft International conference

N. Hayakawa, N. Nakazawa, S. Noguchi, H. Kojima, N. Aruga, K. Utatsu, S. Watanabe

23rd IEEE International Conference on Dielectric Liquids 2025.5.21 IEEE Dielectrics and Electrical Insulation Society

真空中高周波交流コンディショニングによる到達耐圧の推定

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和7年電気学会全国大会 2025.3.18 電気学会

真空中固体絶縁物上の帯電形成と電界変歪による貫通破壊

窪田愛斗，小島寛樹，道念大樹，山口信一，早川直樹

令和7年電気学会全国大会 2025.3.20 電気学会

直流超電導限流器動作時における液体窒素の動的絶縁破壊特性

西澤大将，永縄巧輔，小島寛樹，早川直樹

令和7年電気学会全国大会 2025.3.20 電気学会

セルロースナノファイバー（CNF）成形板における絶縁耐力の湿度依存性

木村啓韻，小島寛樹，早川直樹，古田尚，奥村浩史，安食厚志，山中雄太，岩永拓実，岡本徹志

令和7年電気学会全国大会 2025.3.20 電気学会

電動推進航空機用モータにおける流動潤滑油の絶縁破壊特性の体積効果

中澤尚輝，野口真平，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

令和7年電気学会全国大会 2025.3.18 電気学会

電動推進航空機用モータにおける潤滑油の絶縁破壊特性の温度・流量依存性

野口真平，中澤尚輝，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

令和7年電気学会全国大会 2025.3.18 電気学会

回転機絶縁システムへの適用に向けた真空加圧含浸によるセルロースナノファイバー成形板の比誘電率への影響

岩永拓実，岡本徹志，山中雄太，木村啓韻，小島寛樹，早川直樹，古田尚，奥村浩史，安食厚志

令和7年電気学会全国大会 2025.3.18 電気学会

アルミ箔/油浸紙複合絶縁系における油浸紙貫通時の部分放電特性

神野裕亮，永木雄也，小島寛樹，吉田昌展，早川直樹

令和7年電気学会全国大会 2025.3.19 電気学会

ε/σ-FGM絶縁スペーサの乾燥空気中における直流/雷インパルス重畳フラッシオーバ特性

杉本遼次，木村友哉，小島寛樹，早川直樹

令和7年電気学会全国大会 2025.3.19 電気学会

真空中スパークコンディショニングにおけるデコンディショニング

上野楓真，小島寛樹，福田英昭，山村健太，早川直樹

令和7年電気学会全国大会 2025.3.18 電気学会

繰返しサージ電圧下におけるツイストペアの絶縁寿命推定に関する一検討

宮路仁崇，石川裕卓，大竹泰智，小島寛樹，早川直樹

電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧合同研究会 2025.1.23 電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧技術委員会

Electrode Material Dependence of Dielectric Strength Improvement in High Frequency AC Conditioning in Vacuum International conference

R. Konagi, H. Kojima, N. Hayakawa, S. Iitsuka, M. Kobayashi

7th International Conference on Electric Power Equipment – Switching Technology 2024.11.12 Xi'an Jiaotong University, Xiamen University of Technology

Event date： 2024.11

Language：English Presentation type：Oral presentation (general)

Venue：Xiamen Country：China

Spark conditioning by repeated breakdowns (BDs) with AC voltage application is an effective method for improving dielectric strength in vacuum. During AC conditioning, the multiple BDs occur successively in a half cycle of AC voltage application. It is considered that the multiple BDs are harmful for conditioning and triggered due to the previous BD in the same half cycle. In our previous research, we have confirmed that high frequency AC conditioning suppress the multiple BDs and improves dielectric strength for the Cu electrodes. In this paper, we discuss the electrode material dependence of the dielectric strength improvement in high frequency AC conditioning in vacuum. We compare high frequency AC conditioning effect for the stainless steel (SUS) electrodes with that for the Cu electrodes. Experimental results have revealed that the high frequency AC conditioning improved the dielectric strength by 16% for the Cu electrodes, but did not almost improve for the SUS electrodes. It is considered that the harmful effects of the multiple BDs are significant for electrode materials with high electrical and thermal conductivities such as Cu, and the dielectric strength improvement by the suppression of the multiple BDs due to high frequency AC conditioning is expected to be useful for such electrode materials.

DOI： 10.1109/ICEPE-ST61894.2024.10792561

Scopus

真空沿面帯電・放電進展メカニズムおよび傾斜機能材料による三重点電界緩和 Invited

小島寛樹

第14回アドバンストSEMセミナー 2024.10.29 日立ハイテクアドバンストSEMテクノロジ特別共同研究事業

Partial Discharge Progress and Breakdown in Oil-Impregnated Paper Insulation System of Capacitor Voltage Transformers International conference

Y. Nagaki, K. Hayashi, H. Kojima, M. Yoshida, N. Hayakawa

10th International Conference on Condition Monitoring and Diagnosis 2024.10.24 The Korean Institute of Electrical Engineers

Event date： 2024.10

Language：English Presentation type：Poster presentation

Venue：Gangwon-do Country：Korea, Republic of

In this paper, towards the insulation diagnosis of capacitor voltage transformers (CVTs) based on partial discharge (PD) measurements, PD progress and breakdown (BD) characteristics in aluminum foil/oil-impregnated paper composite insulation system were discussed, especially in the transition from creeping PD to penetrating PD. PD extended in the creeping direction of oil-impregnated papers with bubbles, eroded and penetrated the 1st layer of oil-impregnated paper. The penetrating PD with large charge, long length and red light emission extended in H2-based gases. PD sequentially penetrated the laminated oil-impregnated papers and led to BD.

DOI： 10.23919/CMD62064.2024.10766131

Scopus

Partial Discharge Characteristics of Aluminum Foil/Oil-Impregnated Paper Composite Insulation System with Misaligned Aluminum Foils Invited International conference

N. Hayakawa, K. Hayashi, Y. Nagaki, H. Kojima, M. Yoshida

10th International Conference on Condition Monitoring and Diagnosis 2024.10.22 The Korean Institute of Electrical Engineers

Event date： 2024.10

Language：English Presentation type：Oral presentation (invited, special)

Venue：Gangwon-do Country：Korea, Republic of

Capacitor voltage transformers (CVTs) composed of aluminum foil/oil-impregnated paper composite insulation system have been operated over 30 years in substations. The insulation diagnosis of CVTs are expected to be based on the measurement of partial discharge (PD) leading to breakdown (BD). The misalignment of aluminum foil electrodes in the fabrication and/or operation of CVTs may cause PD. This paper discussed the PD characteristics of misaligned aluminum foil electrodes toward the insulation diagnosis of CVTs. PD progressed in the creeping direction of oil-impregnated papers within the misalignment width of aluminum foil electrode peripheries. The creeping PD eroded the surface of the 1st layer of oil-impregnated paper and penetrated the other layers, leading to BD.

DOI： 10.23919/CMD62064.2024.10766108

Scopus

Concept of Condition Monitoring for Capacitor Voltage Transformers International conference

H. Isaji, Y. Nagaki, M. Yoshida, H. Kojima, N. Hayakawa

10th International Conference on Condition Monitoring and Diagnosis 2024.10.22 The Korean Institute of Electrical Engineers

Event date： 2024.10

Language：English Presentation type：Poster presentation

Venue：Gangwon-do Country：Korea, Republic of

It is important to establish methods for detecting internal abnormalities and diagnosing the accuracy of the transformation ratio of instrument transformers. In the case of a capacitor voltage transformer (CVT) with multiple oil-impregnated paper capacitors connected in series, partial discharge (PD) occurs due to the deterioration of capacitor elements. When PD is extended, the capacitor electrode is short-circuited and the transformation ratio changes. Namely, the diagnostic of transformation ratio is effective for detecting internal abnormalities of CVT. The change in the voltage division ratio was investigated by experimentally reproducing the phenomena from the generation of PD to a short circuit in the capacitor elements. On the other hand, the effect on the transformation ratio due to the difference in the position and number of short-circuited capacitor elements in the CVT was simulated. In a digital substation, secondary voltage values of several CVTs are obtained simultaneously using intelligent electronic devices (IED). Therefore, using programmable devices supported by the IEC 61850 communication protocol, data can be acquired from IEDs and CVT condition monitoring can be achieved with simple calculations.

DOI： 10.23919/CMD62064.2024.10766186

Scopus

回転機絶縁システム適用に向けたセルロースナノファイバー（CNF）成形板の電気絶縁特性

木村啓韻，小島寛樹，早川直樹，古田尚，奥村浩史，安食厚志，山中雄太，岩永拓実，岡本徹志

第55回電気電子絶縁材料システムシンポジウム 2024.9.27 電気学会基礎・材料・共通部門誘電・絶縁材料技術委員会

電動推進航空機用モータの高出力密度化に向けた流動潤滑油の絶縁破壊特性

中澤尚輝，野口真平，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

第55回電気電子絶縁材料システムシンポジウム 2024.9.26 電気学会基礎・材料・共通部門誘電・絶縁材料技術委員会

多端子直流送電システムにおける超電導限流器の限流協調

西澤大将，小島寛樹，中村綾花，岩田幹正，早川直樹

電気学会電力技術/電力系統技術合同研究会 2024.9.20 電気学会電力技術/電力系統技術委員会

Improvement of Flashover Voltage by Functionally Graded Materials in Gas Insulated Power Apparatus Invited International conference

H. Kojima

2024 China-Japan Forum on The Development of Electrical Materials 2024.9.7 State Key Laboratory of Electrical Insulation and Power Equipment, Department of International Cooperation & Exchanges, Xi'an Jiaotong University

真空中スパークコンディショニングによる絶縁耐力向上における放電電荷量と放電電流二乗積分の相乗効果

上野楓真，小島寛樹，福田英昭，山村健太，早川直樹

令和6年電気学会電力・エネルギー部門大会 2024.9.4 電気学会電力・エネルギー部門

回転機絶縁システム適用に向けたセルロースナノファイバー成形板の樹脂含浸性と吸湿特性

岩永拓実，山下優，岡本徹志，古田尚，奥村浩史，安食厚志，山中雄太，木村啓韻，小島寛樹，早川直樹

令和6年電気学会基礎・材料・共通部門大会 2024.9.3 電気学会基礎・材料・共通部門

技術委員会の活動の拡がりとその成果 Invited

小島寛樹

令和6年電気学会基礎・材料・共通部門大会 2024.9.2 電気学会基礎・材料・共通部門

アルミ箔/油浸紙複合絶縁系における部分放電による気泡と油浸紙貫通の関係

神野裕亮，永木雄也，小島寛樹，吉田昌展，早川直樹

令和六年度電気・電子・情報関係学会東海支部連合大会 2024.8.29 電気学会東海支部，電子情報通信学会東海支部，情報処理学会東海支部，照明学会東海支部，映像情報メディア学会東海支部，日本音響学会東海支部，IEEE名古屋支部

多端子直流送電システムにおける超電導限流器の臨界電流協調

西澤大将，小島寛樹，中村綾花，岩田幹正，早川直樹

令和六年度電気・電子・情報関係学会東海支部連合大会 2024.8.28 電気学会東海支部，電子情報通信学会東海支部，情報処理学会東海支部，照明学会東海支部，映像情報メディア学会東海支部，日本音響学会東海支部，IEEE名古屋支部

超電導限流器が導入された直流送電システムにおける限流シミュレーション

熊雨傑，西澤大将，小島寛樹，早川直樹

真空中スパークコンディショニングで生成される陰極表面上の微小突起形状

上野楓真，小島寛樹，福田英昭，山村健太，早川直樹

セルロースナノファイバー（CNF）成形板の絶縁破壊電界の湿度依存性

木村啓韻，小島寛樹，早川直樹，古田尚，奥村浩史，安食厚志，山中雄太，岩永拓実，岡本徹志

電動推進航空機用モータ絶縁に適用する潤滑油の絶縁破壊特性における温度・流量依存性

野口真平，中澤尚輝，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

電動推進航空機用モータ絶縁に適用する潤滑油の絶縁破壊特性における水分量依存性

中澤尚輝，野口真平，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

導電率/誘電率傾斜機能材料（ε/σ-FGM）を適用したDC-GISスペーサにおける電界緩和効果の導電率分布依存性

杉本遼次，小島寛樹，早川直樹

ガス絶縁電力機器における絶縁技術課題の変遷

小島寛樹

電気学会電気技術史研究会 2024.7.3 電気学会電気技術史技術委員会

交流電圧印加による真空中固体絶縁物上の正帯電形成過程

杉浦拓真，窪田愛斗，小島寛樹，道念大樹，山口信一，早川直樹

令和6年電気学会全国大会 2024.3.16 電気学会

セルロースナノファイバー（CNF）成形板の部分放電および絶縁破壊電界の厚さ依存性

木村啓韻，北直樹，小島寛樹，早川直樹，岩永拓実，山下優，岡本徹志，古田尚，奥村浩史，山中雄太

令和6年電気学会全国大会 2024.3.14 電気学会

超電導限流器が導入された多端子直流送電システムの限流協調

西澤大将，小島寛樹，早川直樹

令和6年電気学会全国大会 2024.3.16 電気学会

電動推進航空機用モータ絶縁に適用する流動潤滑油の絶縁破壊特性

中澤尚輝，野口真平，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

令和6年電気学会全国大会 2024.3.16 電気学会

アルミ箔/油浸紙複合絶縁系における部分放電による油浸紙損傷と絶縁破壊

林恭平，神野裕亮，永木雄也，小島寛樹，吉田昌展，早川直樹

令和6年電気学会全国大会 2024.3.14 電気学会

直流GIS/GIL用σ-FGM絶縁スペーサの乾燥空気中におけるフラッシオーバ特性

杉本遼次，小島寛樹，早川直樹

令和6年電気学会全国大会 2024.3.14 電気学会

真空中インパルス絶縁破壊時における陽極表面からの金属粒子の飛散

北直樹，上野楓真，小島寛樹，福田英昭，山村健太，早川直樹

令和6年電気学会全国大会 2024.3.14 電気学会

真空中高周波交流コンディショニングの絶縁耐力向上効果における電極材料依存性

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和6年電気学会全国大会 2024.3.14 電気学会

油浸紙絶縁系のコンデンサ形計器用変圧器における部分放電進展・絶縁破壊メカニズム

永木雄也，林恭平，神野裕亮，小島寛樹，吉田昌展，早川直樹

電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧合同研究会 2024.1.20 電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧技術委員会

Fabrication and Flashover Characteristics of Permittivity and Conductivity Graded Materials (ε/σ-FGM) for DC-GIS Spacers International conference

R. Sugimoto, T. Kato, H. Kojima, N. Hayakawa

2023 International Symposium on Electrical Insulating Materials 2023.9.25 IEEJ Technical Committee on Dielectrics and Electrical Insulation

Event date： 2023.9

Language：English Presentation type：Oral presentation (general)

Venue：Matsue Country：Japan

The progressive development of HVDC transmission system has urged us to develop a novel technique in supporting the performance of DC power apparatus. Functionally Graded Materials (FGM) are one of the techniques that allow us to control the electric field distribution within the DC insulation system. Our previous works have analytically revealed that FGM with spatial permittivity ε and conductivity σ distributions applied to a 320 kV DC-GIS spacer could reduce the maximum electric field under all DC operating conditions. In this paper, we fabricated a cone-type ε/σ-FGM spacer for DC-GIS and experimentally verified its flashover voltage improvement effect.

DOI： 10.23919/ISEIM60444.2023.10329009

Scopus

放電・プラズマ・パルスパワー分野における研究・技術開発の歩み今後の展望 Invited

小島寛樹，佐々木徹，高橋克幸，稲田優貴，中川雄介，中野裕介

令和5年電気学会基礎・材料・共通部門大会 2023.9.8 電気学会基礎・材料・共通部門

回転機絶縁システムへの適用を目指したセルロースナノファイバー複合体の基礎特性

岩永拓実，山下優，岡本徹志，小島寛樹，早川直樹，古田尚，奥村浩史，安食厚志，山中雄太，梅本貴弘

令和5年電気学会基礎・材料・共通部門大会 2023.9.9 電気学会基礎・材料・共通部門

真空中沿面放電の初期進展過程における電子軌道追跡による過渡帯電・発光特性

杉浦拓真，小島寛樹，早川直樹，中野裕介

令和5年電気学会基礎・材料・共通部門大会 2023.9.7 電気学会基礎・材料・共通部門

DC-GIS用ε/σ-FGMスペーサの作製および直流耐圧向上効果

杉本遼次，加藤拓夢，小島寛樹，早川直樹

令和5年電気学会電力・エネルギー部門大会 2023.9.6 電気学会電力・エネルギー部門

高融点陰極表面への低融点陽極材料の付着による真空中コンディショニング効果の抑制

北直樹，小島寛樹，福田英昭，山村健太，早川直樹

令和5年電気学会電力・エネルギー部門大会 2023.9.6 電気学会電力・エネルギー部門

真空中高周波交流コンディショニングにおける耐圧向上効果の周波数および印加電圧依存性

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和5年電気学会電力・エネルギー部門大会 2023.9.6 電気学会電力・エネルギー部門

Temperature Rise in Conductivity Graded Materials (σ-FGM) Spacer for HVDC GIS/GIL International conference

Rachmawati, H. Kojima, N. Hayakawa, H. Okubo

23rd International Symposium on High Voltage Engineering 2023.8.29 The Department of Electronic and Electrical Engineering of the University of Strathclyde

Event date： 2023.8 - 2023.9

Language：English Presentation type：Oral presentation (general)

Venue：Glasgow Country：United Kingdom

Functionally graded permittivity and conductivity materials (ε/σ-FGM) application is a novel method to improve electric field distribution around HVDC GIS/GIL spacer. Since there is interdependency between temperature and conductivity, in this paper, the relationship between conductivity and the semi-conductive SiC filler concentrations in epoxy-based ε/σ-FGM spacer is clarified, and the effect of SiC filler concentrations to the leakage current (ILC), maximum temperature (Tmax), as well as maximum conductivity (σmax) are investigated through electric field and thermal simulation. The simulation results revealed that Tmax started to exceed the temperature of HV conductor when σmax exceeds 4×10-9 S/m and ILC is of a few hundreds of nA. Since this criterion corresponds to 21 vol% SiC-filled epoxy composite in σ-FGM, 5–10 vol% SiC-filled epoxy composite in the specified U-type σ-FGM spacer has low enough conductivity not to cause temperature rise.

DOI： 10.1049/icp.2024.0516

Scopus

Flashover Voltage of Permittivity Graded Materials (ε-FGM) Spacer with Metallic Particles in SF₆ Gas International conference

N. Hayakawa, H. Kato, T. Kato, H. Kojima, S. Kamohara, Y. Hoshina

23rd International Symposium on High Voltage Engineering 2023.8.29 The Department of Electronic and Electrical Engineering of the University of Strathclyde

Event date： 2023.8 - 2023.9

Language：English Presentation type：Poster presentation

Venue：Glasgow Country：United Kingdom

Functionally graded materials with spatial distribution of permittivity (ε-FGM) are promising for the compact, efficient and environmentally benign GIS spacers. In this paper, for the practical insulation design and installation of ε-FGM spacers to GIS, the risk of metallic particles on ε-FGM spacers is investigated. Experimental results using the fabricated cone-type ε-FGM spacers revealed that the metallic particles in permittivity-grading area on convex surface were the most harmful and reduced the flashover voltage in SF6 gas by about 40 %, compared with that without the particles. The flashover voltage was almost equal to that of the conventional spacers with a uniform permittivity distribution and the metallic particles in the maximum electric field area on concave surface. Thus, the risk of metallic particles on ε-FGM spacers can be almost the same as that of the conventional spacers.

DOI： 10.1049/icp.2024.0618

Scopus

Non-destructive Measurement of Permittivity Distribution in Permittivity Graded Materials (ε-FGM) by X-ray Computed Tomography International conference

N. Hayakawa, T. Kato, H. Kojima, H. Yanase, K. Okamoto

23rd International Symposium on High Voltage Engineering 2023.8.29 The Department of Electronic and Electrical Engineering of the University of Strathclyde

Event date： 2023.8 - 2023.9

Language：English Presentation type：Oral presentation (general)

Venue：Glasgow Country：United Kingdom

Toward the compact gas insulated switchgears (GIS), we have been investigating a novel electric field grading technique around the GIS spacer by “functionally graded materials (FGM)” with spatial distribution of permittivity (ε-FGM). We have already designed and fabricated the cone-type ε-FGM spacer samples with the relative permittivity (εr) of 10.0-4.0 for an actual 245 kV-class GIS as well as those with εr of 12.7-4.0 for its 1/4-sized model and revealed the improvement of flashover voltage in SF6 gas through experiments and calculations. It is important to develop a non-destructive method to measure and verify the permittivity distribution inside the spacer to realize the practical application of ε-FGM spacers. In this paper, in order to establish the non-destructive measurement method for ε-FGM spacers with the relative permittivity distribution, ZH focused on X-ray computed tomography (CT). We obtained the relationship between the permittivity and the X-ray transmission intensity by analysing different disc-shaped samples (or =12.2-4.2) and verified the measurement possibility of the relative permittivity distribution inside ε-FGM spacer by comparison to the target distribution at the fabrication of ε-FGM spacer.

DOI： 10.1049/icp.2024.0517

Scopus

多端子直流送電システムの超電導限流器動作時における液体窒素の動的絶縁破壊電界の推定

西澤大将，小島寛樹，早川直樹

令和五年度電気・電子・情報関係学会東海支部連合大会 2023.8.28 電気学会東海支部，電子情報通信学会東海支部，情報処理学会東海支部，照明学会東海支部，映像情報メディア学会東海支部，日本音響学会東海支部，IEEE名古屋支部

真空中コンディショニングにおけるギャップ長と最適放電電荷量の関係

北直樹，小島寛樹，福田英昭，山村健太，早川直樹

令和五年度電気・電子・情報関係学会東海支部連合大会 2023.8.29 電気学会東海支部，電子情報通信学会東海支部，情報処理学会東海支部，照明学会東海支部，映像情報メディア学会東海支部，日本音響学会東海支部，IEEE名古屋支部

真空中高周波交流コンディショニングにおける多重絶縁破壊の時間間隔の印加電圧依存性

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

真空中沿面放電の初期進展過程における絶縁物表面への電界入射方向と2次電子なだれの関係

杉浦拓真，小島寛樹，早川直樹

電動推進航空機用モータ絶縁に適用する潤滑油の絶縁破壊特性の流量依存性

中澤尚輝，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

ε/σ-FGM（誘電率/導電率傾斜機能材料）による直流GIS用絶縁スペーサのフラッシュオーバ電圧向上効果

杉本遼次，小島寛樹，早川直樹

アルミ箔/油浸紙複合絶縁系における部分放電特性のアルミ箔電極ズレ幅依存性

林恭平，永木雄也，小島寛樹，吉田昌展，早川直樹

Electrode Material Adhesion between Anode and Cathode in Spark Conditioning in Vacuum International conference

N. Kita, H. Kojima, H. Fukuda, K. Yamamura, N. Hayakawa

30th International Symposium on Discharge and Electrical Insulation in Vacuum 2023.6.26 Technical Committee of Electrical Dicharges, Plasma and Pulsed Power, IEEJ

Event date： 2023.6

Language：English Presentation type：Oral presentation (general)

Venue：Okinawa Country：Japan

We discuss the electrode material adhesion between cathode and anode during spark conditioning process in vacuum, and its effect on dielectric strength in terms of breakdown (BD) charge. We focus on the conditioning effects under rod-plane electrodes with different combination of electrode materials. The material of the rod (cathode) is Cu and that of the plane (anode) is stainless steel (SUS), and their gap length is 1 mm. We observe the electrode surface before and after conditioning experiments. As a result, when BD charge is smaller than 2.0 mC, the anode material (SUS) is found on the cathode (Cu) surface and the dielectric strength becomes high. With increasing BD charge, the adhesion ratio of anode material on the cathode surface decreases, and the dielectric strength also tends to decrease. In the case where BD charge is larger than 2.0 mC, on the contrary, the cathode material (Cu) adheres to the anode (SUS) surface and the dielectric strength is low, which is consistent with the conditioning characteristics when both the cathode and anode are made of Cu. These results indicate that up to a certain BD charge, the anode material adheres to the cathode surface, and above this BD charge the cathode material adheres to the anode surface. When the cathode (Cu) surface is excessively melted, i.e., damaged, the cathode material Cu can adhere to the anode SUS surface. In other words, too large BD charge can not only fails to improve the dielectric strength due to the adhesion of the anode material SUS to the cathode Cu surface, but also causes a critical decrease in the dielectric strength, or deconditioning.

DOI： 10.23919/ISDEIV55268.2023.10201112

Scopus

CiNii Research

Multiple Breakdown Induced by Previous Breakdown in Higher Frequency AC Conditioning International conference

R. Konagi, H. Kojima, S. Iitsuka, M. Kobayashi, N. Hayakawa

30th International Symposium on Discharge and Electrical Insulation in Vacuum 2023.6.29 Technical Committee of Electrical Dicharges, Plasma and Pulsed Power, IEEJ

Event date： 2023.6

Language：English Presentation type：Poster presentation

Venue：Okinawa Country：Japan

We have confirmed that the multiple breakdowns (BDs) occur in a half cycle of AC voltage application in the AC conditioning process in vacuum. In previous research, it has been experimentally confirmed that the higher frequency AC conditioning suppresses the multiple BDs and improves the conditioning effect. In this paper, we discuss how the multiple BDs are induced. By the BD light emission images during AC conditioning, we found that the multiple BDs occurred in close to the previous BD position. This suggests that the multiple BDs were induced by the previous BD. Two possible causes of the multiple BDs are investigated: (a) metal vapor generated by the previous BD and (b) metal particles generated by the previous BD. The diffusion time of metal vapor is much shorter than the time interval for the multiple BDs. Therefore, the multiple BDs may not be induced by metal vapor. On the other hand, for particles of 10 μm order in diameter, the time of collision to the counter electrode matches the time interval of the multiple BDs. Particles of the order of 10 μm in diameter were found on the electrode surface after AC conditioning. These results suggest that the multiple BDs were initiated by metal particles generated by the previous BD and do not contribute to protrusion melting, but damage the electrode surface. Therefore, the higher frequency AC conditioning to suppress the multiple or harmful BDs can be promising for AC conditioning process in vacuum.

DOI： 10.23919/ISDEIV55268.2023.10201218

Scopus

CiNii Research

Applicability of Lubricating Oil Insulation in Higher Power Density Motors for Electric Powered Aircraft International conference

N. Hayakawa, H. Kamada, H. Kojima, N. Aruga, K. Utatsu, S. Watanabe

22nd IEEE International Conference on Dielectric Liquids 2023.6.27 IEEE DEIS

Event date： 2023.6

Language：English Presentation type：Oral presentation (general)

Venue：Worcester Country：United States

Higher power density motors for electric powered aircraft require higher voltage. The authors aim to apply a lubricating oil used for cooling motor windings to an insulating material to improve the dielectric strength of motors. In motor insulation, it is required to prevent the occurrence of partial discharge (PD) and understand the insulating characteristics of the lubricating oil. In this paper, we first measured and compared the breakdown voltage (BDV) of the lubricating oil and mineral oil in a fundamental sphere-sphere electrode system, and discussed the basic breakdown characteristics. The results suggest that the lubricating oil has superior dielectric characteristics to the mineral oil. Next, PD inception voltage (PDIV) of an arrow pair of enamel-coated rectangular wires in the lubricating oil was measured and compared with the estimated PDIV by electric field analysis. As a result, the measured PDIV was generally consistent with the estimated PDIV. Therefore, the lubricating oil insulation is expected to improve the dielectric strength in the motor windings for electric powered aircraft.

DOI： 10.1109/ICDL59152.2023.10209296

Scopus

CiNii Research

多端子直流送電システムの線路故障時における超電導限流器の限流効果および過渡安定度向上効果

村上雅紀，西澤大将，小島寛樹，早川直樹

令和5年電気学会全国大会 2023.3.17 電気学会

電子追跡シミュレーションによる真空中沿面放電の初期進展メカニズム

杉浦拓真，小島寛樹，早川直樹

令和5年電気学会全国大会 2023.3.16 電気学会

電動推進航空機用モータにおける流動潤滑油の部分放電開始特性

鎌田泰任，中澤尚輝，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

令和5年電気学会全国大会 2023.3.15 電気学会

コンデンサ形計器用変圧器におけるアルミ箔/油浸紙複合絶縁系の部分放電特性

林恭平，永木雄也，小島寛樹，吉田昌展，早川直樹

令和5年電気学会全国大会 2023.3.15 電気学会

真空中コンディショニングの放電電荷量依存性における電極初期表面状態の影響

北直樹，小島寛樹，福田英昭，山村健太，早川直樹

令和5年電気学会全国大会 2023.3.15 電気学会

真空中交流コンディショニングにおける粒子起因による多重絶縁破壊

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和5年電気学会全国大会 2023.3.15 電気学会

乾燥空気中におけるコーン型ε-FGMスペーサの絶縁破壊特性

加藤拓夢，杉本遼次，小島寛樹，柳瀬博雅，岡本健次，早川直樹

令和5年電気学会全国大会 2023.3.17 電気学会

コンデンサ形計器用変圧器の期待寿命評価方法および部分放電進展特性

永木雄也，林恭平，小島寛樹，吉田昌展，早川直樹

電気学会静止器研究会 2022.12.15 電気学会静止器技術委員会

Application of TEV Sensors to PD Measurement for Capacitor Voltage Transformers International conference

Y. Nagaki, H. Kojima, M. Yoshida, N. Hayakawa

9th International Conference on Condition Monitoring and Diagnosis 2022.11.16 IEEJ Technical Committee on Dielectrics and Electrical Insulation

Event date： 2022.11

Language：English Presentation type：Oral presentation (general)

Venue：Kitakyushu Country：Japan

This study aims to establish an insulation diagnosis method based on partial discharge (PD) measurement for capacitor voltage transformers (CVTs). Since aged CVTs over 50 years have been used in substations, an insulation diagnosis technique for CVTs is urgently required. Recently, transient earth voltage (TEV) sensors are used as PD detection sensors in transformers. Since the TEV sensors detect leakage electromagnetic waves and ground line currents, the PD signals in CVTs can also be detected by TEV sensors. However, the applicability of a TEV sensor to PD measurement in CVTs has not been verified. In this paper, the applicability of a TEV sensor for PD detection in the actual CVT (24-year-old) is discussed. As the experimental results, it was found that the TEV output has a good correlation with the PD charge over a wide range from 60 pC to 60,000 pC with the correlation coefficient as high as 0.99. Therefore, the TEV sensor is effective as a PD sensor for CVTs.

DOI： 10.23919/CMD54214.2022.9991361

Scopus

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Partial Discharge Characteristics of Aluminum Foil/Oil-impregnated Paper Insulation System for Insulation Diagnosis of Capacitor Voltage Transformers International conference

K. Hayashi, S. Wakita, Y. Nagaki, H. Kojima, M. Yoshida, N. Hayakawa

9th International Conference on Condition Monitoring and Diagnosis 2022.11.17 IEEJ Technical Committee on Dielectrics and Electrical Insulation

Event date： 2022.11

Language：English Presentation type：Poster presentation

Venue：Kitakyushu Country：Japan

Capacitor voltage transformers (CVTs) composed of aluminum foil/oil-impregnated paper insulation system have been operated over 30 years in substations. For the condition monitoring and diagnosis of aged CVTs, partial discharge (PD) detection is expected. However, PD characteristics from PD inception and progress to breakdown (BD) have not yet been clarified. Thus, PD characteristics of a fundamental insulation model composed of aluminum foil/oil-impregnated paper insulation systems are discussed in this paper. Experimental results under a fixed applied voltage revealed that PD characteristics can be classified into 3 periods. In Period 1, PD signals were intermittently generated mainly around the peak phase of applied voltage. In Period 2, PD signals were continuously generated around zero crossing (void discharge) to peak phase. In Period 3, PD signals larger than 10,000 pC were generated. Together with the above electrical PD measurement, the optical measurement of PD light emission images, bubble behavior, and their time transmission were also carried out in order to discuss the mechanism of PD progress.

DOI： 10.23919/CMD54214.2022.9991513

Scopus

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Discharge Developing Time of Surface Flashover on Solid Dielectrics around Impulse Test Voltage of Vacuum Interrupters International conference

R. Watarai, H. Kojima, T. Donen, S. Yamaguchi, N. Hayakawa

9th International Conference on Condition Monitoring and Diagnosis 2022.11.15 IEEJ Technical Committee on Dielectrics and Electrical Insulation

Event date： 2022.11

Language：English Presentation type：Poster presentation

Venue：Kitakyushu Country：Japan

We have found that the developing time Td of surface flashover on solid dielectrics (alumina) in vacuum is dominated by the propagation time of the conductive channel, which is proportional to the discharge path length and inversely proportional to the square of the discharge inception voltage Vd. Based on the experimental database on Td-Vd characteristics below 30 kV, we have proposed a non-optical diagnostic method for the discharge type and its path length of vacuum interrupters (VI). In this paper, we extend the Td-Vd characteristics up to 100 kV, which is close to the impulse test voltage of VI at 6.6 kV class. Experimental results for different experimental systems and electrode configurations have revealed that at low voltages (Vd < 30 kV), it is possible from the conventional Td-Vd characteristics to identify the flashover discharge path length regardless of the experimental system and electrode configuration. On the other hand, at high voltages (Vd > 40 kV), Td is longer than the expected value based on the conventional Td-Vd characteristics, which may be affected not only by the propagation time of the conductive channel but also by the propagation time of secondary electron avalanche and the developing time of gap discharge.

DOI： 10.23919/CMD54214.2022.9991358

Scopus

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異種材料対向電極の真空中コンディショニングにおける放電電荷量と対向電極材料付着の推移

北直樹，小島寛樹，福田英昭，山村健太，早川直樹

令和4年電気学会基礎・材料・共通部門大会 2022.9.13 電気学会基礎・材料・共通部門

真空中固体絶縁物上の沿面放電における放電進展時間の電圧依存性

渡會凌平，小島寛樹，道念大樹，山口信一，早川直樹

令和4年電気学会基礎・材料・共通部門大会 2022.9.13 電気学会基礎・材料・共通部門

コンデンサ形計器用変圧器のPD測定へのTEVセンサの適用

永木雄也，小島寛樹，吉田昌展，早川直樹

令和4年電気学会電力・エネルギー部門大会 2022.9.8 電気学会電力・エネルギー部門

多端子直流送電システムの超電導限流器配置に関する考察

村上雅紀，小島寛樹，早川直樹

令和四年度電気・電子・情報関係学会東海支部連合大会 2022.8.30 電気学会東海支部，電子情報通信学会東海支部，情報処理学会東海支部，照明学会東海支部，映像情報メディア学会東海支部，日本音響学会東海支部，IEEE名古屋支部

Temperature Rise on Permittivity and Conductivity Graded Materials (ε/σ-FGM) Spacer for HVDC GIS/GIL Invited

Rachmawati, H. Kojima, N. Hayakawa

2022.8.30

ε-FGMスペーサ沿面上に金属異物が付着した場合におけるSF6ガス中フラッシオーバ電圧

加藤英明，加藤拓夢，小島寛樹，蒲原聖也，保科好一，早川直樹

245kV級GIS用ε-FGMスペーサにおけるフラッシオーバ起点

加藤拓夢，小島寛樹，加藤克巳，大久保仁，足立和郎，岡本健次，早川直樹

陰極Cu-陽極SUS電極系の真空中コンディショニングによる絶縁耐圧向上効果

北直樹，小島寛樹，福田英昭，山村健太，早川直樹

コンデンサ形計器用変圧器におけるアルミ箔/油浸紙複合絶縁系の部分放電進展特性

林恭平，脇田周太，永木雄也，小島寛樹，吉田昌展，早川直樹

真空中固体絶縁物上の沿面放電開始に及ぼす帯電分布形状の影響

杉浦拓真，小島寛樹，早川直樹

令和四年度電気・電子・情報関係学会東海支部連合大会 2022.8.29 電気学会東海支部，電子情報通信学会東海支部，情報処理学会東海支部，照明学会東海支部，映像情報メディア学会東海支部，日本音響学会東海支部，IEEE名古屋支部

モンテカルロ法による真空中絶縁破壊後の金属蒸気拡散の推定

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

電動推進航空機用モータにおける流動潤滑油の絶縁破壊特性

鎌田泰任，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

大規模再生可能エネルギー導入とGIS Invited

小島寛樹

電気学会電力・エネルギーフォーラム「ガス絶縁開閉装置に要求されるIT化融合技術と再生可能エネルギー対応技術の動向」 2022.6.29 電気学会電力・エネルギー部門開閉保護技術委員会

Partial Discharge Progress and Breakdown Characteristics of Aluminum Foil/Oil-impregnated Paper Insulation System International conference

N. Hayakawa, S. Wakita, Y. Nagaki, M. Yoshida, H. Kojima

21st IEEE International Conference on Dielectric Liquids 2022.6.2 IEEE DEIS

Event date： 2022.5 - 2022.6

Language：English Presentation type：Poster presentation

Venue：Seville Country：Spain

Static capacitors (SC) and capacitor voltage transformers (CVT) operated over 30 years in substations are composed of aluminum foil/oil-impregnated paper insulation system. For the condition monitoring and diagnosis of aged SCs and CVTs, partial discharge (PD) measurement is expected. However, PD characteristics from PD inception and progress to breakdown (BD) are not yet clarified. Thus, in this paper, we carried out electrical and optical investigation of PD progress and BD characteristics of a fundamental insulation model composed of aluminum foil/oil-impregnated paper insulation system. As a result, we clarified that PD progress can be classified into 3 periods. In the Period 1, PD signals less than 500 pC were intermittently generated around the peak phase of applied AC voltage and dot-like PD light emission was observed at the edge of aluminum foil. In the Period 2, PD signals larger than 500 pC were continuously generated around zero crossing (void discharge) to peak phase and PD light emission was observed on the peripheries of the aluminum foil. In the Period 3, PD signals larger than 10,000 pC were generated with the extended PD light emission and bubbles, leading to BD through the oil-impregnated papers.

DOI： 10.1109/ICDL49583.2022.9830964

Scopus

Expected Lifetime Evaluation of Oil-impregnated Paper Capacitors International conference

M. Yoshida, Y. Nagaki, H. Kojima, N. Hayakawa

21st IEEE International Conference on Dielectric Liquids 2022.6.2 IEEE DEIS

Event date： 2022.5 - 2022.6

Language：English Presentation type：Poster presentation

Venue：Seville Country：Spain

This paper describes the concept of a method for evaluating the insulation lifetime for oil-impregnated paper capacitors in capacitor voltage transformers (CVTs), based on the short-term breakdown characteristics and partial discharge inception characteristics of aged oil-impregnated paper capacitors. In addition, the time margin (lead time) from the inception of partial discharge to breakdown at the operating electric field of CVT is evaluated.

DOI： 10.1109/ICDL49583.2022.9830938

Scopus

多端子直流送電システムにおける超電導限流器の限流効果および過渡安定度向上効果

村上雅紀，小島寛樹，早川直樹

令和4年電気学会全国大会 2022.3.22 電気学会

不平等電界下におけるCO2/N2混合ガス中絶縁破壊メカニズムの混合比依存性

尾﨑脩平，小島寛樹，早川直樹

令和4年電気学会全国大会 2022.3.23 電気学会

電動推進航空機用モータの高出力密度化に向けた潤滑油中コイルモデルの部分放電開始特性

鎌田泰任，脇田周太，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

令和4年電気学会全国大会 2022.3.21 電気学会

油浸紙コンデンサの期待寿命評価の検討

永木雄也，小島寛樹，吉田昌展，早川直樹

令和4年電気学会全国大会 2022.3.21 電気学会

アルミ箔/油浸紙複合絶縁系における絶縁破壊に至る部分放電特性の推移

脇田周太，林恭平，永木雄也，小島寛樹，吉田昌展，早川直樹

令和4年電気学会全国大会 2022.3.21 電気学会

放電開始条件を考慮したFGM絶縁スペーサの誘電率分布逆求解計算

加藤克巳，小島寛樹，早川直樹，増井秀好，柳瀬博雅，岡本健次，大久保仁

令和4年電気学会全国大会 2022.3.23 電気学会

実器サイズGIS用ε-FGMスペーサにおける絶縁破壊特性の理論的検討

加藤拓夢，小島寛樹，加藤克巳，大久保仁，足立和郎，岡本健次，早川直樹

令和4年電気学会全国大会 2022.3.23 電気学会

Discharge Inception Voltage Improvement by Application of Permittivity and Conductivity Graded Materials (ε/σ-FGM) to HVDC GIS Spacer

Rachmawati, H. Kojima, K. Kato, N. Hayakawa

The 2022 Annual Meeting of the Institute of Electrical Engineers of Japan 2022.3.23 Institute of Electrical Engineers of Japan

真空中コンディショニング飽和時の絶縁耐力に及ぼす放電電荷量と対向電極材料付着の影響

北直樹，小島寛樹，福田英昭，山村健太，早川直樹

令和4年電気学会全国大会 2022.3.21 電気学会

真空中高周波交流コンディショニングにおける多重絶縁破壊に関する考察

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和4年電気学会全国大会 2022.3.21 電気学会

異種材料が対向する電極の真空中コンディショニングにおける絶縁耐力と材料付着の放電電荷量依存性

北直樹，小島寛樹，福田英昭，山村健太，早川直樹

電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧合同研究会 2022.1.21 電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧技術委員会

CO2/N2混合ガス中におけるチャネル加熱絶縁破壊電圧

尾﨑脩平，小島寛樹，早川直樹

令和3年（2021年）放電学会年次大会 2021.12.3 放電学会

真空中固体絶縁物上における帯電分布形状が沿面放電電圧に与える影響

渡會凌平，小島寛樹，早川直樹

令和3年（2021年）放電学会年次大会 2021.12.3 放電学会

Flashover Voltage Estimation of Cone-type GIS Spacer with Permittivity Graded Materials (ε-FGM) by Volume-Time Theory in Consideration with Conductor Surface Roughness in SF₆ Gas Invited International conference

N. Hayakawa, Y. Miyazaki, H. Kojima, K. Kato, H. Okubo, K. Adachi, K. Okamoto

22nd International Symposium on High Voltage Engineering 2021.11.23 Xi'an Jiaotong University, State Key Laboratory of Electrical Insulation and Power Equipment, China Electrotechnical Society, Engineering Dielectrics Technical Committee, China Society for Electrical Engineering, Chinese National Committee of CIGRE, High Voltage Technical Committee and The International Council on Large Electric Systems

Event date： 2021.11

Language：English Presentation type：Oral presentation (invited, special)

Venue：Xi'an Country：China

Toward the compact gas insulated switchgears (GIS) and transmission lines (GIL), we have been investigating a novel electric field grading technique around the GIS spacer by “functionally graded materials (FGM)” with spatial distribution of permittivity (ε-FGM). We have already designed and fabricated the cone-type ε-FGM spacer samples with the relative permittivity distribution between 10 and 4 for 245 kV class GIS and obtained the higher flashover voltage (FOV) than that of the spacer samples with uniform permittivity. In this paper, in order to verify the estimated FOV of the ε-FGM spacer samples, we estimated the theoretical discharge inception voltage (TDIV50) by the analytical approach with the extended Volume-Time theory in consideration with the conductor surface roughness. The estimated TDIV50 of the ε-FGM spacer sample was verified to be consistent with the measured FOV and higher by 28 % in SF6 gas at 0.6 MPa-abs than that of the conventional spacer sample.

DOI： 10.1049/icp.2022.0260

Scopus

Time Transition of Gas Conductivity and Charge Behavior in SF6-Epoxy Composite Insulation System Under DC Partial Discharge International conference

R. Nakane, H. Kojima, N. Hayakawa

22nd International Symposium on High Voltage Engineering 2021.11.24 Xi'an Jiaotong University, State Key Laboratory of Electrical Insulation and Power Equipment, China Electrotechnical Society, Engineering Dielectrics Technical Committee, China Society for Electrical Engineering, Chinese National Committee of CIGRE, High Voltage Technical Committee and The International Council on Large Electric Systems

Event date： 2021.11

Language：English Presentation type：Poster presentation

Venue：Xi'an Country：China

The charge accumulation at the interface between gas medium and solids in DC gas insulated switchgear (DC-GIS) and DC gas insulated line (DC-GIL) is crucial in their electrical insulation design and operation. In this paper, the charging process on solid insulator surface under DC partial discharge (DC-PD) in SF6 gas is reported. A needle-epoxy plane electrode system is installed in SF6 gas at atmospheric pressure. The measured surface potential distribution on epoxy plate is compared with the simulation considering charge behavior in SF6 gas such as ion generation due to DC-PD, drift and diffusion. As a result, we quantitatively clarify the charge accumulation process under DC-PD as the main source of charge carrier in terms of the activated conductivity distribution in SF6 gas. The charging process under DC-PD is attributed to the time transition of activated conductivity distribution in SF6 gas gap, which is approximately 1010 times higher than that in non-activated conductivity space. This means that the activated conductivity distribution in SF6 gas is the crucial parameter that determines the charging process for DC-GIS/GIL under DC-PD occurrence.

DOI： 10.1049/icp.2022.0474

Scopus

Application of SiC-filled Permittivity and Conductivity Graded Material (ε/σ-FGM) in HVDC GIS Spacer International coauthorship International conference

Rachmawati, H. Kojima, K. Kato, N. Zebouchi, N. Hayakawa

Event date： 2021.11

Language：English Presentation type：Oral presentation (general)

Venue：Xi'an Country：China

The size reduction of HVDC GIS is needed for reduction of SF6 gas use. The challenge concerning the insulating material in HVDC GIS is to reduce the high electric field strength in gas around the solid insulators (spacers). Our previous works have shown the effectiveness of the functionally graded material (FGM) with graded permittivity (ε) and conductivity (σ) in controlling the high electric field strength under various DC operating conditions. However, ε/σ distributions were independent of each other. For practical implementation of FGM to HVDC GIS, the flexible mixture casting (FMC) method so far allows us to create a material whose ε/σ distributions are interdependent. In this paper, based on the measured dependence between ε and σ in SiC-filled epoxy composites, the electric field relaxation effect is evaluated under three different ε/σ distributions (U-type, grading-to-higher conductivity (GHC)-type and grading-to-lower conductivity (GLC)-type) applied to a 320 kV HVDC GIS spacer model. The results show that GLC-type ε/σ-FGM has effectively and constantly reduced the maximum electric field strength under the time-varying voltage application from DC-on to DC-steady state and against temperature differences between the high voltage and ground sides up to 70 K.

DOI： 10.1049/icp.2022.0264

Scopus

Inverse Analysis of Optimum Permittivity Distribution for FGM Spacer in Consideration with Multiple Objective Functions in Gaseous Insulation System International conference

K. Kato, H. Kojima, N. Hayakawa, H. Masui, H. Yanase, K. Okamoto, H. Okubo

Event date： 2021.11

Language：English Presentation type：Poster presentation

Venue：Xi'an Country：China

For relaxation of electric field (E-field) stress around solid insulation spacer in HV-GIS (Gas Insulated Switchgears), we have proved the effectiveness of an application of functionally graded materials (FGM) with spatial distribution of permittivity (ε-FGM). For this purpose, we have proposed a technique for inverse analysis of the permittivity distribution in an ε-FGM spacer. The technique can provide us optimum permittivity distribution with the maximum E-field stress relaxation with less computation time. In this paper, we developed the new technique of the inverse analysis under the consideration of multiple objective functions on the insulation performances. In our study, we focus on three kinds of functions: (a) dielectric strength in SF6 gas gap, (b) dielectric strength on the spacer surface, and (c) dielectric strength on the embedded electrode/epoxy spacer interface. Under the consideration of three objective functions, the optimum permittivity distribution in ε-FGM spacer are modified full-automatically. Through the application results to GIS spacer, we obtain the inverse analysis of optimum permittivity distribution by only 11 times of iterations. As a result, we obtained 25% improvement of insulation performance around ε-FGM spacer compared with the conventional spacer with uniform permittivity distribution.

DOI： 10.1049/icp.2022.0245

Scopus

Discrimination of Discharge Pattern in Cut Model of Vacuum Interrupter International conference

H. Kojima, T. Donen, T. Kimura, K. Kokura, N. Hayakawa

29th International Symposium on Discharges and Electrical Insulation in Vacuum 2021.9.28 Consorzio RFX

Event date： 2021.9

Language：English Presentation type：Oral presentation (general)

Venue：Padova Country：Italy

Electrical insulation of a vacuum interrupter (VI) is a composite system composed of vacuum, metal, and solid insulator. Detection of weak points in insulation is important for insulation design of VI. However, solid insulators of VI are mostly made of opaque ceramics, and it is very difficult to directly visually observe discharge sites and patterns inside VI. Previously, we have proposed a discrimination method of discharge patterns in VI by extracting features of applied voltage, discharge current, and shield potential change. In this study, we aim to verify that our proposing method can be applied to an actual structure of VI. We prepared a cut model of VI, whose shield electrode and alumina ceramic insulators have been partly cut for observing the discharge site. In this VI cut model, we simulated the weak points in insulation by additional needle electrodes. We applied a negative standard lightning impulse voltage between contact electrodes, and measured the applied voltage, the shield potential, and the anode current. In various settings, we almost succeeded to discriminate the initiation pattern of discharge, even in the case of complex discharge pattern with gap and/or surface discharge. In this verification, we found the new discharge pattern, in which the first gap discharge induced another gap discharge due to the diffusion of particles from the first discharge. However, by modifying the discrimination method based on the above physical mechanism of new discharge pattern, we got the prospects that the method can be applied to actual VI structure.

DOI： 10.1109/ISDEIV46977.2021.9586961

Scopus

Anode Material Adhesion to Cathode during Spark Conditioning Process in Vacuum International conference

N. Kita, H. Kojima, H. Fukuda, M. Sakaki, N. Hayakawa

29th International Symposium on Discharges and Electrical Insulation in Vacuum 2021.9.27 Consorzio RFX

Event date： 2021.9

Language：English Presentation type：Poster presentation

Venue：Padova Country：Italy

Spark conditioning is an effective method to improve electrical insulation strength of vacuum circuit breakers. In the conditioning process, defects on cathode surface are removed by repetitive breakdowns (BDs). However, we have elucidated that at the same time, micro-protrusions can be generated on the cathode surface by the adhesion of melted particles of anode material. In this paper, we discuss the relationship between the anode material adhesion to cathode and the conditioning saturation from an experimental approach. We set rod-plane electrodes made of Cu and stainless steel (SUS) in a vacuum chamber. We conduct spark conditioning by repetitive impulse voltages for several pairs of Cu and SUS electrodes. To one pair, the voltage is applied until the conditioning saturation. To the others, the smaller number of voltages before conditioning saturation is applied. After that, we observe the surface of rod cathodes with a digital microscope. As a result, we observe protrusion-like adhesion of the anode material to the cathode surface after conditioning saturation. On the other hand, we confirm coat-like adhesion of the anode material to the cathode surface before conditioning saturation. From these results, it is considered that coat-like adhesion mainly occur up to the saturation voltage, and then protrusion-like adhesion occur due to BD at the saturation voltage level. In other words, the generation of micro-protrusions can be a dominant factor of conditioning saturation process in vacuum.

DOI： 10.1109/ISDEIV46977.2021.9586907

Scopus

Dielectric Strength Improvement by Higher Frequency AC Conditioning International conference

R. Konagi, H. Kojima, S. Iitsuka, M. Kobayashi, N. Hayakawa

29th International Symposium on Discharges and Electrical Insulation in Vacuum 2021.9.28 Consorzio RFX

Event date： 2021.9

Language：English Presentation type：Oral presentation (general)

Venue：Padova Country：Italy

We discuss the effects of AC conditioning with higher frequency on the dielectric strength in vacuum. We have confirmed that multiple breakdowns occur in a half cycle of AC voltage application in the AC conditioning process. It is considered that the multiple breakdowns are triggered by metal vapor due to the previous breakdown in the same half cycle. Such breakdowns can not be attributed to a micro protrusion on the electrode surface. Therefore, multiple breakdowns are considered not effective, but harmful for conditioning. In this paper, we carried out the AC conditioning with the higher frequency than the commercial power frequency in the sphere-plane electrode system. We experimentally confirmed that the conditioning effect is improved by increasing the frequency of AC conditioning in the sphere-plane electrode system, where multiple or harmful breakdowns were suppressed during AC conditioning. These results suggest the feasibility of higher frequency AC conditioning for the dielectric strength improvement in vacuum.

DOI： 10.1109/ISDEIV46977.2021.9586929

Scopus

アルミ箔/油浸紙複合絶縁系における部分放電開始・進展・絶縁破壊特性

脇田周太，永木雄也，小島寛樹，吉田昌展，早川直樹

第52回電気電子絶縁材料システムシンポジウム 2021.9.14 電気学会誘電・絶縁材料技術委員会

Theoretical Investigation on Discharge Inception Voltage Improvement of SiC-filled Permittivity and Conductivity Graded Material (ε/σ-FGM) for HVDC GIS International coauthorship

Rachmawati, H. Kojima, K. Kato, N. Zebouchi, N. Hayakawa

52nd Symposium on Electrical and Electronic Insulating Materials and Applications in Systems 2021.9.14 IEEJ Technical Committee on Dielectrics and Electrical Insulation

電動推進航空機用モータにおける潤滑油絶縁の適用可能性

鎌田泰任，脇田周太，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

第52回電気電子絶縁材料システムシンポジウム 2021.9.14 電気学会誘電・絶縁材料技術委員会

X線CTを用いた誘電率傾斜機能材料（ε-FGM）の誘電率分布測定

加藤拓夢，小島寛樹，柳瀬博雅，岡本健次，早川直樹

令和三年度電気・電子・情報関係学会東海支部連合大会 2021.9.8 電気学会東海支部，電子情報通信学会東海支部，情報処理学会東海支部，照明学会東海支部，映像情報メディア学会東海支部，日本音響学会東海支部，IEEE名古屋支部

真空中におけるコンディショニングと放電電荷量の相関

北直樹，小島寛樹，福田英昭，榊正幸，早川直樹

令和三年度電気・電子・情報関係学会東海支部連合大会 2021.9.7 電気学会東海支部，電子情報通信学会東海支部，情報処理学会東海支部，照明学会東海支部，映像情報メディア学会東海支部，日本音響学会東海支部，IEEE名古屋支部

真空中高周波交流コンディショニングにおける放電の電子温度

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

アルミ箔/油浸紙複合絶縁系における部分放電発光の電圧依存性

脇田周太，永木雄也，小島寛樹，吉田昌展，早川直樹

電動推進航空機用モータに向けた潤滑油の絶縁破壊基礎特性

鎌田泰任，脇田周太，小島寛樹，有賀信雄，卯辰清志，渡邉瞬也，早川直樹

CO₂/N₂混合ガス中におけるチャネル加熱絶縁破壊発生電圧

尾﨑脩平，小島寛樹，早川直樹

真空中固体絶縁物上における帯電分布形状が沿面放電電圧に与える影響

渡會凌平，小島寛樹，早川直樹

Discharge Inception Voltage Calculation of HVDC GIS with Graded Permittivity and Conductivity (ε/σ-FGM) Spacer

Rachmawati, H. Kojima, K. Kato, N. Hayakawa

2021 Tokai-Section Joint Conference on Electrical, Electronics, Information, and Related Engineering 2021.9.8

真空中高周波交流コンディショニングによる耐圧向上効果～放電発光スペクトルからみた考察～

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和3年電気学会基礎・材料・共通部門大会 2021.9.3 電気学会基礎・材料・共通部門

誘電率傾斜機能材料（ε-FGM）における誘電率分布の非破壊測定

加藤拓夢，小島寛樹，柳瀬博雅，岡本健次，早川直樹

令和3年電気学会基礎・材料・共通部門大会 2021.9.3 電気学会基礎・材料・共通部門

真空中におけるコンディショニング過程で生成する微小突起サイズ

北直樹，小島寛樹，福田英昭，榊正幸，早川直樹

令和3年電気学会電力・エネルギー部門大会 2021.8.26 電気学会電力・エネルギー部門

真空中コンディショニングの飽和過程における対向電極材料の付着

北直樹，小島寛樹，福田英昭，榊正幸，早川直樹

令和3年電気学会全国大会 2021.3.10 電気学会

真空中高周波交流コンディショニングにおける多重絶縁破壊の抑制による耐圧向上効果

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和3年電気学会全国大会 2021.3.10 電気学会

Electric Field Grading on HVDC GIS Spacer by SiC-filled Permittivity and Conductivity Graded Material (ε/σ-FGM)

Rachmawati, H. Kojima, K. Kato, N. Hayakawa

The 2021 Annual Meeting of the Institute of Electrical Engineers of Japan 2021.3.11 IEEJ

SF6ガス中FGM絶縁スペーサの最適絶縁性能を目指した誘電率分布逆求解技術

加藤克巳，小島寛樹，早川直樹，増井秀好，柳瀬博雅，岡本健次，大久保仁

令和3年電気学会全国大会 2021.3.11 電気学会

超電導パンケーキコイルの対地絶縁モデルにおける液体窒素の動的絶縁破壊特性

森優次，村上雅紀，小島寛樹，早川直樹

令和3年電気学会全国大会 2021.3.11 電気学会

アルミ箔/油浸紙複合絶縁系における部分放電および絶縁破壊特性

脇田周太，小島寛樹，吉田昌展，早川直樹

令和3年電気学会全国大会 2021.3.9

SF6ガス/エポキシ複合絶縁系の直流部分放電下におけるガス中導電率分布の時間推移

中根龍一，小島寛樹，早川直樹

令和3年電気学会全国大会 2021.3.11

繰り返しサージ電圧下のエナメル線の部分放電開始電圧における湿度および気圧依存性

林亮平，小島寛樹，早川直樹

令和3年電気学会全国大会 2021.3.11 電気学会

Diagnosis of Discharge Pattern in Vacuum Interrupter by Shield Potential Measurement International conference

H. Kojima, T. Donen, T. Kimura, N. Hayakawa

8th International Conference on Condition Monitoring and Diagnosis 2020.10.28 Department of Electrical Engineering, Faculty of Engineering, King Mongkut's Institute of Technology Ladkrabang

Event date： 2020.10

Language：English Presentation type：Oral presentation (general)

Venue：King Mongkut's Institute of Technology Ladkrabang Country：Thailand

In vacuum discharge, we found that the discharge developing time depends only upon the discharge path length in the case of gap discharge, whereas it is in inverse proportion to the square of the discharge inception voltage in the case of surface flashover. Based on the database for fundamental electrode configuration, we have proposed a diagnosing method of discharge pattern in vacuum interrupter (VI). In this paper, we applied the diagnosing method to an actual VI model and verified the effectiveness of the method. We measured the applied voltage and the shield potential with voltage dividers and the discharge current with high-frequency current transformer. We also captured the still image of discharge by a digital camera to verify the discharge path in the VI model with an observation aperture. By changing the electrode configuration in the VI model, we observed the various discharge patterns, e.g. the gap discharge between contacts, the surface flashover on the solid insulator through the shield, and the combination of them. Experimental results revealed that we succeeded in diagnosing the discharge pattern with the validity higher than 90%.

DOI： 10.1109/CMD48350.2020.9287205

Scopus

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Pressure Dependence of Quench-induced Dynamic Breakdown Characteristics of HTS Pancake Coil Model for Resistive SFCL International conference

N. Hayakawa, Y. Mori, H. Kojima

Applied Superconductivity Conference 2020 2020.11.4

Dielectric Characteristics of Liquid Nitrogen / Synthetic Paper Composite Insulation System for Extra High Voltage HTS Cable International conference

N. Hayakawa, K. Yamakami, T. Masuda, H. Kojima

Applied Superconductivity Conference 2020 2020.11.3

Time Transition of Conductivity Distribution in Air by DC Partial Discharge for Air-solid Composite Insulation Systems International conference

R. Nakane, H. Kojima, J. Suehiro, H. Okubo, N. Hayakawa

IEEE Conference on Electrical Insulation and Dielectric Phenomena 2020 2020.10.20 IEEE DEIS

Event date： 2020.10

Language：English Presentation type：Poster presentation

Venue：virtual conference Country：United States

Toward the development of HVDC power apparatus, we investigate the charging process on solid insulator in terms of the time transition of conductivity distribution in air for air-solid composite insulation system from DC-on to DC steady-state. By using needle-air-PMMA-plane electrode configuration, we measure the time evolution of surface potential on PMMA due to partial discharge at the needle tip under negative DC voltage. We compare the measured surface potential distribution with the simulation result considering the charge behavior in air. Especially, a novel simulation model considering the charge supply due to DC partial discharge is built. As a result, in air-solid composite insulation system under negative DC application, the time transition of conductivity distribution in air corresponding to the charge accumulation is evaluated quantitatively.

DOI： 10.1109/CEIDP49254.2020.9437492

Scopus

電力機器内部アーク発生時の高温ガスによる周囲への熱的影響解析

神足将司，岩田幹正，田所兼，田中慎一，小島寛樹，早川直樹

電気学会放電・プラズマ・パルスパワー/静止器/開閉保護合同研究会 2020.9.28 電気学会放電・プラズマ・パルスパワー/静止器/開閉保護技術委員会

Breakdown Characteristics of Cone-type ε-FGM Spacer for Gas Insulated Switchgears International conference

Y. Miyazaki, A. Izu, Z. Liang, H. Kojima, H. Masui, H. Mitsudome, H. Yanase, K. Okamoto, K. Watanabe, K. Kato, N. Hayakawa

9th International Symposium on Electrical Insulating Materials 2020.9.14 IEEJ Technical Committee on Dielectrics and Electrical Insulation

Event date： 2020.9

Language：English

Venue：virtual web conference Country：Japan

For the downsizing of gas insulated switchgears (GIS), a novel electric field grading technique is highly expected. In order to meet this demand, we have been investigating the electric field control and relaxation technique by "functionally graded materials" with the spatial distribution of permittivity (e-FGM). In this paper, we fabricated the 1/4-sized cone-type e-FGM spacer for 245 kV-class GIS and verified its breakdown voltage improvement effect by both experiment and simulation.

Scopus

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Electric Field Grading by Permittivity and Conductivity Graded Materials (ε/σ-FGM) for HVDC Gas Insulated Power Apparatus International coauthorship International conference

Rachmawati, A. Izu, R. Nakane, H. Kojima, K. Kato, N. Zebouchi, N. Hayakawa

9th International Symposium on Electrical Insulating Materials 2020.9.14 IEEJ Technical Committee on Dielectrics and Electrical Insulation

Event date： 2020.9

Language：English

Venue：virtual web conference Country：Japan

The progressive development of HVDC transmission system has urged us to develop a novel technique in supporting the performance of DC power apparatus. Functionally Graded Materials (FGM) are one of the techniques that allows us to control the electric field within the DC insulation system. Our previous work has reported that FGM with spatial conductivity distribution applied to a 320 kV DC-GIS spacer could reduce the maximum electric field under DC steady state condition. This paper investigates the applicability of the combination of spatial permittivity and conductivity graded materials (e/s-FGM) in DC power apparatus. ? / S - F G M are revealed to be more effective in suppressing maximum electric field as well as more uniformly distributed electric field against the increase of temperature distribution under polarity reversal, DC-on, and impulse superimposed on DC condition.

Scopus

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Conductivity Distribution in Air by Charging Process on Solid Dielectrics under DC Voltage International conference

R. Nakane, H. Kojima, N. Hayakawa, H. Okubo

9th International Symposium on Electrical Insulating Materials 2020.9.14 IEEJ Technical Committee on Dielectrics and Electrical Insulation

Event date： 2020.9

Language：English

Venue：virtual web conference Country：Japan

The enhancement of DC electrical insulation performance is required for the reliable HVDC power equipment and bulk power transmission in recent years. In this paper, we measure the charging process on PMMA in air under DC steady-state and investigate the space distribution of the conductivity in air by using needle-air-PMMA-plane electrode configuration. In order to sfmulate the space distribution of the conductivity in air under DC steady-state, the charge transport equations in air considering the generation, recombination and motion of positive and negative ions are solved. We calculate the space distribution of the conductivity in air activated by partial discharge. As a result, it is quantitatively estimated that highly conductive area in air with approximately 106 times higher conductivity than the other area is formed along the electric line of force from the needle electrode tip as the source of charge carrier.

Scopus

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Carbonization Phenomena Dependence on Pressure between Insulation Sheets by Steeper Inverter Surge at Inverter Fed Motor International conference

Y. Yoshitake, H. Kojima, Y. Kasai, S. Maruyama, H. Kojima, N, Hayakawa

9th International Symposium on Electrical Insulating Materials 2020.9.14 IEEJ Technical Committee on Dielectrics and Electrical Insulation

Event date： 2020.9

Language：English

Venue：virtual web conference Country：Japan

Recently, "carbonization phenomena on the insulation sheets" were newly detected as the unique precursor phenomena to the burning of the insulation of inverter-fed motors due to leakage current through the insulation system. We have previously studied the generation condition for the high dV/dt resulting in an inverter surge. In this study, we built an experimental setup based on an elemental model to simulate a steep surge voltages in the inverter and constructed the stator insulation inside the motor core to control the pressure between the insulation sheets. This paper reports the carbonization characteristics and the insulation design to prevent the carbonization caused by steep inverter surges.

Scopus

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真空中コンディショニング過程で生成される微小突起サイズ

北直樹，近藤史規，小島寛樹，福田英昭，榊正幸，早川直樹

令和2年電気学会電力・エネルギー部門大会 2020.9.11

超電導限流器の動的絶縁破壊特性における体積効果

森優次，小島寛樹，早川直樹

令和2年電気学会電力・エネルギー部門大会 2020.9.11

実機サイズGISスペーサへのε-FGM（誘電率傾斜機能材料）の適用

宮崎勇作，小島寛樹，早川直樹，加藤克巳，匹田政幸，大久保仁，渡辺桂司，岡本健次，足立和郎

令和2年電気学会電力・エネルギー部門大会 2020.9.10

ツイストペアの誘電損失によるエナメル皮膜温度上昇

林亮平，梶武文，小島寛樹，早川直樹

令和2年度電気・電子・情報関係学会東海支部連合大会

Electric Field Grading by Permittivity and Conductivity Graded Material (ε/σ-FGM) at Polarity Reversal for HVDC GIS

Rachmawati, H. Kojima, K. Kato, N. Hayakawa

超電導パンケーキコイルモデルにおける液体窒素の動的絶縁破壊電界の体積効果および熱流束依存性

森優次，小島寛樹，早川直樹

令和2年度電気・電子・情報関係学会東海支部連合大会

導電率傾斜機能材料（σ-FGM）のコーン型GISスペーサへの適用効果

梁照源，宮崎勇作，小島寛樹，加藤克巳，増井秀好，満留博，柳瀬博雅，岡本健次，早川直樹

令和2年度電気・電子・情報関係学会東海支部連合大会

可変配合注型法によるε-FGM（誘電率傾斜機能材料）を適用した実器サイズGISスペーサの誘電率分布測定

宮崎勇作，小島寛樹，早川直樹，今井隆浩，染谷竜太，保科好一

令和2年度電気・電子・情報関係学会東海支部連合大会

油浸紙絶縁における部分放電検出センサの感度比較

脇田周太，小島寛樹，吉田昌展，早川直樹

令和2年度電気・電子・情報関係学会東海支部連合大会

真空中高周波交流コンディショニングによる耐圧向上効果

小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和2年度電気・電子・情報関係学会東海支部連合大会

真空中コンディショニング過程における陰極への陽極材料の付着が飽和電圧に与える影響

北直樹，小島寛樹，福田英昭，榊正幸，早川直樹

令和2年度電気・電子・情報関係学会東海支部連合大会

直流部分放電下の空気/固体複合絶縁系における空気中導電率分布の推移過程

中根龍一，小島寛樹，大久保仁，早川直樹

令和2年度電気・電子・情報関係学会東海支部連合大会

誘電率傾斜機能材料（ε-FGM）を用いたGISスペーサモデルの作製とSF₆ガス中絶縁破壊電圧の理論的推定 Invited

宮路仁崇，小島寛樹，加藤克巳，早川直樹

令和2年電気学会基礎・材料・共通部門大会

空気/固体複合絶縁系の直流印加時における空気中導電率の時間推移

中根龍一，小島寛樹，大久保仁，早川直樹

令和2年電気学会基礎・材料・共通部門大会

真空中沿面放電における初期帯電迂回条件

西田歩成，小名木良太，小島寛樹，飯塚伸介，小林将人，早川直樹

令和2年電気学会全国大会

空気/固体複合絶縁系の直流定常状態における空気中導電率の空間分布

中根龍一，小島寛樹，早川直樹，大久保仁

令和2年電気学会全国大会

真空中交流部分放電による帯電形成時における固体絶縁物上の二次電子放出係数の時間推移

大木駿士朗，小島寛樹，竪山智博，浅利直紀，佐々木良輔，早川直樹

令和2年電気学会全国大会

空気中チャネル加熱絶縁破壊における電流増加および高導電率領域進展過程

浅野竜大，小島寛樹，早川直樹

令和2年電気学会全国大会

真空中コンディショニング過程における対向電極材料の付着

北直樹，近藤史規，小島寛樹，福田英昭，榊正幸，早川直樹

令和2年電気学会全国大会

真空中コンディショニングにおける陽極めっきの損耗

近藤史規，北直樹，小島寛樹，鈴木飛鳥，小橋眞，福田英昭，榊正幸，早川直樹

令和2年電気学会全国大会

ガス絶縁開閉装置向けコーン型ε-FGM（誘電率傾斜機能材料）スペーサの絶縁破壊特性

宮崎勇作，伊豆淳宏，梁照源，小島寛樹，満留博，柳瀬博雅，岡本健次，渡辺桂司，加藤克巳，早川直樹

令和2年電気学会全国大会

導電率の温度・電界依存性を考慮した傾斜機能材料の直流ガス絶縁電力機器への適用効果

伊豆淳宏，Rachmawati，中根龍一，小島寛樹，加藤克巳，早川直樹

令和2年電気学会全国大会

超高圧超電導ケーブルに向けた低誘電損失合成紙の電気絶縁特性

山上浩輝，脇田周太，小島寛樹，増田孝人，早川直樹

令和2年電気学会全国大会

超電導パンケーキコイルモデルにおける液体窒素の動的絶縁破壊特性の圧力依存性

森優次，山上浩輝，小島寛樹，早川直樹

令和2年電気学会全国大会

可変配合注型法による誘電率傾斜絶縁スペーサの樹脂分布可視化

染谷竜太，保科好一，今井隆浩，小島寛樹，早川直樹

令和2年電気学会全国大会

ツイストペアサンプルの部分放電開始電圧におけるエナメル皮膜の温度上昇

林亮平，梶武文，小島寛樹，早川直樹

令和2年電気学会全国大会

空気中チャネル加熱絶縁破壊における温度・電流上昇過程

浅野竜大，小島寛樹，早川直樹

電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧合同研究会 2020.1.24 電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧技術委員会

超高圧超電導ケーブルに向けた液体窒素/合成紙複合絶縁系における部分放電開始特性

山上浩輝，小島寛樹，増田孝人，早川直樹

電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧合同研究会 2020.1.25 電気学会誘電・絶縁材料/放電・プラズマ・パルスパワー/高電圧技術委員会

真空インタラプタ開口モデルによる複合的な放電経路に対する診断手法の検証

小島寛樹，道念大樹，木村俊則，小倉健太郎，早川直樹

電気学会放電・プラズマ・パルスパワー/開閉保護/高電圧合同研究会 2019.12.6 電気学会放電・プラズマ・パルスパワー/開閉保護/高電圧技術委員会

Analysis of the Characteristics of Pressure Rise and Exhausted Hot Gas due to Internal Arc Faults in SF₆-Insulated Power Equipment International conference

M. Kotari, T. Tadokoro, S. Tanaka, M. Iwata, H. Kojima, N. Hayakawa

2019 5th International Conference on Electric Power Equipment - Switching Technology 2019.10.15 Nagoya University

Event date： 2019.10

Language：English Presentation type：Oral presentation (general)

Venue：Kitakyushu Country：Japan

From an environmental perspective, when performing internal arc tests on SF6-insulated power equipment, SF6 may be replaced with air in accordance with the International Electrotechnical Commission standard. To develop an alternative method for internal arc testing in SF6-insulated power equipment, a specific procedure must be proposed to replace SF6 with air and select appropriate test parameters. Therefore, we have systematically obtained the experimental and analytical data of air and SF6 arcs to calculate the pressure rise in electric power equipment and the thermal effect of hot gas on the surroundings. The modeling of SF6-air and air-air flows is implemented using computational fluid dynamics to analyze the characteristics of pressure rise and exhausted hot gas due to internal arc faults in SF6-insulated power equipment.

DOI： 10.1109/ICEPE-ST.2019.8928689

Scopus

Suppression of Conditioning Effect in Vacuum by Micro-protrusions from Anode International conference

F. Kondo, H. Kojima, H. Fukuda, M. Sakaki, N. Hayakawa

2019 5th International Conference on Electric Power Equipment - Switching Technology 2019.10.14 Nagoya University

Event date： 2019.10

Language：English Presentation type：Oral presentation (general)

Venue：Kitakyushu Country：Japan

Spark conditioning is an effective method to improve electrical insulation strength of vacuum circuit breakers. We discuss the spark conditioning process in consideration of the generation of micro-protrusions on cathode surface by breakdown. We conducted the spark conditioning on three pairs of rod-plane electrodes made of OFHC Cu. For one pair, the voltages were applied until conditioning saturation, namely 600 times voltage applications. For the others, a smaller number of voltage applications (100 times and 300 times) before conditioning saturation were given. After these conditioning experiments, we observed the surface of rod cathodes with a microscope. After the conditioning by about 600 times voltage applications, many micro-protrusions appeared on the cathode surface. Some of them had a diameter larger than 20 m. They would be caused by adhesion of metallic particles from anode and remained through the conditioning process. On the other hand, few micro-protrusions were found on the cathodes with 100 and 300 times voltage applications. This means that the micro-protrusions were generated at the last period of the conditioning process. In other words, the generation of micro-protrusions can be a dominant factor of suppression and saturation of conditioning effect.

DOI： 10.1109/ICEPE-ST.2019.8928772

Scopus

誘電率/導電率傾斜機能材料を用いた直流ガス絶縁電力機器のインパルス重畳時における電界制御効果

伊豆淳宏，中根龍一，小島寛樹，加藤克巳，早川直樹

第50回電気電子絶縁材料システムシンポジウム

インバータサージ高峻度化により発生するカーボン遊離現象の検討

吉武勇一郎，小島啓明，笠井友樹，丸山正一，小島寛樹，早川直樹

第50回電気電子絶縁材料システムシンポジウム

誘電率傾斜機能材料（ε-FGM）を用いたコーン型絶縁スペーサの絶縁破壊特性

宮崎勇作，伊豆淳宏，小島寛樹，満留博，柳瀬博雅，岡本健次，渡辺桂司，加藤克巳，早川直樹

第50回電気電子絶縁材料システムシンポジウム

IEEE 14母線モデルにおける複数の超電導限流器の限流協調

森優次，小島寛樹，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

直流電界下の空気/固体複合絶縁系における空気中導電率の空間分布

中根龍一，小島寛樹，早川直樹，大久保仁

令和元年度電気・電子・情報関係学会東海支部連合大会

エナメル皮膜の誘電損失を考慮した部分放電開始電圧の繰り返し周波数依存性

林亮平，梶武文，小島寛樹，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

加圧空気中1次/2次ストリーマの絶縁破壊抑制/促進作用

浅野竜大，小島寛樹，米須大吾，額賀淳，六戸敏昭，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

真空中交流部分放電による固体絶縁物上の帯電進展特性の推移

大木駿士朗，小島寛樹，竪山智博，浅利直紀，佐々木良輔，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

真空中初期帯電存在時における陰極先端電界と沿面放電進展経路

西田歩成，小島寛樹，飯塚伸介，小林将人，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

真空中スパークコンディショニング過程における突起生成と飽和

近藤史規，小島寛樹，福田英昭，榊正幸，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

誘電率/導電率傾斜機能材料（ε/σ-FGM）の作製と放電開始電圧向上効果の検証

宮崎勇作，小島寛樹，加藤克巳，満留博，柳瀬博雅，岡本健次，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

直流高電圧印加時における傾斜機能材料の電界緩和の時間依存性

伊豆淳宏，中根龍一，小島寛樹，加藤克巳，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

超高圧超電導ケーブルに向けたTyvek^®/PE/Tyvek^®およびPPLP^®の電気絶縁特性の圧力依存性

山上浩輝，小島寛樹，増田孝人，早川直樹

令和元年度電気・電子・情報関係学会東海支部連合大会

FGM絶縁スペーサの誘電率逆求解自動計算技術の開発とその検証

加藤克巳，小島寛樹，早川直樹，満留博，柳瀬博雅，岡本健次，大久保仁

令和元年電気学会電力・エネルギー部門大会

Fault Current Limitation Coordination of Multiple SFCLs in IEEE 14-Bus System International conference

N. Hayakawa, Y. Mori, H. Kojima

14th European Conference on Applied Superconductivity

Quench-induced Breakdown Characteristics of HTS Pancake Coil for Resistive SFCL International conference

N. Hayakawa, M. Mimbu, H. Kojima, S. Isojima, M. Kuwata

14th European Conference on Applied Superconductivity

Inverse Analysis of Permittivity Distribution of FGM (Functionally Graded Materials) Insulator in Gaseous Insulation System International conference

K. Kato, H. Kojima, N. Hayakawa, H. Mitsudome, H. Yanase, K. Okamoto, H. Okubo

21st International Symposium on High Voltage Engineering

Modeling of Channel Heating Breakdown in Dry Air International conference

H. Kojima, R. Asano, D. Komesu, J. Nukaga, T. Rokunohe, N. Hayakawa

21st International Symposium on High Voltage Engineering 2019.8.27 Budapest University of Technology

Event date： 2019.8

Language：English Presentation type：Poster presentation

Venue：Budapest Country：Hungary

In dry air with a relatively short gap length under non-uniform electric field, the channel heating breakdown mechanism becomes critical to the electrical insulation design of power apparatus. We have experimentally clarified that the input energy density into the discharge channel almost decides the occurrence of channel heating breakdown in dry air. This implies that the rise of the channel temperature due to Joule heating causes the rise of the channel conductivity and the current, leading to the breakdown. In this paper, we construct the discharge channel heating model by the resistance circuits in consideration of the temperature dependence of conductivity and the shape of discharge channel, and investigate the process leading to the channel heating breakdown in dry air. The electrode system in this model is needle-plane electrodes with the gap length of 15 mm based on our experiments. At first, we verified that the process of channel heating breakdown can be explained by the temperature dependence of conductivity by using the preliminary zero-dimensional model with uniform temperature distribution in the discharge channel. With the given applied voltage and initial temperature, the temporal evolution of current and conductivity was calculated. Calculation results revealed that the temporal evolution of conductivity and the time to breakdown were determined by not only the conductivity itself but also the temperature dependence of conductivity. Subsequently, we constructed the discharge channel heating model in consideration of the radial and axial temperature distribution. With the given initial temperature distribution, the calculated temporal evolution of current agreed with the measured current waveform just before breakdown. This result revealed that the temperature rise in the center column of discharge channel is the most important factor for the breakdown process. The calculated temporal evolution of the temperature distribution along the center axis revealed that the high temperature region would develop from the tip of the needle electrode toward the center of the gap. In addition, the calculated temporal evolution of the radial temperature distribution suggested that the temperature at the center column of the discharge channel would rise sharply just before breakdown. In conclusion, in the channel heating breakdown in dry air, we clarified the process of the current concentration on the center axis of the discharge channel, as well as the progress of high temperature region or high conductivity region in the axial direction from the tip of the needle electrode.

DOI： 10.1007/978-3-030-31680-8_41

Scopus

環境要因の相互作用を考慮したインバータサージ電圧下における部分放電開始電圧解析

梶武文，浅井洋光，野須敬弘，小島寛樹，早川直樹

電気学会放電・プラズマ・パルスパワー研究会 2019.5.16 電気学会放電・プラズマ・パルスパワー技術委員会

空気中不平等電界下における2次ストリーマ発生条件

浅野竜大，小島寛樹，米須大吾，額賀淳，六戸敏昭，早川直樹

平成31年電気学会全国大会

共通基盤技術としての高電圧絶縁技術の将来展望

小島寛樹，五島久司，大久保仁

平成31年電気学会全国大会

高電圧絶縁技術－9つの核心技術から紐解く歴史と将来展望－

五島久司，小島寛樹，大久保仁

平成31年電気学会全国大会

SF₆ガス中におけるストリーマ/リーダ放電の放射電磁波特性

余増強，小島寛樹，早川直樹

平成31年電気学会全国大会

真空中スパークコンディショニングにおける微小突起の生成および溶融可能性

近藤史規，小島寛樹，福田英昭，榊正幸，早川直樹

平成31年電気学会全国大会

真空インタラプタ開口モデルにおける放電パターン診断の検証

小島寛樹，道念大樹，木村俊則，小倉健太郎，早川直樹

平成31年電気学会全国大会

誘電率傾斜絶縁スペーサにおける流動解析により求めた樹脂分布の妥当性検証

今井隆浩，竹内美和，保科好一，小島寛樹，早川直樹

平成31年電気学会全国大会

FGM絶縁スペーサの誘電率分布逆求解に関する基礎検討

加藤克巳，小島寛樹，早川直樹，満留博，柳瀬博雅，岡本健次，大久保仁

平成31年電気学会全国大会

可変配合注型法によるコーン型FGM絶縁スペーサの作製

落合健太，伊豆淳宏，鳥前勇作，小島寛樹，加藤克巳，渡辺桂司，満留博，柳瀬博雅，岡本健次，早川直樹

平成31年電気学会全国大会

直流ガス絶縁電力機器の極性反転時における傾斜機能材料の電界制御効果

伊豆淳宏，小島寛樹，加藤克巳，早川直樹

平成31年電気学会全国大会

超高圧超電導ケーブルの低誘電損失化に向けたTyvek^®の電気絶縁特性の積層方法依存性

山上浩輝，民部昌孝，小島寛樹，早川直樹

平成31年電気学会全国大会

超電導パンケーキコイルモデルのクエンチ時における液体窒素の動的絶縁破壊特性

民部昌孝，森優次，小島寛樹，礒嶋茂樹，桑田稔，早川直樹

平成31年電気学会全国大会

ツイストペアの部分放電開始電圧における温度および繰り返し周波数依存性

大長勇輝，林亮平，梶武文，小島寛樹，早川直樹

平成31年電気学会全国大会

真空/正帯電固体絶縁物上における交流沿面放電進展特性

大木駿士朗，小島寛樹，浅利直紀，竪山智博，佐々木良輔，早川直樹

平成31年電気学会全国大会

真空中沿面放電経路の初期帯電分布依存性

西田歩成，小島寛樹，飯塚伸介，田中荘，早川直樹

平成31年電気学会全国大会

ガス絶縁開閉装置の絶縁診断高度化に向けた部分放電の電磁波放射メカニズムの解明

小島寛樹

パワーアカデミー研究助成 2019年成果報告会

樹脂充填方法が絶縁スペーサの誘電率傾斜に与える影響－有限体積法に基づく流体解析を用いた樹脂分布の推定－

今井隆浩，保科好一，小島寛樹，早川直樹

電気学会誘電・絶縁材料研究会 2018.12.5 電気学会誘電・絶縁材料技術委員会

Dynamic Breakdown Characteristics of Pancake Coil Model for Resistive Superconducting Fault Current Limiters International conference

N. Hayakawa, M. Mimbu, H. Kojima, S. Isojima, M. Kuwata

2018 Applied Superconductivity Conference

Fabrication of Permittivity Graded Materials (ε-FGM) by Flexible Mixture Casting Method International conference

K. Ochiai, A. Izu, R. Oishi, H. Kojima, H. Mitsudome, H. Yanase, K. Okamoto, K. Kato, N. Hayakawa

2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2018.10.24 IEEE DEIS

Event date： 2018.10

Language：English Presentation type：Poster presentation

Venue：Cancun Country：Mexico

For the downsizing of gas insulated power apparatus, we have proposed the electric field grading technique by 'functionally graded materials' with spatial distribution of permittivity (\varepsilon -FGM). In this paper, we fabricated post-type and truncated cone-type \varepsilon -FGM by a novel and practical technique 'flexible mixture casting method' (FMC method). We confirmed that \varepsilon -FGM by FMC method has the discharge inception voltage improvement effect by both experiment and simulation.

DOI： 10.1109/CEIDP.2018.8544770

Scopus

Combined Effect of Temperature and Humidity of Magnet-Wires on Partial Discharge Inception Voltage under Inverter-Surge Voltage International conference

T. Kaji, H. Asai, H. Kojima, N. Hayakawa

2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2018.10.24 IEEE DEIS

Event date： 2018.10

Language：English Presentation type：Poster presentation

Venue：Cancun Country：Mexico

We investigated the combined effect of temperature and humidity on partial discharge inception voltage (PDIV) of magnet wires under repetitive surge-wave voltages. As the results, the PDIV increased as the temperature increased under uncontrolled humidity, which is peculiar under surge-wave voltage. On the other hand, the PDIV decreased lineally as the temperature increased under controlled humidity. From these results, we found that the PDIV increase under uncontrolled humidity was attributed to the effect of the relative humidity decrease corresponding to the temperature increase. Furthermore, the PDIV was also influenced by the moisture amount in insulation film. Under uncontrolled humidity, the PDIV during the temperature increase was lower than that during the temperature decrease with the hysteresis. We found two reasons for the PDIV hysteresis. One reason is the humidity increase in the air gap due to moisture evaporation from the film. Another reason is the electron emission from the film with the lower first ionization energy. Based on the above reasons, the generation probability of initial electrons during the temperature increase is higher than that during the temperature decrease, which decreases PDIV.

DOI： 10.1109/CEIDP.2018.8544745

Scopus

Estimation of Partial Discharge Inception Voltage under Repetitive Inverter Surge Voltage by Volume-Time Theory International conference

N. Hayakawa, Y. Daicho, T. Kaji, H. Kojima

2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2018.10.24 IEEE DEIS

Event date： 2018.10

Language：English Presentation type：Poster presentation

Venue：Cancun Country：Mexico

We measured the repetition frequency dependence of partial discharge inception voltage (PDIV) of twisted-pair test samples with different specifications under repetitive surge voltages with different waveforms. We also extended the PDIV estimation method with Volume-Time theory under single shot of surge voltage to that under repetitive surge voltage, in consideration of the effect of the repetition frequency on the initial electrons generation probability. The estimated and measured PDIV agreed well under repetitive surge voltage.

DOI： 10.1109/CEIDP.2018.8544814

Scopus

Electric Field Grading by Functionally Graded Materials (FGM) for HVDC Gas Insulated Power Apparatus International coauthorship International conference

N. Hayakawa, R. Oishi, H. Kojima, K. Kato, N. Zebouchi

2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2018.10.23 IEEE DEIS

Event date： 2018.10

Language：English Presentation type：Oral presentation (general)

Venue：Cancun Country：Mexico

Functionally graded materials (FGM) have been investigated as innovative field grading and control techniques for gas insulated power apparatus such as gas insulated switchgears (GIS) and gas insulated transmission lines (GIL). We have so far verified that FGM with the spatial permittivity distribution can control the electric field distribution around GIS spacers under AC and impulse voltage stresses. In this paper, we proposed the new application of FGM for HVDC power apparatus (DC-FGM) and investigated the technical feasibility of the electric field control by DC-FGM. The calculation results revealed that DC-FGM with the spatial conductivity distribution in the spacer bulk can control the electric field distribution around the spacer in consideration of the temperature distribution under DC voltage stress.

DOI： 10.1109/CEIDP.2018.8544834

Scopus

Effect of Initial Electrode Surface and Breakdown Charge on Spark Conditioning in Vacuum under Non-Uniform Electric Field International conference

H. Kojima, M. Noda, H. Fukuda, M. Sakaki, N. Hayakawa

28th International Symposium on Discharges and Electrical Insulation in Vacuum 2018.9.25 Leibniz Institute for Plasma Science and Technology and University of Greifswald – Institute of Physics

Event date： 2018.9

Language：English Presentation type：Poster presentation

Venue：Greifswald Country：Germany

We discuss the effect of initial cathode surface and breakdown (BD) charge on spark conditioning in a rod-plane electrode system, especially with suppressed BD charge. In the case of Cu rod cathode vs. stainless steel plane anode with a large BD charge, the saturated 50% BD field strength at the cathode tip was independent of the initial cathode surface condition, because the large BD charge led to sufficiently large melting of the cathode surface. However, in the case with suppressed BD charge not enough to remove the large weak points, the saturated BD field strength depended on the initial cathode surface condition. On the other hand, in the case of stainless steel rod cathode vs. stainless steel plane anode, the saturated BD field strength was independent of the initial cathode surface condition. In this case, the anode heating would mainly initiate BD. Since the melting of anode was the starting point of BD, the saturated BD field strength would not depend on the initial cathode surface condition regardless of BD charge.

DOI： 10.1109/DEIV.2018.8537140

Scopus

Mechanism behind Increasing Electrostatic Charging Tendency in Aged Mineral-Oil-Immersed Pressboards International conference

H. Morooka, A. Yamagishi, K. Kawamura, H. Kojima, N. Hayakawa

2018 International Conference on Condition Monitoring and Diagnosis 2018.9.25 Curtin University

Event date： 2018.9

Language：English Presentation type：Oral presentation (general)

Venue：Perth Country：Australia

The surface chemical properties of aged pressboards (PBs) were evaluated to investigate the mechanism behind the increasing tendency of electrostatic charges for diagnosing power transformers. The PBs were taken from several aged transformers, and their surface elemental composition and chemical structures were measured by X-ray photoelectron spectroscopy. The PBs properties were measured after being washed by an organic solvent to remove impregnated mineral oil. Carbon (C) and oxygen (O) atoms were mostly observed on virgin PBs surfaces; these are the atoms that compose cellulose polymer, the main component of kraft pulp. In contrast, sulfur (S) and calcium (Ca) atoms were observed on the surfaces of aged PBs in addition to the C and O atoms. Moreover, the surface densities of the Ca atoms had a good correlation with those of the S atoms. While we detected no S atoms inside the aged PBs, we observed almost the same amount of Ca atoms as in the virgin PBs. Mineral oils mainly consist of hydrocarbons, with very small amounts of components such as sulfur compounds derived from crude oil. Heat stress degrades these sulfur compounds. On the other hand, PBs made of kraft pulp contain a very small amount of metal ions, such as Ca ions. We conclude that S atoms observed on aged PB surfaces are a part of the aged sulfur compounds adsorbed from the mineral oil. The adsorption of aged sulfur compounds induced the migration of Ca ions from the inside of the PBs to the surface, which caused the surface density of the Ca ions to increase. This suggests that the accumulation of Ca ions along with the sulfur compounds led to the increasing tendency of electrostatic charges in aged PBs.

DOI： 10.1109/CMD.2018.8535704

Scopus

Thermal-Degradation Mechanism of Mineral-Oil-Immersed Pressboards and Influence of Aging on Pressboard Properties International conference

H. Morooka, A. Yamagishi, K. Kawamura, H. Kojima, N. Hayakawa

2018 International Conference on Condition Monitoring and Diagnosis 2018.9.25 Curtin University

Event date： 2018.9

Language：English Presentation type：Oral presentation (general)

Venue：Perth Country：Australia

The effects of thermal degradation and aging on the properties of mineral-oil-immersed pressboards (PBs) were studied from the viewpoint of diagnosis of power transformers. Specifically, thickness, degree of polymerization (DP), and compressive properties of oil-immersed PBs after heat-accelerated degradation in sealed containers were evaluated. The degree of crystallization (Cr) of oil-immersed PBs was then evaluated by X-ray diffraction (XRD). The evaluation results revealed that after thermal aging, DP decreased. Moreover, thickness, compressive elasticity modulus, and hysteresis loss ratio slightly decreased. Conversely, Cr slightly increased. DP of kraft paper is known to decrease after aging. Simultaneously, several compounds with low molecular weight, such as CO, CO2, and furfurals, are generated, and the tensile strength of kraft paper decreases. It is therefore assumed here that the thickness of PBs decreases very little as they generate low-molecular-weight decomposition compounds and that the decrease in DP causes a slight decrease in the compressive elasticity modulus, E. However, an increase in Cr causes a slight increase in E. As a result, the overall decrease in E is slight.

DOI： 10.1109/CMD.2018.8535770

Scopus

超電導限流器の絶縁設計における液体窒素の動的絶縁破壊特性

民部昌孝，山上浩輝，小島寛樹，礒嶋茂樹，桑田稔，早川直樹

平成30年電気学会電力・エネルギー部門大会

直流ガス絶縁電力機器への傾斜機能材料の適用可能性

伊豆淳宏，大石涼太，小島寛樹，加藤克巳，早川直樹

平成30年電気学会電力・エネルギー部門大会

可変配合注型法による誘電率傾斜機能材料の作製および放電開始電圧向上効果

落合健太，伊豆淳宏，小島寛樹，満留博，柳瀬博雅，岡本健次，加藤克巳，早川直樹

平成30年電気学会電力・エネルギー部門大会

誘電率傾斜絶縁スペーサ作製における樹脂充填挙動の流動解析を用いた可視化

今井隆浩，岡本徹志，保科好一，落合健太，小島寛樹，早川直樹

第49回電気電子絶縁材料システムシンポジウム

加圧空気中の絶縁破壊経路に及ぼす1次ストリーマチャネルの影響

浅野竜大，杉野一樹，小島寛樹，米須大吾，小林金也，六戸敏昭，早川直樹

平成30年電気学会基礎・材料・共通部門大会

Volume-Time理論による繰り返しサージ電圧下の部分放電開始電圧の推定

大長勇輝，梶武文，小島寛樹，早川直樹

平成30年電気学会基礎・材料・共通部門大会

空気中チャネル加熱絶縁破壊発生電圧の閾値の推定

浅野竜大，小島寛樹，米須大吾，小林金也，六戸敏昭，早川直樹

平成30年度電気・電子・情報関係学会東海支部連合大会

真空中交流沿面フラッシオーバ電圧に及ぼす沿面上電界分布の影響

大木駿士朗，小島寛樹，浅利直紀，塩入哲，佐々木良輔，早川直樹

平成30年度電気・電子・情報関係学会東海支部連合大会

乾燥空気中における部分放電形態と放射電磁波強度との相関

余増強，小島寛樹，早川直樹

平成30年度電気・電子・情報関係学会東海支部連合大会

真空中スパークコンディショニング過程における溶融可能な微小突起の大きさの推定

近藤史規，野田昌嗣，小島寛樹，福田英昭，榊正幸，早川直樹

平成30年度電気・電子・情報関係学会東海支部連合大会

高電圧超電導ケーブルにおける低誘電損失合成紙Tyvek^®の電気絶縁特性

山上浩輝，民部昌孝，小島寛樹，早川直樹

平成30年度電気・電子・情報関係学会東海支部連合大会

可変配合注型法による誘電率傾斜機能材料（ε-FGM）の作製における誘電率分布の制御性向上

落合健太，小島寛樹，保科好一，今井隆浩，岡本徹志，早川直樹

平成30年度電気・電子・情報関係学会東海支部連合大会

誘電率傾斜機能材料（ε-FGM）の電界緩和効果の絶縁スペーサ形状依存性

伊豆淳宏，小島寛樹，満留博，柳瀬博雅，岡本健次，加藤克巳，早川直樹

平成30年度電気・電子・情報関係学会東海支部連合大会

液体窒素中におけるGFRPの沿面放電特性

民部昌孝，山上浩輝，小島寛樹，早川直樹

平成30年度電気・電子・情報関係学会東海支部連合大会

真空中陽極加熱絶縁破壊領域におけるコンディショニングと電極初期表面状態の関係

野田昌嗣，大木駿士朗，小島寛樹，福田英昭，榊正幸，早川直樹

平成30年電気学会全国大会

真空中沿面放電進展過程に対する放電経路上の初期帯電分布の影響

生田和也，小島寛樹，飯塚伸介，田中荘，早川直樹

平成30年電気学会全国大会

電界特異性を回避した絶縁スペーサにおける誘電率傾斜機能材料の電界緩和効果

加藤克巳，満留博，柳瀬博雅，岡本健次，小島寛樹，早川直樹

平成30年電気学会全国大会

導電率傾斜機能材料（σ-FGM）による沿面放電電圧向上効果

大石涼太，伊豆淳宏，小島寛樹，加藤克巳，早川直樹

平成30年電気学会全国大会

可変配合注型法によるポスト型誘電率傾斜機能材料の作製

落合健太，大石涼太，小島寛樹，満留博，柳瀬博雅，岡本健次，加藤克巳，早川直樹

平成30年電気学会全国大会

抵抗型超電導限流器を模擬したパンケーキコイルモデルの動的絶縁破壊特性

民部昌孝，山上浩輝，小島寛樹，磯嶋茂樹，桑田稔，早川直樹

平成30年電気学会全国大会

インバータサージ電圧下における巻線の部分放電開始電圧に及ぼす気圧および湿度の複合的影響

梶武文，浅井洋光，小島寛樹，早川直樹

平成30年電気学会全国大会

空気中チャネル加熱絶縁破壊における高導電率チャネルの軸方向進展

杉野一樹，浅野竜大，小島寛樹，米須大吾，小林金也，六戸敏昭，早川直樹

平成30年電気学会全国大会

インバータサージ電圧下における巻線の部分放電開始電圧に及ぼす温度および湿度の複合的影響

梶武文，浅井洋光，小島寛樹，早川直樹

電気学会放電/誘電・絶縁材料/高電圧合同研究会 2018.1.26 電気学会放電/誘電・絶縁材料/高電圧技術委員会

Electric Field Relaxation Effect of Functionally Graded Materials (FGM) with Conductive Multilayer Coating International conference

R. Oishi, H. Kojima, N. Hayakawa, K. Kato

2017 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2017.10.23 IEEE DEIS

Event date： 2017.10

Language：English Presentation type：Oral presentation (general)

Venue：Fort Worth Country：United States

For the insulation design of gas insulated power apparatus, the electric field grading and control are indispensable. We have proposed the application of σ-FGM (Functionally Graded Materials with spatial distribution of conductivity σ) to solid insulators as a novel technique of the electric field grading and control. In this paper, we fabricated the conductive multilayer coating for σ-FGM and investigated the electric field relaxation effect of σ-FGM on a GIS spacer surface. The fabrication results revealed that we could obtain the conductive 3-layer coating by using the dip coating method. The calculation results revealed the technical feasibility of electric field relaxation by σ-FGM with the conductive multilayer coating.

DOI： 10.1109/CEIDP.2017.8257494

Scopus

Surface Flashover Mechanism and Its Application to Diagnosis in Vacuum Interrupter Invited International conference

H. Kojima

4th International Conference on Electric Power Equipment - Switching Technology 2017.10.24 State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University

Event date： 2017.10

Language：English Presentation type：Oral presentation (invited, special)

Venue：Xi'an Country：China

The application of vacuum interrupters and vacuum circuit breakers for higher voltage level is strongly expected. In electrical insulation in vacuum, surface flashover on solid insulator is one of the main problems for the higher voltage vacuum interrupters. In this paper, through the review of our recent researches, we discuss on the initiation and development mechanisms of flashover in the configuration with electric field distribution almost perpendicular to the dielectrics surface. Usually, the flashover was begun by exclusive electron emission at the cathode; however, the large charging on the dielectric surface before the flashover allowed the flashover initiated by secondary electron emission avalanche to occur. The development characteristics of surface flashover agreed with the electron-stimulated outgassing mechanism. The flashover development characteristics were applied to the discharge diagnosis in vacuum, and the effectiveness of our proposed discharge discrimination method was verified.

DOI： 10.1109/ICEPE-ST.2017.8188902

Scopus

空気中チャネル加熱絶縁破壊に至る投入エネルギー密度

杉野一樹，小島寛樹，大嶽敦，小林金也，六戸敏明，早川直樹

平成29年電気学会基礎・材料・共通部門大会

真空中固体絶縁物上の帯電存在時における2次電子なだれ起点の沿面放電メカニズム

生田和也，小島寛樹，飯塚伸介，土屋賢治，早川直樹

平成29年電気学会基礎・材料・共通部門大会

真空中インパルス絶縁破壊における陽極注入エネルギーの推定

野田昌嗣，小島寛樹，長谷川光佑，榊正幸，早川直樹

平成29年電気学会基礎・材料・共通部門大会

Volume Effect of Dynamic Breakdown Strength in LN₂ for Insulation Design of Resistive Superconducting Fault Current Limiters International conference

N. Hayakawa, K. Ishida, M. Mimbu, H. Kojima, S. Isojima, M. Kuwata

13th European Conference on Applied Superconductivity

Fault Current Limitation Coordination in Electric Power Grid with Superconducting Fault Current Limiters International conference

N. Hayakawa, Y. Maeno, H. Kojima

13th European Conference on Applied Superconductivity

抵抗回路モデルによる空気中チャネル加熱絶縁破壊過程

杉野一樹，小島寛樹，大嶽敦，小林金也，六戸敏昭，早川直樹

平成29年度電気・電子・情報関係学会東海支部連合大会

真空中のコンディショニングにおける電極初期表面状態と放電電荷量の相関

野田昌嗣，小島寛樹，福田英昭，榊正幸，早川直樹

平成29年度電気・電子・情報関係学会東海支部連合大会

誘電率/導電率傾斜機能材料（ε/σ-FGM）による放電開始電圧向上の複合効果

大石涼太，小島寛樹，加藤克巳，早川直樹

平成29年度電気・電子・情報関係学会東海支部連合大会

可変配合注型法による誘電率傾斜機能材料（ε-FGM）の作製に向けたコンポジットの選定および混合評価

落合健太，大石涼太，小島寛樹，加藤克巳，早川直樹

平成29年度電気・電子・情報関係学会東海支部連合大会

高電圧超電導ケーブルに向けた低誘電損失材料における部分放電開始電界の圧力依存性

民部昌孝，小島寛樹，早川直樹

平成29年度電気・電子・情報関係学会東海支部連合大会

真空中固体絶縁物上の帯電分布による沿面放電開始メカニズムへの影響

生田和也，小島寛樹，飯塚伸介，田中荘，早川直樹

平成29年度電気・電子・情報関係学会東海支部連合大会

真空中交流部分放電における固体絶縁物上の2次電子放出係数と電荷挙動

加藤丞，小島寛樹，早川直樹

平成29年度電気・電子・情報関係学会東海支部連合大会

電力系統の過渡安定度を考慮した超電導限流器の限流協調

早川直樹，前野有哉，小島寛樹

平成29年電気学会電力・エネルギー部門大会

変圧器向け油含浸プレスボードの熱劣化後の圧縮特性評価

師岡寿至，宮原秀幸，山岸明，三瓶宏幸，早川直樹，小島寛樹

平成29年電気学会電力・エネルギー部門大会

真空インタラプタ内放電パターン診断における放電前シールド電位の影響

小島寛樹，道念大樹，木村俊則，小倉健太郎，早川直樹

平成29年電気学会電力・エネルギー部門大会

真空中放電電荷量を制御したコンディショニング過程における電極表面損傷の修復可能性

野田昌嗣，小島寛樹，長谷川光佑，榊正幸，早川直樹

平成29年電気学会電力・エネルギー部門大会

導電率傾斜機能材料（σ-FGM）を適用したGISスペーサの放電開始電圧の理論的推定

大石涼太，小島寛樹，加藤克巳，早川直樹

平成29年電気学会電力・エネルギー部門大会

A Novel Fabrication Technique of Permittivity Graded Materials by Flexible Mixture Casting Method for GIS Spacers International conference

N. Hayakawa, Y. Miyaji, K. Ochiai, H. Kojima, K. Kato

20th International Symposium on High Voltage Engineering

Criteria for Channel Heating Breakdown under Non-Uniform Electric Field in Air International conference

H. Kojima, K. Sugino, A. Ohtake, K. Kobayashi, T. Kato, T. Rokunohe

20th International Symposium on High Voltage Engineering

Controlling Breakdown Charge for Conditioning Procedure in Vacuum under Non-uniform Electric Field International conference

H. Kojima, M. Noda, K. Hasegawa, M. Sakaki, N. Hayakawa

20th International Symposium on High Voltage Engineering

超電導限流器の開発動向と技術課題

早川直樹，小島寛樹

電気学会金属・セラミックス/超電導機器合同研究会 2017.7.21 電気学会金属・セラミックス/超電導機器技術委員会

放電チャネル進展時の電流-電磁波相関に基づく電磁波放射源に関する検討

加藤拓，杉野一樹，小島寛樹，早川直樹

平成29年電気学会全国大会

真空中交流沿面フラッシオーバに及ぼす帯電極性・分布の影響

川口王嗣，加藤丞，小島寛樹，浅利直紀，塩入哲，早川直樹

平成29年電気学会全国大会

真空中固体絶縁物上の初期帯電電位分布が沿面放電メカニズムに及ぼす影響

生田和也，小島寛樹，飯塚伸介，土屋賢治，早川直樹

平成29年電気学会全国大会

空気中チャネル加熱絶縁破壊に至るエネルギーに関する考察

杉野一樹，小島寛樹，大嶽敦，小林金也，加藤達朗，六戸敏昭，早川直樹

平成29年電気学会全国大会

超電導限流器を含む電力システムの限流協調

前野有哉，小島寛樹，早川直樹

平成29年電気学会全国大会

超電導限流器の絶縁設計における液体窒素の動的絶縁破壊電界の体積効果

石田一樹，民部昌孝，小島寛樹，礒嶋茂樹，桑田稔，早川直樹

平成29年電気学会全国大会

可変配合注型法による誘電率傾斜機能材料を適用したGISスペーサの絶縁破壊電圧の推定

宮路仁崇，大石涼太，落合健太，小島寛樹，加藤克巳，早川直樹

平成29年電気学会全国大会

導電性多層コーティングによる導電率傾斜機能材料（σ-FGM）の作製・評価

大石涼太，宮路仁崇，小島寛樹，加藤克巳，早川直樹

平成29年電気学会全国大会

真空中コンディショニング過程における放電電荷量制御の効果

野田昌嗣，小島寛樹，長谷川光佑，榊正幸，早川直樹

平成29年電気学会全国大会

誘電率傾斜機能材料（ε-FGM）を用いたGISスペーサモデルの作製とSF₆ガス中絶縁破壊電圧の理論的推定

宮路仁崇，小島寛樹，加藤克巳，早川直樹

電気学会放電/誘電・絶縁材料/高電圧合同研究会

Fabrication and Evaluation of Permittivity Graded Materials with SrTiO₃ Particles and Localized Conductive Layer International conference

Y. Miyaji, H. Kojima, K. Kato, N. Hayakawa

2016 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2016.10.18 IEEE Dielectrics and Electrical Insulation Society

Event date： 2016.10

Language：English Presentation type：Poster presentation

Venue：Toronto Country：Canada

For the relaxation of electric field distribution around the solid insulator in power apparatus, the application of functionally graded materials (FGM) with spatial distribution of permittivity (ϵ) and conductivity (σ) is proposed. In this paper, ϵ-FGM with SrTiO3/SiO2 particles and localized conductive layers for σ-FGM are fabricated and evaluated. The fabrication results suggested that the coaxial disk-type ϵ-FGM with SrTiO3/SiO2 particles can reduce the electric field better than ϵ-FGM with TiO2/SiO2 particles. The fundamental fabrication techniques of the solid insulator with the localized conductive layers are also discussed toward σ-FGM.

DOI： 10.1109/CEIDP.2016.7785622

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000391639700129

Electric Field Reduction by Functionally Graded Materials (FGM) with Permittivity and Conductivity Distribution International conference

N. Hayakawa, Y. Miyaji, H. Kojima, K. Kato

2016 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2016.10.18 IEEE Dielectrics and Electrical Insulation Society

Event date： 2016.10

Language：English Presentation type：Poster presentation

Venue：Toronto Country：Canada

Functionally graded materials (FGM) have been developed for the electric field control around the solid insulator in power apparatus. In particular, FGM with spatial distribution of permittivity (ϵ-FGM) and/or conductivity (σ-FGM) are expected to contribute to the electric field reduction leading to the size reduction of gas insulated switchgears (GIS), etc. In this paper, the electric field reduction effect of ϵ-FGM, σ-FGM and their combined ϵ/σ-FGM for a GIS spacer is investigated. Simulation results revealed the technical feasibility of electric field reduction by combined ϵ/σ-FGM for different frequencies.

DOI： 10.1109/CEIDP.2016.7785621

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000391639700128

Discharge Pattern Discrimination for Composite Insulation System in Vacuum Interrupter International conference

F. Kong, H. Kojima, T. Kimura, M. Tsukima, N. Hayakawa

27th International Symposium on Discharges and Electrical Insulation in Vacuum 2016.9.22 Xi’an Jiaotong University

Optimum Breakdown Charge for Spark Conditioning in Vacuum under Non-uniform Electric Field International conference

H. Kojima, T. Takahashi, M. Noda, K. Hasegawa, M. Sakaki, N. Hayakawa

27th International Symposium on Discharges and Electrical Insulation in Vacuum 2016.9.19 Xi’an Jiaotong University

Event date： 2016.9

Language：English Presentation type：Oral presentation (general)

Venue：Suzhou Country：China

Spark conditioning is one of the effective measures to improve the dielectric strength in vacuum. In this paper, we obtained the breakdown (BD) charge dependence for spark conditioning in vacuum under various non-uniform electric field and anode materials, and discussed the BD mechanism in terms of BD based on anode heating or cathode heating. Experimental results revealed that, in the case of BD based on anode heating, the longer the gap distance was, the larger the BD charge to obtain maximum dielectric strength was. On the other hand, in the case of BD based on cathode heating, the BD charge for maximum dielectric strength was smaller than that in the case of BD based on anode heating. From these results, we can estimate the optimal BD charge for the spark conditioning in vacuum.

DOI： 10.1109/DEIV.2016.7748662

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000402729100002

UHF法における部分放電電流波形と電磁波強度との相関

加藤拓，小島寛樹，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

液体窒素の動的絶縁破壊特性におけるギャップ長依存性

石田一樹，小島寛樹，礒嶋茂樹，桑田稔，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

可変配合注型法による傾斜機能材料（FGM）の誘電率分布と電界緩和効果

宮路仁崇，小島寛樹，加藤克巳，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

雷インパルス印加時における導電率傾斜機能材料（σ-FGM）の電界緩和効果

大石涼太，宮路仁崇，小島寛樹，加藤克巳，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

CO₂ガス中におけるチャネル加熱絶縁破壊メカニズム

杉野一樹，小島寛樹，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

超電導限流器が導入された電力システムにおける過渡安定度を考慮した限流協調

前野有哉，小島寛樹，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

真空中コンディショニングおける陽極損耗と放電電荷量の相関

野田昌嗣，小島寛樹，長谷川光佑，榊正幸，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

真空中交流電圧下の帯電形成による部分放電開始電圧とフラッシオーバ電圧の相関

川口王嗣，小島寛樹，浅利直紀，塩入哲，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

直流極性反転時における真空中固体絶縁物上の電荷挙動

生田和也，小島寛樹，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会

高電圧超電導ケーブルの低誘電損失化に向けたポーラス紙の電気絶縁特性

石田一樹，小島寛樹，早川直樹

平成28年電気学会電力・エネルギー部門大会

真空インタラプタにおけるシールド電位の非接触測定を用いた放電パターン推定

小島寛樹，孔飛，木村俊則，月間満，早川直樹

平成28年電気学会電力・エネルギー部門大会

SrTiO₃/SiO₂を用いた同軸ディスク型誘電率傾斜機能材料の作製およびGISスペーサの電界緩和効果

宮路仁崇，大石涼太，小島寛樹，加藤克巳，早川直樹

平成28年電気学会電力・エネルギー部門大会

放射電磁波によるノイズ環境下のGIS内部部分放電識別

早川直樹，汲田将之，小島寛樹，吉田昌展

平成28年電気学会電力・エネルギー部門大会

導電性多層コーティングによる導電率傾斜機能材料（σ-FGM）の電界緩和効果

大石涼太，宮路仁崇，小島寛樹，加藤克巳，早川直樹

平成28年電気学会基礎・材料・共通部門大会

空気中1次ストリーマ残留空間の電界が2次ストリーマ進展に及ぼす影響

杉野一樹，小島寛樹，大嶽敦，小林金也，加藤達朗，六戸敏昭，早川直樹

平成28年電気学会基礎・材料・共通部門大会

SrTiO₃を用いた可変配合注型法による誘電率傾斜機能材料（ε-FGM）の電界緩和効果

宮路仁崇，大石涼太，小島寛樹，加藤克巳，早川直樹

平成28年電気学会基礎・材料・共通部門大会

Breakdown Characteristics and Mechanisms of Liquid Nitrogen under Transient Thermal Stress for Superconducting Fault Current Limiters International conference

N. Hayakawa, T. Matsuoka, H. Kojima, S. Isojima, M. Kuwata

2016 Applied Superconductivity Conference

Electrical Insulation Characteristics and Mechanisms of Low Dielectric Loss Materials for High-Voltage HTS Cables International conference

N. Hayakawa, K. Ishida, T. Matsuoka, H. Kojima

2016 Applied Superconductivity Conference

絶縁性液体適用機器の放電現象、劣化現象、診断技術

森繁和，小迫雅裕，小島寛樹，福地哲生，栗原二三夫，小林広和，宮島極

平成28年電気学会全国大会

真空中における陰極めっきによる絶縁性能向上

高橋達也，小島寛樹，長谷川光佑，榊正幸，早川直樹

平成28年電気学会全国大会

真空中スパークコンディショニングにおける最低破壊電圧の向上手法

高橋達也，野田正嗣，小島寛樹，長谷川光佑，榊正幸，早川直樹

平成28年電気学会全国大会

真空インタラプタ内の放電パターンの識別手法に関する考察

孔飛，小島寛樹，木村俊則，月間満，早川直樹

平成28年電気学会全国大会

TiO₂/PTFEを用いた誘電率傾斜機能材料（FGM）による電力機器の電界緩和効果

張逸凡，宮路仁崇，栗本宗明，小島寛樹，加藤克巳，早川直樹

平成28年電気学会全国大会

液体窒素の動的絶縁破壊特性を考慮した超電導限流器の絶縁設計に関する考察

松岡達矢，石田一樹，小島寛樹，礒嶋茂樹，桑田稔，早川直樹

平成28年電気学会全国大会

高電圧超電導ケーブルに向けた低誘電損失材料の部分放電開始特性

石田一樹，松岡達矢，小島寛樹，早川直樹

平成28年電気学会全国大会

可変配合注型法を用いた誘電率傾斜機能材料（FGM）によるGISスペーサの電界緩和効果

宮路仁崇，栗本宗明，小島寛樹，加藤克巳，早川直樹

平成28年電気学会全国大会

初期帯電を考慮した真空中沿面放電開始メカニズム

伊吹憲哉，生田和也，小島寛樹，飯塚伸介，土屋賢治，早川直樹

平成28年電気学会全国大会

SrTiO₃を用いた誘電率傾斜機能材料および局部導電性コーティングの作製・評価

宮路仁崇，栗本宗明，小島寛樹，加藤克巳，早川直樹

電気学会放電/誘電・絶縁材料/高電圧合同研究会

ナノ粒子添加絶縁油の電気絶縁特性

近藤貴文，小島寛樹，花井正広，早川直樹

電気学会静止器研究会 2015.12.11 電気学会静止器技術委員会

真空中におけるスパークコンディショニングの最適放電電荷量

高橋達也，小島寛樹，長谷川光佑，榊正幸，早川直樹

電気学会放電/開閉保護/高電圧合同研究会 2015.11.4 電気学会放電/開閉保護/高電圧技術委員会

Fluctuation and Change of Partial Discharge Inception Voltage under High Humidity for Rectangular Wire Motors International conference

T. Wakimoto, H. Kojima, N. Hayakawa

2015 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2015.10.19 IEEE Dielectrics and Electrical Insulation Society

Event date： 2015.10

Language：English Presentation type：Oral presentation (general)

Venue：Ann Arbor Country：United States

This paper aims to clarify the mechanism of fluctuation and change characteristics in the partial discharge inception voltage (PDIV) between motor coils constructed from rectangular wires under high humidity environments. To achieve this, the PDIV at 50Hz after pre-discharge between the coil wires were measured at 90% RH for a motor stator and test pieces, both of which were composed of rectangular wires. Electric field analyses were performed for several contact patterns between the rectangular wires for different values of surface conductivity. As the results, we clarified that the PDIV fluctuation and change in rectangular wire motors under high humidity can be caused by a superposition of the various PDIV characteristics for each contact pattern between the coil wires in the motor.

DOI： 10.1109/CEIDP.2015.7351997

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000370070700014

真空中の複合電極系における放電進展特性

孔飛，中野裕介，小島寛樹，木村俊則，月間満，早川直樹

平成27年度電気・電子・情報関係学会東海支部連合大会

液体窒素の動的絶縁破壊特性における電極直径および圧力依存性

松岡達矢，石田一樹，小島寛樹，礒嶋茂樹，桑田稔，早川直樹

平成27年度電気・電子・情報関係学会東海支部連合大会

直流/インパルス重畳電圧下における真空中沿面放電特性

伊吹憲哉，中野裕介，小島寛樹，飯塚伸介，土屋賢治，早川直樹

平成27年度電気・電子・情報関係学会東海支部連合大会

真空中不平等電界下におけるコンディショニング飽和後の絶縁破壊機構のギャップ長依存性

高橋達也，小島寛樹，長谷川光佑，榊正幸，早川直樹

平成27年度電気・電子・情報関係学会東海支部連合大会

SiO₂ナノ粒子添加アルキルベンゼンの交流絶縁破壊電圧におけるナノ粒子濃度依存性

近藤貴文，小島寛樹，花井正広，早川直樹

平成27年度電気・電子・情報関係学会東海支部連合大会

誘電率/導電率傾斜機能材料（ε/σ-FGM）による電界制御の複合効果

宮路仁崇，栗本宗明，小島寛樹，加藤克巳，早川直樹

平成27年度電気・電子・情報関係学会東海支部連合大会

局部導電性コーティングによるGISスペーサの電界緩和効果

宮路仁崇，小島寛樹，加藤克巳，早川直樹

平成27年電気学会基礎・材料・共通部門大会

ナノ粒子添加絶縁油の交流絶縁破壊電圧の油中水分量依存性

近藤貴文，小島寛樹，花井正広，早川直樹

平成27年電気学会基礎・材料・共通部門大会

真空中不平等電界下におけるスパークコンディショニング特性の陽極材料およびギャップ長依存性

高橋達也，小島寛樹，長谷川光佑，斉藤仁，榊正幸，早川直樹

平成27年電気学会基礎・材料・共通部門大会

真空中の浮遊電極を介する沿面放電特性

孔飛，中野裕介，小島寛樹，木村俊則，月間満，早川直樹

平成27年電気学会基礎・材料・共通部門大会

Pressure Dependence and Size Effect of Dynamic Breakdown Characteristics of LN₂ under Transient Electrical/Thermal Combined Stress International conference

N. Hayakawa, T. Matsuoka, K. Ishida, H. Kojima, S. Isojima, M. Kuwata

12th European Conference on Applied Superconductivity

誘電率/導電率複合傾斜機能材料（ε/σ-FGM）によるGISスペーサの電界緩和効果

宮路仁崇，石黒純也，栗本宗明，小島寛樹，加藤克巳，早川直樹

平成27年電気学会電力・エネルギー部門大会

高電圧超電導ケーブルに向けた低誘電損失材料の電気絶縁特性

石田一樹，松岡達矢，小島寛樹，早川直樹

平成27年電気学会電力・エネルギー部門大会

Kerr Electro-optic Field Measurement and Electrical Insulation Techniques in HVDC Oil-Pressboard Composite Insulation Systems International conference

H. Okubo, H. Kojima, N. Hayakawa, S. Jaufer, C. Krause

19th International Symposium on High Voltage Engineering

Breakdown Mechanism Based on Secondary Streamer Propagation and Channel Heating under Non-uniform Electric Field in Air International conference

H. Kojima, T. Kitamura, S. Goto, K. Kobayashi, T. Kato, T. Rokunohe, N. Hayakawa

19th International Symposium on High Voltage Engineering

Reduction of Measurement Fluctuation of Partial Discharge Inception Voltage for Inverter-fed Rectangular Wire Motors International conference

T. Wakimoto, H. Kojima, N. Hayakawa

19th International Symposium on High Voltage Engineering

Asset Management for Power Apparatus with Intelligent Grid Management System (IGMS) International conference

H. Kojima, K. Fukaya, N. Hayakawa, M. Hanai, H. Okubo

19th International Symposium on High Voltage Engineering

Breakdown and Flashover Characteristics for Discharge via Floating Electrode and Solid Insulator in Vacuum International conference

F. Kong, Y. Nakano, H. Kojima, T. Kimura, M. Tsukima, N. Hayakawa

19th International Symposium on High Voltage Engineering

Impulse Surface Flashover Development with Transient Charging on Solid Insulators in Vacuum through Streak Image Observation International conference

Y. Nakano, H. Kojima, K. Tsuchiya, N. Hayakawa

19th International Symposium on High Voltage Engineering

Breakdown Charge Dependence for Saturation of Spark Conditioning under Non-uniform Electric Field in Vacuum International conference

T. Takahashi, H. Kojima, K. Hasegawa, H. Saito, M. Sakaki, N. Hayakawa

19th International Symposium on High Voltage Engineering

電力系統最適運用システム（IGMS）を用いた電力機器のアセットマネジメント

深谷皇紀，小島寛樹，花井正広，早川直樹

平成27年電気学会全国大会

スパイラルアンテナによるGIS外部漏出電磁波測定

汲田将之，小島寛樹，吉田昌展，早川直樹

平成27年電気学会全国大会

真空中不平等電界下におけるスパークコンディショニング効果の陽極材料依存性

高橋達也，小島寛樹，長谷川光佑，斉藤仁，榊正幸，早川直樹

平成27年電気学会全国大会

SrTiO₃/BNを用いた誘電率傾斜機能材料によるGISスペーサの電界緩和効果

張逸凡，石黒純也，栗本宗明，小島寛樹，加藤克巳，早川直樹

平成27年電気学会全国大会

液体窒素の動的絶縁破壊特性における圧力依存性

松岡達矢，石田一樹，小島寛樹，礒嶋茂樹，桑田稔，早川直樹

平成27年電気学会全国大会

超純水における絶縁破壊電界の温度・流量および圧力依存性

佐藤広治，近藤貴文，小島寛樹，花井正広，早川直樹

平成27年電気学会全国大会

ナノ粒子添加絶縁油の交流絶縁破壊特性におけるギャップ長依存性

近藤貴文，佐藤広治，小島寛樹，花井正広，早川直樹

平成27年電気学会全国大会

N₂/O₂混合ガス中における1次ストリーマ進展特性

北村卓也，後藤成彦，小島寛樹，小林金也，加藤達朗，六戸敏昭，早川直樹

平成27年電気学会全国大会

CO₂/N₂混合ガス中1次ストリーマ進展過程

後藤成彦，北村卓也，小島寛樹，早川直樹

平成27年電気学会全国大会

真空中交流部分放電における帯電形成へのアルミナ絶縁物欠陥の影響

仲田祐希，小島寛樹，早川直樹，浅利直紀，塩入哲，松尾和宏

平成27年電気学会全国大会

真空中沿面フラッシオーバ進展過程における過渡帯電分布と2次電子なだれの時間推移

中野裕介，小島寛樹，土屋賢治，早川直樹

平成27年電気学会全国大会

真空中沿面フラッシオーバ進展過程における導電チャネル形成時間

孔飛，中野裕介，小島寛樹，木村俊則，月間満，早川直樹

平成27年電気学会全国大会

平角線モータにおける部分放電開始電圧のばらつき低減方法

脇本亨，小島寛樹，早川直樹

電気学会誘電・絶縁材料/電線・ケ－ブル合同研究会 2015.3.13 電気学会誘電・絶縁材料/電線・ケ－ブル技術委員会

真空中沿面フラッシオーバ進展過程における絶縁物上過渡帯電存在時の実効的2次電子放出係数

中野裕介，小島寛樹，土屋賢治，早川直樹

電気学会放電/誘電・絶縁材料/高電圧合同研究会 2015.1.30 電気学会放電/誘電・絶縁材料/高電圧技術委員会

真空中不平等電界下におけるスパークコンディショニングの放電電荷量依存性

高橋達也，小島寛樹，長谷川光佑，斉藤仁，榊正幸，早川直樹

電気学会放電/誘電・絶縁材料/高電圧合同研究会 2015.1.30 電気学会放電/誘電・絶縁材料/高電圧技術委員会

Influence of Space Charge by Primary and Secondary Streamers on Breakdown Mechanism under Non-uniform Electric Field in Air International conference

T. Kitamura, H. Kojima, K. Kobayashi, T. Kato, T. Rokunohe, N. Hayakawa

2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2014.10.20 IEEE Dielectrics and Electrical Insulation Society

Event date： 2014.10

Language：English Presentation type：Poster presentation

Venue：Des Moines Country：United States

We have clarified that the primary and secondary streamers have a significant impact on breakdown mechanism in air. In this paper, we focused on the highly-conductive channel progress breakdown, and considered the initiation condition of highly-conductive channel from the viewpoint of the secondary streamer initiation. We revealed that the highly-conductive channel initiation voltage in the case with the grounded electrode covered by a dielectric barrier was higher than that without the barrier. We suggested that the electric field relaxation effect of the residual positive space charges formed by the primary streamer is greater than that by the secondary streamer. The highly-conductive channel is initiated from the region where the electric field relaxation is weak.

DOI： 10.1109/CEIDP.2014.6995797

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000352763100026

Electric Field Control in Coaxial Disk-Type Solid Insulator by Functionally Graded Materials (FGM) International conference

J. Ishiguro, M. Kurimoto, H. Kojima, K. Kato, H. Okubo, N. Hayakawa

2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2014.10.22 IEEE Dielectrics and Electrical Insulation Society

Event date： 2014.10

Language：English Presentation type：Oral presentation (general)

Venue：Des Moines Country：United States

We have been investigating functionally graded materials (FGM) with the purpose of controlling and relaxing electric field in solid insulator of electric power apparatus. FGM is characterized by the spatial distribution of dielectric permittivity in a solid insulator, and can control the surrounding electric field distribution in power apparatus such as gas insulated switchgears (GIS) and epoxy mold transformers. In this paper, we fabricated a coaxial disk-type GLP (grading to lower permittivity)-FGM for the GIS spacer. Experimental results revealed that we could fabricate GLP-FGM with relative permittivity distribution from 8.2 to 5.3 in the coaxial disk-type spacer. According to the numerical analysis, the maximum electric field at the HV-electrode/spacer interface was reduced by 12 % for the coaxial disk-type GLP-FGM than that of the conventional spacer with uniform permittivity.

DOI： 10.1109/CEIDP.2014.6995799

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000352763100129

Conditioning Development in Vacuum Based on Breakdown Probability Distribution International conference

H. Kojima, Y. Otake, M. Sakaki, H. Saito, K. Hasegawa, N. Hayakawa

2014 International Symposium on Discharges and Electrical Insulation in Vacuum 2014.9.29 Bhabha Atomic Research Center and Indian Vacuum Society

Event date： 2014.9 - 2014.10

Language：English Presentation type：Oral presentation (general)

Venue：Mumbai Country：India

Spark conditioning is important for the enhancement of insulation strength in vacuum. In order to enhance the insulation performance of vacuum circuit breakers, we have to clarify the conditioning effect and improve a conditioning procedure. In this paper, we discuss the conditioning process of Cu and stainless steel rod electrodes based on breakdown (BD) probability distribution. We applied a negative impulse voltage to a rod-plane electrode configuration. We adopted two procedures for the voltage application, i.e. up-down and 3 times methods. For the Cu rod with the up-down method, BD voltage increased by the conditioning effect, however, the minimum BD voltage did not increase or even decreased due to the damage by BD. A moderate conditioning procedure, e.g. 3 times method, could increase the minimum BD voltage as well as the stabilization of insulation strength. The Weibull analysis of the development of a BD probability distribution has enabled us to evaluate the damaging effect. Based on these results, we can discuss a suitable conditioning procedure.

DOI： 10.1109/DEIV.2014.6961607

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000369858100005

Influence of Heat Treatment in Atmosphere for Surface Flashover Characteristics on Alumina in Vacuum International conference

N. Asari, T. Shioiri, J. Sato, K. Matsuo, H. Kojima, N. Hayakawa

2014 International Symposium on Discharges and Electrical Insulation in Vacuum 2014.9.30 Bhabha Atomic Research Center and Indian Vacuum Society

Event date： 2014.9 - 2014.10

Language：English Presentation type：Poster presentation

Venue：Mumbai Country：India

Alumina Ceramics are widely used for vacuum insulation in devices such as vacuum interrupters. In development and design of vacuum interrupters, it is very important to improve the flashover characteristics on alumina ceramic surfaces in a vacuum. Thus, it is necessary to clarify the flashover mechanism on alumina ceramics in a vacuum. From past research, it is well-known that these characteristics are influenced by the insulation material, its surface condition, surface charging of the insulator and so on.(1) This paper presents the results of measurements of surface flashover characteristics and the cathode luminescence (C.L.) spectra after heat treatment in the atmosphere. These results are compared with those without heat treatment in the atmosphere. It is thus found that oxygen defects on an alumina ceramic surface decreases and the flashover voltage is improved by heat treatment in the atmosphere.

DOI： 10.1109/DEIV.2014.6961626

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000369858100024

Transient Charging for Impulse Surface Flashover Development in Vacuum International conference

Y. Nakano, H. Kojima, K. Tsuchiya, N. Hayakawa

2014 International Symposium on Discharges and Electrical Insulation in Vacuum 2014.9.29 Bhabha Atomic Research Center and Indian Vacuum Society

Event date： 2014.9 - 2014.10

Language：English Presentation type：Oral presentation (general)

Venue：Mumbai Country：India

Surface discharge on solid insulator in vacuum is one of the significant issues in the development of vacuum circuit breakers and vacuum interrupters. By measuring induced current in electrostatic probes behind alumina dielectrics due to explosive electron emission (EEE) at surface flashover inception, we studied transiently formed charge characteristics on the alumina dielectrics in the development process of surface flashover. From experimental results, we found that EEE affects the flashover development through two effects of the transient charge: one is the suppression of the EEE current by the relaxation of the electric field below the cathode, the other is promotion of the secondary electron emission avalanche. In the latter effects, because of negative charge on the alumina dielectrics below the cathode, the secondary electron can fly longer along the alumina surface. As a result, the current channel on the alumina dielectrics is formed more easily.

DOI： 10.1109/DEIV.2014.6961618

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000369858100016

Planning Maintenance Strategy for Power Apparatus and T&D System with Intelligent Grid Management System (IGMS) International conference

H. Kojima, K. Fukaya, M. Hanai, N. Hayakawa, H. Okubo

International Conference on Condition Monitoring and Diagnosis 2014

誘電率傾斜機能材料（FGM）によるGISスペーサの電界制御・緩和効果

石黒純也，栗本宗明，小島寛樹，加藤克巳，早川直樹

平成26年電気学会電力・エネルギー部門大会

電力系統最適運用システム（IGMS）による電力機器の保守戦略とコスト削減効果

深谷皇紀，小島寛樹，花井正広，大久保仁，早川直樹

平成26年電気学会電力・エネルギー部門大会

スパイラルアンテナを用いたGIS内電磁波放射・伝搬特性の金属異物長依存性

汲田将之，小島寛樹，吉田昌展，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

真空中平等電界下におけるスパークコンディショニングの放電電荷量および電極材料依存性

高橋達也，小島寛樹，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

空気中1次ストリーマ進展と放電電流の相関

北村卓也，後藤成彦，小島寛樹，小林金也，加藤達朗，六戸敏昭，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

真空中の絶縁破壊時における浮遊電極電位の過渡的推移

孔飛，中野裕介，小島寛樹，木村俊則，月間満，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

油浸複合短ギャップ絶縁構成の直流電界下における電荷欠乏現象

吉川太郎，小島寛樹，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

IGMS（Intelligent Grid Management System）による変圧器の劣化制御を考慮した保守戦略

深谷皇紀，小島寛樹，花井正広，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

超電導電力機器のクエンチ環境下における液体窒素中の気泡挙動と動的絶縁破壊電界

松岡達矢，小島寛樹，礒嶋茂樹，野口浩二，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

傾斜機能材料（FGM）のフィラー粒径分布による誘電率分布制御

石黒純也，栗本宗明，小島寛樹，加藤克巳，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

真空中沿面フラッシオーバ進展の制御および抑制

中野裕介，小島寛樹，土屋賢治，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

真空中交流部分放電による帯電が沿面フラッシオーバ特性に及ぼす影響

仲田祐希，小島寛樹，浅利直紀，塩入哲，松尾和宏，早川直樹

平成26年度電気・電子・情報関係学会東海支部連合大会

空気中における2次ストリーマ進展およびチャネル加熱による絶縁破壊機構

北村卓也，後藤成彦，小島寛樹，小林金也，六戸敏昭，早川直樹

平成26年電気学会基礎・材料・共通部門大会

真空中不平等電界下におけるCu-Cr電極のインパルスコンディショニングの飽和条件

高橋達也，大竹泰智，小島寛樹，長谷川光佑，斉藤仁，榊正幸，早川直樹

平成26年電気学会基礎・材料・共通部門大会

真空中沿面フラッシオーバ進展時の過渡帯電による放出電子電流抑制効果

中野裕介，小島寛樹，土屋賢治，早川直樹

平成26年電気学会基礎・材料・共通部門大会

スパイラルアンテナによるSF₆ガス中部分放電放射電磁波測定

汲田将之，小島寛樹，吉田昌展，早川直樹

平成26年電気学会基礎・材料・共通部門大会

Quench-induced Dynamic Breakdown Characteristics of LN₂ and LN₂/PPLP Composite Electrical Insulation System for Superconducting Power Apparatus International conference

N. Hayakawa, T. Matsuoka, S. Nishimachi, H. Kojima, M. Hanai

Applied Superconductivity Conference

Fault Current Limiting Cooperation in Power Transmission System with Superconducting Fault Current Limiting Cables (SFCLC) International conference

H. Kojima, T. Osawa, M. Hanai, N. Hayakawa

Applied Superconductivity Conference

Breakdown Characteristics and Size Effect in Sub-Cooled Liquid Nitrogen International conference

N. Hayakawa, S. Nishimachi, T. Matsuoka, H. Kojima, M. Hanai, H. Okubo

18th International Conference on Dielectric Liquids 2014.7.3 IEEE Dielectrics and Electrical Insulation Society

Event date： 2014.6 - 2014.7

Language：English Presentation type：Oral presentation (general)

Venue：Bled Country：Slovenia

We systematically investigated and discussed the ac breakdown (BD) characteristics and mechanisms of liquid nitrogen (LN2) for different pressures (0.1-0.3 MPa) and temperatures (65-77 K) under quasi-uniform electric field (field utilization factor ζ = 0.986-0.674). The BD strength (EB) in sub-cooled LN2 (SLN2) was analyzed and discussed in terms of size effect, taking account of the stressed liquid volume (SLV) with the electric field distribution in SLN2. We also included the other reseachers' data on BD characteristics of LN2, and extended the evaluation by applying the concept of α % SLV (SLV with the electric field strength higher than the decisive electric field factor (α) of the highest electric field strength). As the result, we found that EB with the 50 % probability decreased linearly with the increase in α % SLV on a universal line, i.e. EB = 78.4 × (α % SLV) -1/8.15, irrespective of the pressure and temperature of LN2.

DOI： 10.1109/ICDL.2014.6893087

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000360485100018

空気中の絶縁破壊チャネル発生に及ぼす部分放電残留電荷の影響

北村卓也，小島寛樹，小林金也，加藤達朗，六戸敏昭，早川直樹

平成26年電気学会全国大会

ガス中部分放電特性と放射電磁波特性との相関性

汲田将之，水野龍之介，小島寛樹，花井正広，吉田昌展，早川直樹

平成26年電気学会全国大会

電力系統最適運用システム（IGMS）による系統全体の電力機器に対する最適保守戦略の立案

深谷皇紀，小島寛樹，花井正広，大久保仁，早川直樹

平成26年電気学会全国大会

超電導限流ケーブル（SFCLC）が導入された電力システムにおける故障電流の限流協調

大澤岳士，小島寛樹，花井正広，早川直樹

平成26年電気学会全国大会

超電導ケーブルにおける液体窒素/絶縁紙複合絶縁系の動的電気絶縁特性

西町誠一郎，小島寛樹，花井正広，早川直樹

平成26年電気学会全国大会

超電導電力機器における液体窒素の動的絶縁破壊特性

松岡達矢，西町誠一郎，小島寛樹，礒嶋茂樹，野口浩二，早川直樹

平成26年電気学会全国大会

傾斜機能材料（FGM）を適用したGISスペーサの電界緩和効果の検証

石黒純也，栗本宗明，小島寛樹，花井正広，加藤克巳，早川直樹

平成26年電気学会全国大会

エナメル平角電線の部分放電開始電圧および表面電位分布推移に与えるプレ放電の影響

脇本亨，小島寛樹，花井正広，早川直樹

平成26年電気学会全国大会

超純水の短ギャップ交流絶縁破壊特性

佐藤広治，小島寛樹，花井正広，加藤克巳，早川直樹

平成26年電気学会全国大会

液体窒素/ポーラス絶縁紙複合絶縁系の電気絶縁特性

西町誠一郎，松岡達矢，栗本宗明，小島寛樹，花井正広，早川直樹

平成26年電気学会全国大会

真空中不平等電界下におけるコンディショニング進展の昇圧方法依存性

大竹泰智，高橋達也，小島寛樹，長谷川光佑，斉藤仁，榊正幸，早川直樹

平成26年電気学会全国大会

真空中交流部分放電における熱処理アルミナ上の帯電形成・進展特性

仲田祐希，小島寛樹，花井正広，浅利直紀，塩入哲，松尾和宏，早川直樹

平成26年電気学会全国大会

真空中の浮遊電極を介する絶縁破壊過程に関する実験的考察

孔飛，中野裕介，小島寛樹，木村俊則，月間満，早川直樹

平成26年電気学会全国大会

セラミックスの大気中熱処理が真空中のセラミックス表面の発光開始電圧に与える影響

浅利直紀，塩入哲，佐藤純一，松尾和宏，小島寛樹，花井正広，早川直樹

平成26年電気学会全国大会

真空中沿面フラッシオーバ進展過程における過渡帯電電荷量と放電進展条件

中野裕介，小島寛樹，土屋賢治，早川直樹

平成26年電気学会全国大会

液体窒素の絶縁破壊電界におけるサイズ効果の圧力・温度依存性

西町誠一郎，小島寛樹，花井正広，早川直樹

電気学会放電/誘電・絶縁材料/高電圧合同研究会 2014.1.23 電気学会電/誘電・絶縁材料/高電圧技術委員会

Inception Mechanism of Surface Flashover on Solid Insulator in Vacuum International conference

Y .Nakano, H. Kojima, N. Hayakawa, K. Tsuchiya, H. Okubo

International Symposium on EcoTopia Science 2013

Intelligent Grid Management System (IGMS) with Optimum Power Flow and Degradation Control of Power Apparatus International conference

K. Fukaya, K. Shinoda, H. Kojima, M. Hanai, H. Okubo, N. Hayakawa

International Symposium on EcoTopia Science 2013

Electrical Insulation Characteristics of Insulating Oil with Dispersed TiO₂ and ZnO Nanoparticles International conference

K. Sato, S. Hosomi, M. Hanai, H. Kojima, N. Hayakawa, H. Okubo

International Symposium on EcoTopia Science 2013

Spark Conditioning Effect on Multi-gap Electrode System in Vacuum International conference

Y. Otake, H. Kojima, N. Hayakawa, K. Hasegawa, H. Saito, M. Sakaki, H. Okubo

International Symposium on EcoTopia Science 2013

Initiation and Propagation Mechanism of Leader-type Breakdown in Air International conference

T. Kitamura, K. Hotta, H. Kojima, N. Hayakawa, K. Kobayashi, T. Kato, T. Rokunohe, H. Okubo

International Symposium on EcoTopia Science 2013

Electric Field Control for Gas Insulated Switchgear with Functionally Graded Materials (FGM) on Surface Conductivity International conference

J. Ishiguro, H. Kojima, M. Hanai, K. Kato, H. Okubo, N. Hayakawa

International Symposium on EcoTopia Science 2013

Influence of Needle Electrode Material and Shape on Electromagnetic Wave Radiation Characteristics of Partial Discharge in SF₆ Gas International conference

R. Mizuno, M. Hanai, H. Kojima, N. Hayakawa, M. Yoshida, H. Okubo

International Symposium on EcoTopia Science 2013

Current Limiting Characteristics of Superconducting Fault Current Limiting Cable (SFCLC) with Longitudinal Temperature Distribution International conference

T. Osawa, H. Kojima, M. Hanai, N. Hayakawa, H. Okubo

International Symposium on EcoTopia Science 2013

Partial Discharge Inception Characteristics of Rectangular Wires for Inverter-fed Motors International conference

T. Wakimoto, H. Kojima, M. Hanai, N. Hayakawa

International Symposium on EcoTopia Science 2013

真空中における突発的電子放出に起因する沿面フラッシオーバメカニズム

中野裕介，小島寛樹，土屋賢治，早川直樹

電気学会放電/開閉保護/高電圧合同研究会 2013.11.20 電気学会放電/開閉保護/高電圧技術委員会

Conditioning Process of Multi-gap Electrode System with Cu-Cr Rod Electrode in Vacuum International conference

Y. Otake, H. Kojima, N. Hayakawa, K. Hasegawa, H. Saito, M. Sakaki, H. Okubo

2nd International Conference on Electric Power Equipment - Switching Technology 2013.10.22 Nagoya University

Event date： 2013.10

Language：English Presentation type：Oral presentation (general)

Venue：Matsue Country：Japan

In order to clarify the characteristics of spark conditioning carried out in parallel at several parts of electrodes, we studied conditioning process in a multi-gap electrode system with two rod-plane electrodes in vacuum. The rod material and gap distance of one gap was kept to Cu-Cr (d=5 mm) in some multi-gap electrodes. On the other hand, the rod material and gap distance of the other gap were varied. As a result, the number of breakdowns till conditioning saturation of Cu-Cr rod in the multi-gap electrode system was less than that in the single-gap electrode system. These results suggest that charge activity occurs between electrodes even at the gap without breakdown, which can also contribute to the conditioning effect. © 2013 IEEE.

DOI： 10.1109/ICEPE-ST.2013.6804375

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000355108400088

Inception and Expansion Process of Surface Flashover on Solid Dielectrics in Vacuum International conference

Y. Nakano, H. Kojima, N. Hayakawa, K. Tsuchiya, H. Okubo

2nd International Conference on Electric Power Equipment - Switching Technology 2013.10.22 Nagoya University

Event date： 2013.10

Language：English Presentation type：Oral presentation (general)

Venue：Matsue Country：Japan

Surface discharge on solid insulator in vacuum, which is one of the most significant phenomena under high electric field, prevents vacuum circuit breaker and vacuum interrupter from applying to higher voltage level. To clarify the mechanism of surface flashover, we investigated the transiently-formed charge characteristics on alumina dielectrics in the development process of surface flashover, by using electrostatic probes behind alumina dielectrics and measuring the light emission image of flashover. As a result, we found out that charge distribution on the alumina dielectrics in the inception of surface flashover depends on the electron emission sites on the cathode and influences the expansion process of surface flashover in vacuum. © 2013 IEEE.

DOI： 10.1109/ICEPE-ST.2013.6804361

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000355108400074

Partial Discharge Characteristics and Mechanisms in Consideration of Charge Behavior on Alumina Dielectrics under AC Voltage in Vacuum International conference

H. Kojima, M. Ishida, N. Hayakawa, M. Hanai, J. Ikeda, T. Shioiri, H. Okubo

2nd International Conference on Electric Power Equipment - Switching Technology 2013.10.22 Nagoya University

Event date： 2013.10

Language：English Presentation type：Oral presentation (general)

Venue：Matsue Country：Japan

Partial discharge phenomenon, which is not breakdown but has a potential to lead breakdown, is sometimes observed under AC operating voltage application in vacuum. We aim to investigate the partial discharge on the insulator surface in vacuum by the measurement of charge behavior and light emission. The surface charge distribution reached a quasi-stationary state by repetition of the partial discharge. However, a sudden drastic change of surface charge distribution to another quasi-stationary state was also observed. This behavior could be explained by the sudden increase/decrease of electron emission from the cathode and the distribution of electric field due to the increase/decrease of accumulated surface charge by repetitive partial discharge under ac voltage. © 2013 IEEE.

DOI： 10.1109/ICEPE-ST.2013.6804363

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000355108400076

Development of Discharge Inception Simulator Considering Environmental Factors Using Advection-Diffusion Model International conference

A. Ohtake, K. Kobayashi, T. Kato, N. Yanagita, T. Rokunohe, H. Kojima, N. Hayakawa, H. Okubo

2nd International Conference on Electric Power Equipment - Switching Technology 2013.10.21 Nagoya University

Event date： 2013.10

Language：English Presentation type：Oral presentation (general)

Venue：Matsue Country：Japan

Insulation design with discharge simulation based on physical phenomena is used in designing electrical instruments to facilitate their miniaturization and obtain high insulation reliability. We developed a model to calculate partial discharge inception in a non-uniform air gap by considering how environmental factors, especially humidity, affect insulation performance. We upgraded the calculation model that built in the distribution of negative ion density using the amount of moisture on the electrodes. As a result, we can estimate the discharge inception voltage with high accuracy. Additionally, we attempted to extend the simulator for three-dimensional creep analysis. © 2013 IEEE.

DOI： 10.1109/ICEPE-ST.2013.6804308

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000355108400021

Dependence of TiO₂ and ZnO Nanoparticle Concentration on Electrical Insulation Characteristics of Insulating Oil International conference

M. Hanai, S. Hosomi, H. Kojima, N. Hayakawa, H. Okubo

2013 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2013.10.22 IEEE Dielectrics and Electrical Insulation Society

Event date： 2013.10

Language：English Presentation type：Poster presentation

Venue：Shenzhen Country：China

This paper presents that mineral oil and linear alkylbenzene with dispersed metal oxide nanoparticles were investigated to clarify the effect of nanoparticles on AC breakdown strength and relative permittivity characteristics. The materials of nanoparticles were selected at TiO2 (crystal structure of anatase and rutile) and ZnO. The nanoparticle concentrations of samples were prepared varying from 0 to 0.5 vol% into mineral oil or linear alkylbenzene by ultrasonic dispersion. AC (60 Hz) breakdown test was performed in a sphere-sphere electrode (diameter φ=12.5 mm, stainless steel) with gap length 2.0 mm, and also relative permittivity was measured at 60 Hz at room temperature. The breakdown strength increased by about 5 to 15% with the addition of nanoparticles. Relative permittivity increased with the addition of nanoparticles. With some combinations of insulating oil and nanoparticle, the measured relative permittivity agreed with the calculation with the random arranged model. But there are some combinations that the measured relative permittivity and the calculated one aren't coincident. These instructions give basic guidelines for illuminating their insulating characteristics. © 2013 IEEE.

DOI： 10.1109/CEIDP.2013.6748164

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000360957000191

Transition of Partial Discharge Inception Voltage under High Humidity for Enameled Rectangular Wires International conference

T. Wakimoto, H. Kojima, M. Hanai, N. Hayakawa

2013 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2013.10.23 IEEE Dielectrics and Electrical Insulation Society

Event date： 2013.10

Language：English Presentation type：Poster presentation

Venue：Shenzhen Country：China

In recent years, the miniaturization and greater power output of motors for EVs and HEVs have led to the higher drive voltages and the increased adoption of rectangular wire in coils (higher volume ratio). In order to ensure that the motor is electrically insulated, it is necessary to restrict partial discharges between coil wires, and to do this, it is important to reduce the potential difference between wires resulting from the operation of the inverter and to ensure that the coil wire has the proper coating thickness. However, the measurement of partial discharges between wires results in variability in the measured values depending on the environment and methods, which is a problem for the stringently controlled design of motor insulation. To clarify the factors affecting the partial discharge inception voltage (PDIV) between wires as well as the mechanism, the effect of ambient humidity, pre-discharge conditions on the PDIV between wires was analyzed using rectangular wire with a coating thickness of 40 μm and 160 μm. As a result, it was confirmed that when a pre-discharge is performed in a high-humidity environment, transient characteristics were displayed in which PDIV momentarily decreased and then increased. We performed discharge observations and electric field analysis. The results showed that in high-humidity environments, the pre-discharge causes moisture to adhere to the coating surface, resulting in the increase in surface conductivity, which influences the electric field strength in the air gap. © 2013 IEEE.

DOI： 10.1109/CEIDP.2013.6748317

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000360957000289

無鉄心超電導変圧器を用いた超電導限流/潮流制御装置（SPFCL）の限流特性

Cheng Wai Tatt，西町誠一郎，小島寛樹，花井正広，鹿島直二，長屋重夫，杉本重行，早川直樹

平成25年度電気関係学会東海支部連合大会

高湿度下のプレ放電がエナメル平角電線の部分放電開始電圧特性に与える影響

脇本亨，小島寛樹，花井正広，早川直樹

平成25年度電気関係学会東海支部連合大会

導電率傾斜機能材料（FGM）適用によるGISスペーサの電界制御

石黒純也，小島寛樹，花井正広，加藤克巳，早川直樹

平成25年度電気関係学会東海支部連合大会

サブクール液体窒素の絶縁破壊メカニズムおよびサイズ効果

西町誠一郎，小島寛樹，花井正広，早川直樹

平成25年度電気関係学会東海支部連合大会

TiO₂およびZnOナノ粒子分散による鉱油の電気絶縁特性向上

佐藤広治，小島寛樹，花井正広，早川直樹

平成25年度電気関係学会東海支部連合大会

真空中棒－平板電極系におけるスパークコンディショニング特性の放電電荷量依存性

大竹泰智，小島寛樹，長谷川光佑，斉藤仁，榊正幸，早川直樹

平成25年度電気関係学会東海支部連合大会

空気中不平等電界下におけるリーダ型絶縁破壊特性

北村卓也，小島寛樹，小林金也，加藤達朗，六戸敏昭，早川直樹

平成25年度電気関係学会東海支部連合大会

真空中沿面フラッシオーバの過渡帯電量と進展特性

中野裕介，小島寛樹，土屋賢治，早川直樹

平成25年度電気関係学会東海支部連合大会

IGMS（Intelligent Grid Management System）による電力機器の最適保守計画の導出精度

深谷皇紀，小島寛樹，花井正広，早川直樹

平成25年度電気関係学会東海支部連合大会

電磁波伝搬特性に基づくUHF法によるSF₆ガス中/空気中部分放電の識別

水野龍之介，小島寛樹，花井正広，吉田昌展，早川直樹

平成25年度電気関係学会東海支部連合大会

超電導限流ケーブル（SFCLC）の限流特性におけるケーブル入口温度依存性

大澤岳士，小島寛樹，花井正広，早川直樹

平成25年度電気関係学会東海支部連合大会

Influence of Longitudinal Temperature Distribution on Current Limiting Function of Superconducting Fault Current Limiting Cable (SFCLC) International conference

H. Kojima, T. Osawa, N. Hayakawa, M. Hanai, H. Okubo

11th European Conference on Applied Superconductivity

エナメル平角電線における高湿度下の部分放電開始電圧推移

脇本亨，花井正広，小島寛樹，早川直樹

平成25年電気学会基礎・材料・共通部門大会

真空中沿面フラッシオーバ開始時の放出電流特性

中野裕介，小島寛樹，土屋賢治，大久保仁，早川直樹

平成25年電気学会基礎・材料・共通部門大会

誘電率傾斜機能材料（FGM）によるGISスペーサ電界制御のフィラー粒径分布依存性

石黒純也，小島寛樹，花井正広，加藤克巳，大久保仁，早川直樹

平成25年電気学会基礎・材料・共通部門大会

空気中2次ストリーマ進展に及ぼす背後電界の影響

北村卓也，小島寛樹，早川直樹，小林金也，加藤達朗，六戸敏昭，大久保仁

平成25年電気学会基礎・材料・共通部門大会

TiO₂ナノ粒子分散による絶縁油の電気絶縁特性向上

佐藤広治，細見聡彦，小島寛樹，早川直樹，大久保仁

平成25年電気学会基礎・材料・共通部門大会

Intelligent Power Flow Control and Maintenance Technology by IGMS International conference

M. Hanai, H. Kojima, N. Hayakawa, H. Okubo

Cigré Study Committees B3/D1 Colloquium

Advanced Electrical Insulation Techniques for Higher Voltage Vacuum Interrupters International conference

H. Okubo, H. Kojima, K. Kato, N. Hayakawa, M. Hanai

Cigré Study Committees B3/D1 Colloquium

電力系統最適運用システム（IGMS）による機器状態と潮流との協調制御

深谷皇紀，篠田康生，小島寛樹，花井正広，大久保仁，早川直樹

平成25年電気学会電力・エネルギー部門大会

超電導限流ケーブル（SFCLC）の限流特性に及ぼす運転温度分布の影響

大澤岳士，小島寛樹，早川直樹，花井正広，大久保仁

平成25年電気学会電力・エネルギー部門大会

SF₆ガス中部分放電電流波形が放射電磁波の周波数特性に与える影響

水野龍之介，花井正広，小島寛樹，早川直樹，大久保仁，吉田昌展

平成25年電気学会電力・エネルギー部門大会

真空中スパークコンディショニングにおける電流制御による耐電圧向上

大竹泰智，小島寛樹，早川直樹，長谷川光佑，斉藤仁，榊正幸，大久保仁

平成25年電気学会電力・エネルギー部門大会

Optimum Power Flow and Degradation Control of Power Apparatus by CMD with Intelligent Grid Management System (IGMS) International conference

M. Hanai, K. Shinoda, H. Kojima, N. Hayakawa, H. Okubo

18th International Symposium on High Voltage Engineering

Electromagnetic Wave Radiation Characteristics of Partial Discharge Depending on Needle Electrode Material and Shape in SF₆ Gas International conference

R. Mizuno, H. Kojima, N. Hayakawa, M. Hanai, M. Yoshida, H. Okubo

18th International Symposium on High Voltage Engineering

Transition Mechanism from Pre-Discharge to Surface Flashover on Alumina Dielectrics in Vacuum International conference

Y. Nakano, H. Kojima, N. Hayakawa, K. Tsuchiya, H. Okubo

18th International Symposium on High Voltage Engineering

Leader Onset and Breakdown Mechanisms under Non-uniform Electric Field in Air International conference

H. Kojima, K. Hotta, N. Hayakawa, N. Yanagita, T. Kato, T. Rokunohe, H. Okubo

18th International Symposium on High Voltage Engineering

真空中沿面前駆放電から絶縁破壊への転移メカニズム

中野裕介，小島寛樹，早川直樹，土屋賢治，大久保仁

平成25年電気学会全国大会

SF₆ガス中における正極性特異部分放電発生条件

水野龍之介，小島寛樹，早川直樹，花井正広，吉田昌展，大久保仁

平成25年電気学会全国大会

GISスペーサ表面への局所傾斜導電性付与による電界低減効果

石黒純也，中野龍之，早川直樹，小島寛樹，花井正広，加藤克巳，大久保仁

平成25年電気学会全国大会

電力系統最適運用システム（IGMS）による機器診断に基づき系統信頼度を最大化する潮流制御

篠田康生，深谷皇紀，小島寛樹，早川直樹，花井正広，大久保仁

平成25年電気学会全国大会

空気中不平等電界下における2次ストリーマチャネル加熱型絶縁破壊機構

堀田克輝，北村卓也，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成25年電気学会全国大会

真空中アルミナ絶縁物沿面における交流部分放電現象と電荷挙動

石田真之，小島寛樹，花井正広，早川直樹，池田順一，塩入哲，大久保仁

平成25年電気学会全国大会

超電導ケーブルの電気絶縁技術における現状と課題

早川直樹，西町誠一郎，小島寛樹，花井正広，大久保仁

電気学会誘電・絶縁材料/電線・ケ－ブル合同研究会 2012.12.14 電気学会誘電・絶縁材料/電線・ケ－ブル技術委員会

Pressure and Temperature Dependence of Breakdown Characteristics of Sub-Cooled Liquid Nitrogen International conference

S. Nishimachi, N. Hayakawa, H. Kojima, M. Hanai, H. Okubo

2012 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2012.10.15 IEEE Dielectrics and Electrical Insulation Society

Event date： 2012.10

Language：English Presentation type：Poster presentation

Venue：Montreal Country：Canada

We investigated breakdown (BD) characteristics of sub-cooled liquid nitrogen (SLN2) using a sphere-to-plane electrode configuration for different pressures (0.1-0.3 MPa) and temperatures (65-77 K) of SLN2. BD voltage of SLN2 was measured repeatedly under ac voltage application. Experimental results quantitatively revealed that how much BD voltage increased with the increase in gap length and pressure, and with the decrease in temperature of SLN2. The gap length dependence of BD strength in SLN2 was analyzed and discussed in terms of number and size of bubbles in SLN2. In addition, we found that the decisive electric field factor (a) for BD was enhanced to 87-93 % of the maximum electric field strength in SLN2 against 82-83 % in LN2 under atmospheric boiling condition. © 2012 IEEE.

DOI： 10.1109/CEIDP.2012.6378814

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000316899800103

Influence of Local Degradation in Critical Current for Superconducting Fault Current Limiting Cable (SFCLC) International conference

H. Kojima, T. Osawa, F. Kato, N. Hayakawa, M. Hanai, H. Okubo

Applied Superconductivity Conference

Feasibility Study on Superconducting Power Flow Controller and Fault Current Limiter (SPFCL) International conference

N. Hayakawa, X. Mao, H. Kojima, M. Hanai, H. Okubo, N. Kashima, S. Nagaya, S. Sugimoto

Applied Superconductivity Conference

サブクール液体窒素の交流絶縁破壊メカニズム

西町誠一郎，小島寛樹，早川直樹，花井正広，大久保仁

平成24年度電気関係学会東海支部連合大会

空気中不平等電界下における２次ストリーマ到達条件

堀田克輝，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成24年度電気関係学会東海支部連合大会

真空中交流部分放電における電界分布の影響

石田真之，小島寛樹，花井正広，早川直樹，本間三孝，塩入哲，大久保仁

平成24年度電気関係学会東海支部連合大会

Cu-Cr棒電極を用いたマルチギャップ電極系における真空中インパルスコンディショニング特性

大竹泰智，小島寛樹，早川直樹，大久保仁，長谷川光佑，斉藤仁

平成24年度電気関係学会東海支部連合大会

真空中アルミナ絶縁物におけるインパルス沿面放電前駆放電の発光要因

中野裕介，小島寛樹，早川直樹，土屋賢治，大久保仁

平成24年度電気関係学会東海支部連合大会

TiO₂ナノ粒子分散による鉱油の電気絶縁特性向上に関する検討

細見聡彦，花井正広，小島寛樹，早川直樹，大久保仁

平成24年度電気関係学会東海支部連合大会

SF₆ガス中部分放電放射電磁波特性の金属異物材質依存性

水野龍之介，鈴木啓介，小島寛樹，早川直樹，花井正広，吉田昌展，大久保仁

平成24年度電気関係学会東海支部連合大会

Discrimination Technique of Streamer and Leader Type of Partial Discharge in SF₆ Gas Using UHF Method International conference

M. Hanai, K. Suzuki, R. Mizuno, H. Kojima, N. Hayakawa, H. Okubo

2012 IEEE International Conference on Condition Monitoring and Diagnosis 2012.9 School of Electrical Engineering and Informatics Bandung Institute of Technology, and Department of Electrical Engineering, Udayana University

Event date： 2012.9

Language：English Presentation type：Oral presentation (general)

Venue：Bali Country：Indonesia

The relationship between PD current pulse waveform at the PD source and radiated electromagnetic (EM) waveform is investigated, due to a metallic particle in SF6 gas. Leader discharge with the larger PD charge magnitude and the longer propagation length than those of streamer discharge can be an indicator of breakdown in SF6 gas. Simultaneous and synchronous measurement of PD current and EM signals in SF6 gas revealed that the streamer discharge and leader discharge could be discriminated in both time and frequency components, respectively. Compared with the streamer discharge in our experiment, the leader discharge is characterized by the longer rise/fall time. The partial discharge that has relatively little frequency components of 1500 MHz with electromagnetic waves can be presumed a leader discharge. This means that by applying the new technique, the streamer and leader types of PD in SF6 gas can be discriminated in UHF detecting system. © 2012 IEEE.

DOI： 10.1109/CMD.2012.6416437

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000316544800071

Optimum Power Flow Control Based on Power Apparatus Diagnosis by Intelligent Grid Management System (IGMS) International conference

M. Hanai, K. Shinoda, K. Wakaiki, H. Kojima, N. Hayakawa, H. Okubo

Event date： 2012.9

Language：English Presentation type：Oral presentation (general)

Venue：Bali Country：Indonesia

Transmission and distribution (T&D) system comprises a lot of aged apparatus, which may cause the decrease of the reliability owing to their deterioration. In order to maintain the high efficiency and high quality of T&D system, the authors have proposed 'Intelligent Grid Management System (IGMS)', which provides the optimum maintenance strategy and optimum power flow control. IGMS evaluates all of the events occurring in the T&D system as the cost. IGMS optimizes the power flow routes based on the failure risk, T&D loss, overload operation, life estimation of power apparatus, customer outage and so on. The impact of individual apparatus failure affects a whole T&D system performance such as blackout and secondary failure. The failure risk is also evaluated as cost by the product of the impact of the individual failure and the failure rate estimated by the condition monitoring diagnosis results of power apparatus. In this paper, the optimum power flow control based on the real-time diagnosis results of power apparatus is discussed. © 2012 IEEE.

DOI： 10.1109/CMD.2012.6416205

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000316544800132

Optimum Maintenance Plan of Electric Power Apparatus in Consideration of Maintenance History by Intelligent Grid Management System (IGMS) International conference

K. Shinoda, M. Hanai, K. Wakaiki, H. Kojima, N. Hayakawa, H. Okubo

Event date： 2012.9

Language：English Presentation type：Oral presentation (general)

Venue：Bali Country：Indonesia

Transmission and distribution (T&D) systemsare comprised of many aging apparatus, which impede the reliability and quality of the system. In order to maintain the high reliability and high quality of the T&D system, the authors have proposed 'Intelligent Grid Management System (IGMS)', which provides optimum maintenance strategy and optimum power flow control. In this paper, the optimum maintenance method and timing of the power apparatus in consideration of their maintenance history is discussed. The efficacy of the maintenance affects not only the performance at that time, but also the subsequent deterioration tendencies. The advanced IGMS with the consideration of the maintenance history is introduced to a T&D system model, and an optimum maintenance plan which minimizes the total cost in long-term perspective is derived. © 2012 IEEE.

DOI： 10.1109/CMD.2012.6416195

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000316544800124

真空中におけるインパルス沿面放電の前駆発光特性

中野裕介，小島寛樹，早川直樹，土屋賢治，大久保仁

平成24年電気学会基礎・材料・共通部門大会

真空中のセラミック表面の発光開始電圧に与える電極表面粗さの影響

浅利直紀，塩入哲，佐藤純一，本間三孝，小島寛樹，花井正広，早川直樹，大久保仁

平成24年電気学会基礎・材料・共通部門大会

Streamer Development Mechanism under Non-uniform Electric Field in Air International conference

K. Hotta, H. Kojima, N. Hayakawa, N. Yanagita, T. Kato, T. Rokunohe, H. Okubo

2012 International Conference on High Voltage Engineering and Application 2012.9.19 Chongqing Unviersity, Shanghai Jiaotong University, Mississippi State University

Event date： 2012.9

Language：English Presentation type：Oral presentation (general)

Venue：Shanghai Country：China

We discussed the development mechanism of the streamer channel leading to breakdown in a short air gap, by using an ultra-high speed measuring system. We clarified that the initiation of the secondary streamer leading to breakdown is attributed to an electron injection from the grounded plane electrode to the residual channel made by the primary streamer. In addition, by selective measurement of the discharge current waveform of single streamer channel leading to breakdown, the breakdown was verified to be dominated by the development of the secondary streamer and the subsequent Joule heating process focusing on the single streamer channel. © 2012 IEEE.

DOI： 10.1109/ICHVE.2012.6357036

Scopus

UHF電磁波の二周波数同時測定によるGIS部分放電診断

吉田昌展，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会電力・エネルギー部門大会

超電導電力機器におけるサブクール液体窒素の電気絶縁性能

西町誠一郎，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会電力・エネルギー部門大会

超電導限流ケーブル（SFCLC）の運転温度を考慮した限流特性の評価

大澤岳士，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会電力・エネルギー部門大会

空気中不平等電界下におけるインパルス絶縁破壊メカニズムの類別

堀田克輝，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成24年電気学会電力・エネルギー部門大会

SF₆ガス中不平等電界下における部分放電形態とUHF電磁波特性

水野龍之介，吉田昌展，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会電力・エネルギー部門大会

電力系統最適運用システム（IGMS）による機器の更新時期を考慮した最適潮流制御

篠田康生，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会電力・エネルギー部門大会

部分放電メカニズムに基づくGIS中金属異物形状同定手法

小島寛樹，鈴木隆文，早川直樹，花井正広，大久保仁

平成24年電気学会電力・エネルギー部門大会

Conditioning Characteristics of Multi-Gap Electrode System in Vacuum International conference

H. Kojima, Y. Otake, R. Nishimura, N. Hayakawa, K. Hasegawa, H. Saito, Y. Noda, H. Okubo

25th International Symposium on Discharges and Electrical Insulation in Vacuum 2012.9.3 Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences

Event date： 2012.9

Language：English Presentation type：Oral presentation (general)

Venue：Tomsk Country：Russian Federation

In order to clarify the characteristics of spark conditioning carried out in parallel at several parts of electrodes, we carried out conditioning experiment to use a multi-gap electrode system with multi-rod electrodes. As a result, we found that 50% breakdown voltage after conditioning saturation differed in the multi-gap electrode system from in a single gap electrode system. In addition, we found the different process to enhance the breakdown voltage in each electrode, by comparison to the single gap electrode system. © 2012 IEEE.

DOI： 10.1109/DEIV.2012.6412439

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000315985400006

Development Process of Impulse Surface Discharge in Vacuum International conference

Y. Nakano, H. Kojima, N. Hayakawa, K. Tsuchiya, H. Okubo

25th International Symposium on Discharges and Electrical Insulation in Vacuum 2012.9.4 Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences

Event date： 2012.9

Language：English Presentation type：Poster presentation

Venue：Tomsk Country：Russian Federation

We investigated the charge activity on alumina dielectrics in the development process of impulse surface discharge in vacuum. We clarified the charge activity in pre-discharge stage by ultra-high speed and high sensitivity measurement. We also measured the fast-framing images of surface flashover propagation synchronously with current waveforms. We found that the charge activities are classified into three stages, i.e. (I) pre-discharge, (II) surface flashover initiation, and (III) expansion, in the development process of surface discharge in vacuum. © 2012 IEEE.

DOI： 10.1109/DEIV.2012.6412467

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000315985400034

Charge Behavior and Partial Discharge Characteristics on Alumina Insulation under AC Voltage Application in Vacuum International conference

H. Kojima, M. Ishida, N. Hayakawa, M. Hanai, M. Homma, T. Shioiri, H. Okubo

25th International Symposium on Discharges and Electrical Insulation in Vacuum 2012.9.4 Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences

Event date： 2012.9

Language：English Presentation type：Poster presentation

Venue：Tomsk Country：Russian Federation

The charge behavior and partial discharge characteristics, which is not breakdown but has a potential to lead breakdown, at solid-composite system in vacuum can be a critical issue to be investigated, under ac operating voltage application. We investigate the partial discharge along an insulator surface in vacuum under AC voltage application by the measurement of the charging and the light emission. Under sudden AC high voltage application, the partial discharge along the alumina surface occurred at the peak voltage of the negative polarity. The partial discharge was initiated near the rod electrode and spread out over the whole alumina surface. By the analysis of electric field, the partial discharge and subsequent charging behavior on the alumina surface under AC voltage application was verified to be dominated by the distortion of electric field due to the negative charges accumulated on the alumina surface, and this distortion occurs at the period of decrease of negative applied voltage. © 2012 IEEE.

DOI： 10.1109/DEIV.2012.6412452

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000315985400019

Introduction Effect of Superconducting Power Flow Controller and Fault Current Limiter (SPFCL) in an Electric Power System

N. Hayakawa, X. Mao, H. Kojima, M. Hanai, N. Kashima, S. Nagaya, S. Sugimoto, H. Okubo

2012.6.22

Charge Behavior in Palm Fatty Acid Ester Oil (PFAE) / Pressboard Composite Insulation System under Voltage Application International conference

H. Kojima, N. Hayakawa, K. Kato, H. Okubo, K. Kawanishi, H. Koide

2012 IEEE International Symposium on Electrical Insulation 2012.6.12 IEEE Dielectrics and Electrical Insulation Society

Event date： 2012.6

Language：English Presentation type：Oral presentation (general)

Venue：San Juan Country：Puerto Rico

Palm Fatty Acid Ester Oil (PFAE) is one of the most promising environment-friendly biodegradable insulating oils for transformers. PFAE has significant advantages compared to other vegetable origin insulating oils and mineral oil, e.g. not only good insulation performance, high permittivity and high moisture tolerance, but also excellent cooling ability due to low kinematic viscosity, high thermal and chemical stability and high productivity. However, since the molecular content of PFAE is quite different from mineral oil, the fundamental charge behavior in PFAE has not been clarified yet. To clarify the temporal and spatial charge behavior in PFAE, we directly measured the electric field in oil duct model with PFAE / pressboard (PB) composite insulation system under dc voltage application and charged flow condition by using Kerr electrooptic field measurement technique. By the comparison of electric field and charge behavior characteristics with fresh and degraded mineral oil, we revealed that the essential mechanism of charge behavior is similar, but the difference in temporal and spatial characteristics is attributed to the higher intrinsic ion density and higher permittivity of PFAE than that of mineral oil.

DOI： 10.1109/ELINSL.2012.6251502

Scopus

CiNii Research

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000309221800085

真空中平行平板電極系におけるインパルスコンディショニングのギャップ長依存性

西村亮岐，小島寛樹，早川直樹，大久保仁

平成24年電気学会全国大会

SF₆中金属異物の部分放電電流波形と放射電磁波特性

鈴木啓介，水野龍之介，小島寛樹，早川直樹，花井正広，吉田昌展，大久保仁

平成24年電気学会全国大会

電力系統最適運用システム（IGMS）における機器診断に基づくリアルタイム潮流制御

若生海王，篠田康生，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会全国大会

電力系統最適運用システム（IGMS）による機器の将来状態推定に基づく最適潮流制御

篠田康生，若生海王，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会全国大会

電力系統最適運用システム（IGMS）における潮流制御が保守戦略へ与える影響

若生海王，篠田康生，北田裕樹，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会全国大会

電気光学Kerr効果による直流油浸複合絶縁系における抵抗率特性の検討

齋藤輝，仁木康平，小島寛樹，早川直樹，加藤克巳，大久保仁

平成24年電気学会全国大会

電力システムにおける超電導限流/潮流制御装置の潮流制御効果と限流・復帰特性

毛翔，小島寛樹，早川直樹，花井正広，大久保仁，鹿島直二，長屋重夫，杉本重幸

平成24年電気学会全国大会

超電導限流ケーブル（SFCLC）における臨界電流の局所的劣化の限流特性への影響評価

加藤史彦，大澤岳士，小島寛樹，早川直樹，花井正広，大久保仁

平成24年電気学会全国大会

275kV高温超電導ケーブルにおける複合段絶縁による高電圧化と誘電損失低減の両立

井上真彰，西町誠一郎，小島寛樹，早川直樹，花井正広，丸山修，大熊武，八木正史，大久保仁

平成24年電気学会全国大会

空気中不平等電界下における絶縁破壊に至るストリーマチャネルの進展メカニズム

堀田克輝，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成24年電気学会全国大会

真空中インパルス沿面における電荷挙動と放電進展過程

中野裕介，小島寛樹，早川直樹，土屋賢治，大久保仁

平成24年電気学会全国大会

真空中Cu-Cr電極系におけるインパルスコンディショニング過程と陰極表面状態

西村亮岐，大竹泰智，小島寛樹，早川直樹，大久保仁，佐藤裕昌，斉藤仁，野田泰司

平成24年電気学会全国大会

超電導限流ケーブルの開発に関する基礎研究

小島寛樹

パワーアカデミー研究助成 2012年成果報告会

Charge Activity on Alumina Dielectrics in Impulse Surface Flashover Propagation in Vacuum

Y. Nakano, H. Kojima, N. Hayakawa, K. Tsuchiya, H. Okubo

2012.3.9

Conditioning Characteristics of Multi-gap Electrode System in Vacuum

Y. Otake, R. Nishimura, H. Kojima, N. Hayakawa, K. Hasegawa, H. Saito, Y. Noda, H. Okubo

2012.3.9

Propagation Process of Impulse Surface Flashover on Alumina Dielectrics in Vacuum International conference

Y. Nakano, H. Kojima, N. Hayakawa, K. Tsuchiya, H. Okubo

International Symposium on EcoTopia Science 2011

Partial Discharge in Vacuum on Insulator Surface under AC Voltage Application International conference

H. Kojima, K. Aoki, N. Hayakawa, M. Hanai, M. Homma, T. Shioiri, H. Okubo

1st International Conference on Electric Power Equipment - Switching Technology 2011.10.25 China Electrotechnical Society and Chinese Society for Electrical Engineering

Event date： 2011.10

Language：English Presentation type：Oral presentation (general)

Venue：Xi’an Country：China

In high voltage vacuum apparatus, e.g. vacuum circuit breaker, a partial discharge phenomenon, which is not breakdown but has a potential to lead breakdown, is observed under AC voltage application. We investigate the partial discharge along an insulator surface in vacuum under AC voltage application by the measurement of the charging and the light emission. Under sudden AC high voltage application, the partial discharge along the alumina surface occurred at the peak voltage of both polarities, but mainly at the negative polarity. The partial discharge was initiated near the rod electrode and spread out over the whole alumina surface. The partial discharge and subsequent charging behavior on the alumina surface under AC voltage application was verified to be dominated by the distortion of electric field due to not only the negative charges on the alumina surface but also the decrease phase of applied AC voltage. © 2011 IEEE.

DOI： 10.1109/ICEPE-ST.2011.6123044

Scopus

Surface Flashover Propagation Process on Alumina Dielectrics under Impulse Voltage Application in Vacuum International conference

H. Kojima, Y. Nakano, N. Hayakawa, K. Tsuchiya, H. Okubo

1st International Conference on Electric Power Equipment - Switching Technology 2011.10.26 China Electrotechnical Society and Chinese Society for Electrical Engineering

Event date： 2011.10

Language：English Presentation type：Oral presentation (general)

Venue：Xi’an Country：China

We investigated the mechanism of surface flashover on alumina dielectrics under impulse voltage application in vacuum in order to enhance the electrical insulation performance of vacuum insulated power equipment. Through electrical and optical simultaneous measurements, we discussed propagation process of the surface flashover on alumina dielectrics in vacuum. We changed the incident angle (θ) of electric lines of force to the alumina surface, i.e. parallel and perpendicular as the main parameter. The different propagation process of the surface flashover was found and discussed by the difference of charging process due to an electron flight distance. © 2011 IEEE.

DOI： 10.1109/ICEPE-ST.2011.6123046

Scopus

Impulse Breakdown Mechanism Based on Discharge Propagation Process under Non-uniform Electric Field in Air International conference

K. Hotta, T. Iwata, H. Kojima, N. Hayakawa, N. Yanagita, T. Kato, T. Rokunohe, H. Okubo

2011 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2011.10.18 IEEE Dielectrics and Electrical Insulation Society

Event date： 2011.10

Language：English Presentation type：Poster presentation

Venue：Cancun Country：Mexico

In this paper, we aim to clarify the discharge mechanism leading to breakdown under non-uniform electric field in air, especially on the propagation process of discharge current channel. The discharge measurement was performed in a needle (φ1 mm)-plane electrode system with gap length g=15-100 mm in 0.1 MPa dry air under applying a positive impulse voltage. We observed discharge current waveform and fast-framing images of light emission with image intensifier controlled by a nanosecond pulse. We found out two types of breakdown mechanisms from streamer initiation to breakdown (BD); secondary streamer progress and leader progress. In addition, we investigated the transition region between both types of BD mechanism, focusing on the case of gap length (g=30 mm). Finally, we found that the secondary streamer propagation would dominae the formation process of the discharge channel and the mechanism leading to BD. Also, we found the criterion of impulse breakdown mechanism in air. © 2011 IEEE.

DOI： 10.1109/CEIDP.2011.6232712

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000399725600128

Power Flow Control in Consideration of Apparatus Aging Distribution and Failure Rate by Intelligent Grid Management System (IGMS)

K. Wakaiki, K. Shinoda, H. Kojima, N. Hayakawa, M. Hanai, H. Okubo

2011.9.29

超電導限流ケーブル（SFCLC）の限流・復帰特性の冷却構造依存性

加藤史彦，小島寛樹，早川直樹，花井正広，大久保仁

平成23年度電気関係学会東海支部連合大会

空気中不平等電界下のインパルス絶縁破壊における2次ストリーマ発生条件に関する検討

堀田克輝，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成23年度電気関係学会東海支部連合大会

機器診断を基に最適な潮流制御を行う電力系統最適運用システム（IGMS）

若生海王，篠田康生，小島寛樹，早川直樹，花井正広，大久保仁

平成23年度電気関係学会東海支部連合大会

電力機器の劣化推移を考慮した電力機器運用最適化システム（IGMS）による最適潮流制御

篠田康生，若生海王，小島寛樹，早川直樹，花井正広，大久保仁

平成23年度電気関係学会東海支部連合大会

半円ダイポールアンテナのスリット幅とアンテナ特性の関係

鈴木啓介，小島寛樹，早川直樹，花井正広，吉田昌展，大久保仁

平成23年度電気関係学会東海支部連合大会

275kV高温超伝導ケーブルにおける誘電損失低減に関する検討

井上真彰，小島寛樹，早川直樹，花井正広，大久保仁，丸山修，大熊武，八木正史

平成23年度電気関係学会東海支部連合大会

超電導限流/潮流制御装置による電力システムの潮流制御効果

毛翔，小島寛樹，早川直樹，花井正広，大久保仁，鹿島直二，長屋重夫，杉本重幸

平成23年度電気関係学会東海支部連合大会

真空中インパルス沿面放電進展過程の絶縁物上電界分布依存性

中野裕介，小島寛樹，早川直樹，土屋賢治，大久保仁

平成23年電気学会基礎・材料・共通部門大会

湿度を考慮した気中部分放電開始の解析的検討

加藤達朗，柳田憲史，六戸敏昭，堀田克輝，小島寛樹，早川直樹，大久保仁

平成23年電気学会基礎・材料・共通部門大会

真空中インパルスコンディショニング過程におけるCu-Cr微細分散層の形成に関する検討

西村亮岐，小島寛樹，早川直樹，佐藤裕昌，斉藤仁，野田泰司，大久保仁

平成23年電気学会基礎・材料・共通部門大会

空気中不平等電界下における2次ストリーマ進展と導電路形成プロセス

堀田克輝，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成23年電気学会基礎・材料・共通部門大会

Current Limitation and Recovery Function for Superconducting Fault Current Limiting Transformer (SFCLT) International conference

N. Hayakawa, T. Kito, J. Himbele, H. Kojima, M. Hanai, H. Okubo

Superconductivity Centennial Conference 2011

Recent Progress in Electrical Insulation Techniques for HTS Power Apparatus International conference

N. Hayakawa, H. Kojima, M. Hanai, H. Okubo

Superconductivity Centennial Conference 2011

Superconducting Fault Current Limiting Cable (SFCLC) with Current Limiting and Recovery Function International conference

H. Kojima, F. Kato, N. Hayakawa, M. Hanai, H. Okubo

Superconductivity Centennial Conference 2011

Maintenance Optimization of Power Apparatus by Intelligent Grid Management System (IGMS) and Upgrading by Partial Maintenance International conference

M. Hanai, K. Wakaiki, Y. Suzuki, H. Kojima, N. Hayakawa, H. Okubo

CIGRE SC A2 & D1 Joint Colloquium 2011

Electrical Insulation and Discharge Characteristics at HVDC Polarity Reversal in Oil/Pressboard Composite Insulation System International conference

H. Kojima, H. Saito, N. Hayakawa, K. Kato, H. Okubo

CIGRE SC A2 & D1 Joint Colloquium 2011

電力系統最適運用システム（IGMS）における保守履歴を考慮した電力機器の最適保守計画

篠田康生，若生海王，小島寛樹，早川直樹，花井正広，大久保仁

平成23年電気学会電力・エネルギー部門大会

電力系統最適運用システム（IGMS）による機器劣化を考慮した最適潮流制御

若生海王，篠田康生，小島寛樹，早川直樹，花井正広，大久保仁

平成23年電気学会電力・エネルギー部門大会

Influence of Gap Length on Discharge Channel Propagation and Breakdown Mechanism in Air International conference

H. Kojima, K. Hotta, T. Iwata, N. Hayakawa, N. Yanagita, T. Kato, T. Rokunohe, H. Okubo

17th International Symposium on High Voltage Engineering

Identification of Insulation Defect by Sequential Measurement of Partial Discharge in GIS International conference

M. Yoshida, K. Suzuki, H. Kojima, N. Hayakawa, M. Hanai, H. Okubo

17th International Symposium on High Voltage Engineering

Correlation between UHF Electromagnetic Waveforms and Partial Discharge Current Waveforms in GIS International conference

K. Suzuki, M. Yoshida, H. Kojima, N. Hayakawa, M. Hanai, H. Okubo

17th International Symposium on High Voltage Engineering

Partial Discharge Characteristics for Delamination Defect of Epoxy Cast Resin Power Apparatus International conference

D.-E.A. Mansour, H. Kojima, N. Hayakawa, M. Hanai, H. Okubo

17th International Symposium on High Voltage Engineering

Charge Behavior in Palm Fatty Acid Ester Oil (PFAE) / Pressboard Composite Insulation System with Charged Oil Flow International conference

H. Saito, H. Kojima, N. Hayakawa, K. Kato, K. Kawanishi, H. Koide, H. Okubo

2011 IEEE International Conference on Dielectric Liquids 2011.6.27 SINTEF Energy Research, Norwegian University of Science and Technology

Event date： 2011.6

Language：English Presentation type：Poster presentation

Venue：Trondheim Country：Norway

Palm Fatty Acid Ester Oil (PFAE) is expected as one of the substitutes for mineral oil of transformers owing to not only the high biodegradation but also the good insulation performance. In this paper, the electric field strength and its time transition in PFAE/Pressboard composite insulation system-under charged oil flow were directly measured by using Kerr electro-optic technique. We found that the electric field was generated by space charges in PFAE and was temporally changed with charge behavior. By comparison with high charging mineral oil, we clarified that the feature of the charge behavior in PFAE was similar to that in the mineral oil, but the behavior of electric field was different due to the variation of electric properties such as permittivity, relaxing time and charge density. © 2011 IEEE.

DOI： 10.1109/ICDL.2011.6015445

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000295317700045

Discharge Mechanism at HVDC Polarity Reversal in Oil/Pressboard Composite Insulation System International conference

H. Kojima, H. Saito, N. Hayakawa, K. Kato, H. Okubo

2011 IEEE International Conference on Dielectric Liquids 2011.6.28 SINTEF Energy Research, Norwegian University of Science and Technology

Event date： 2011.6

Language：English Presentation type：Oral presentation (general)

Venue：Trondheim Country：Norway

At the instant of polarity reversal of HVDC, very high electric field was generated in oil because the applied electric field was superimposed by the electric field of accumulated charges on pressboard (PB). When the total electric field exceeded the breakdown electric field strength, breakdown discharge in oil gap and surface discharge on the PB occurred. In this paper, by electric field measurement using Kerr electro-optic technique and optical observation, breakdown discharge characteristics and mechanisms in oil / PB composite insulation system were investigated at polarity reversal voltage. We revealed that the surface discharge neutralizes the accumulated charges on PB. The above experiments were carried out for different PB arrangements and discussed the discharge characteristics under HVDC polarity reversal conditions were discussed. © 2011 IEEE.

DOI： 10.1109/ICDL.2011.6015443

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000295317700043

Technical Evaluation of Current Limitation and Recovery Characteristics for Superconducting Fault Current Limiting Transformer (SFCLT)

J. Himbele, T. Kito, H. Kojima, N. Hayakawa, M. Hanai, H. Okubo

2011.6.10

真空中アルミナ絶縁物上負極性インパルス沿面放電進展メカニズム

石田亜成，中野裕介，小島寛樹，早川直樹，土屋賢治，大久保仁

平成23年電気学会全国大会

電力系統最適運用システム（IGMS）における最適潮流制御に無効電力が与える影響

若生海王，鈴木陽太郎，篠田康生，小島寛樹，早川直樹，花井正広，大久保仁

平成23年電気学会全国大会

パームヤシ脂肪酸エステル（PFAE）/プレスボード複合絶縁系における帯電油流動時の油中電荷挙動

齋藤輝，小島寛樹，早川直樹，加藤克巳，小出英延，川西啓造，大久保仁

平成23年電気学会全国大会

伝導冷却SMESコイルモデルの部分放電開始特性

井上真彰，小島寛樹，早川直樹，花井正広，式町浩二，平野直樹，長屋重夫，大久保仁

平成23年電気学会全国大会

次世代電力システムにおける超電導限流/潮流制御装置の適用可能性

毛翔，小島寛樹，早川直樹，花井正広，大久保仁

平成23年電気学会全国大会

超電導限流ケーブル（SFCLC）の限流・復帰機能特性評価

加藤史彦，小島寛樹，早川直樹，花井正広，大久保仁

平成23年電気学会全国大会

超電導限流変圧器（SFCLT）の復帰特性評価

鬼頭豊明，ヒンブルジョン，小島寛樹，早川直樹，花井正広，大久保仁

平成23年電気学会全国大会

過冷却液体窒素中における超電導ケーブル絶縁モデルの部分放電開始特性

早川直樹，鵜飼泰之，小島寛樹，花井正広，大久保仁，丸山修，大熊武，八木正史

平成23年電気学会全国大会

SF₆ガス中インパルス放電進展過程におけるリーダ転移機構の考察

細井勇佑，鈴木隆文，小島寛樹，早川直樹，花井正広，大久保仁

平成23年電気学会全国大会

空気中におけるインパルス絶縁破壊前駆導電路の形成過程

堀田克輝，岩田健，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成23年電気学会全国大会

空気中インパルス絶縁破壊現象の高速放電測定と放電進展メカニズム

岩田健，堀田克輝，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成23年電気学会全国大会

真空中Cu-Cr電極コンディショニングにおける微細分散層形成プロセスに関する検討

西村亮岐，小島寛樹，早川直樹，佐藤裕昌，斉藤仁，野田泰司，大久保仁

平成23年電気学会全国大会

真空中交流電圧印加時における絶縁物沿面の部分放電メカニズム

青木圭太，小島寛樹，早川直樹，本間三孝，塩入哲，大久保仁

平成23年電気学会全国大会

真空中交流電圧印加時における絶縁物沿面の部分放電現象

小島寛樹，青木圭太，早川直樹，本間三孝，塩入哲，大久保仁

平成23年電気学会全国大会

真空中のセラミック表面での部分放電現象の調査

塩入哲，浅利直紀，佐藤純一，竹井義博，本間三孝，青木圭太，小島寛樹，大久保仁

平成23年電気学会全国大会

GIS中における部分放電電流波形とUHF放射電磁波の相関に関する検討

鈴木啓介，吉田昌展，小島寛樹，早川直樹，大久保仁

平成23年電気学会全国大会

電力系統最適運用システム（IGMS）における保守時期と保守費用対効果の関係

鈴木陽太郎，若生海王，篠田康生，小島寛樹，早川直樹，花井正広，大久保仁

平成23年電気学会全国大会

SF₆中交流部分放電と検出UHF電磁波との相関性の検討

鈴木隆文，岩田健，小島寛樹，早川直樹，花井正広，植田玄洋，岡部成光，大久保仁

平成23年電気学会全国大会

Conference Report on International Conference on Condition Monitoring and Diagnosis 2010 (CMD2010)

T. Takahashi, T. Okamoto, N. Hayakawa, H. Kojima

2011.3.5

Basic Study of Air Discharge Start Model and the Effect of Humidity

N. Yanagita, T. Kato, T. Rokunohe, T. Iwata, H. Kojima, N. Hayakawa, H. Okubo

2011.1.27

Feasibility Study on Superconducting Fault Current Limiting Cable (SFCLC) with Self-recovery Function

F. Kato, H. Kojima, N. Hayakawa, M. Hanai, H. Okubo

2011.1.20

Current Limiting and Recovery Characteristics of 2MVA Class Superconducting Fault Current Limiting Transformer (SFCLT)

T. Kito, H. Kojima, N. Hayakawa, M. Hanai, H. Okubo

2010.12.17

Recent Status and Future Perspective of Superconducting Fault Current Limiting Transformer (SFCLT)

N. Hayakawa, H. Kojima, M. Hanai, H. Okubo

23rd International Symposium on Superconductivity

Breakdown Characteristics in Oil/Pressboard-composite Insulation System at HVDC Polarity Reversal International conference

H. Okubo, T. Nara, H. Saito, H. Kojima, N. Hayakawa, K. Kato

2010 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2010.10 IEEE Dielectrics and Electrical Insulation Society

Event date： 2010.10

Language：English Presentation type：Oral presentation (general)

Venue：West Lafayette Country：United States

By using Kerr electro-optic technique, electric field in oil / pressboard (PB) composite insulation system, which is the typical insulation system of a transformer, was investigated at polarity reversal of HVDC voltage. When the applied voltage polarity was sharply reversed, the applied electric field was superimposed by the electric field of accumulated charges on PB, and very strong field appeared right after the polarity reversal. This could cause the discharge in the oil gap and on the PB surface. The critical value of the discharge initiation at the polarity reversal was verified to be determined by the sum of the applied electric field and the electric field of accumulated charges on PB. The discharge was observed by a high-speed video camera. It was clarified that the surface discharge on PB did not overlap with each other, which was explained by that the surface discharge could neutralize the charges on PB. ©2010 IEEE.

DOI： 10.1109/CEIDP.2010.5724003

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000398821400069

Improvement of Cu-Cr Electrode Surface under Impulse Voltage Conditioning in Vacuum International conference

H. Kojima, H. Yasukawa, R. Nishimura, H. Okubo, H. Sato, H. Saito, Y. Noda

2010 International Conference on High Voltage Engineering and Application 2010.10.11 Mississippi State University and Chongqing University

Event date： 2010.10

Language：English Presentation type：Oral presentation (general)

Venue：New Orleans Country：United States

As vacuum attracts attention from a viewpoint of high insulation performance and environmental-friendliness, vacuum circuit breakers (VCBs) are expected to develop into higher voltage level. In this paper, we discuss the relations between the surface state and the conditioning mechanism of Cu-Cr electrode during impulse voltage application process in vacuum. The experimental results showed that the deposited layer at the cathode surface was formed by the anode material due to the impulse voltage application process. We finally clarified and concluded that under impulse voltage application process, characteristics of the cathode surface are changing to those of the anode material, and anode material could determine the final states of conditioning process.

DOI： 10.1109/ICHVE.2010.5640856

Scopus

CiNii Research

Electric Field Optimization of Floating Electrode Configuration in Vacuum Interrupter International conference

H. Kojima, K. Suzuki, K. Kato, H. Okubo

2010 International Conference on High Voltage Engineering and Application 2010.10.11 Mississippi State University and Chongqing University

Event date： 2010.10

Language：English Presentation type：Oral presentation (general)

Venue：New Orleans Country：United States

For environment-friendly vacuum interrupter (VI), higher voltage operation and more compactness are required. From this point of view, and to enhance the electrical insulation performance of VI, it is needed to introduce the field optimization techniques. In this paper, we propose a new optimization technique for electrode configuration with floating potential in VI. We applied this optimization technique to the edge configuration of center shield in VI with considering the arrangement of grounded tank. Consequently, the maximum electric field strength decreased to 70% of non-optimized shape. From the results, we verified the effectiveness of the proposed automatic numerical optimization technique for the improvement of the insulation performance in high voltage vacuum insulated equipment. ©2010 IEEE.

DOI： 10.1109/ICHVE.2010.5640872

Scopus

Other Link： http://hdl.handle.net/2237/14457

Positive Streamer Propagation and Breakdown Characteristics in Non-uniform Air Gap International conference

T. Iwata, H. Kojima, N. Hayakawa, F. Endo, N. Yanagita, T. Kato, T. Rokunohe, H. Okubo

2010 International Conference on High Voltage Engineering and Application 2010.10.12 Mississippi State University and Chongqing University

Event date： 2010.10

Language：English Presentation type：Poster presentation

Venue：New Orleans Country：United States

Discharge phenomena in a needle-plane electrode in air were studied with nano-second time resolution by means of synchronous measurement of streak image, light intensity, discharge current and fast-framing image. When positive impulse voltage was applied, a primary streamer initiated from the needle tip and propagated to the grounded plane electrode. A secondary streamer initiated after the primary streamer arrived at the plane electrode. There are close relations between the applied voltage, the primary and the secondary streamer current and the initiation time of the secondary streamer. The breakdown can start when the secondary streamer have arrived at the plane electrode. Moreover, the time to breakdown becomes shorter with the increase in the secondary streamer current.

DOI： 10.1109/ICHVE.2010.5640749

Scopus

Other Link： http://hdl.handle.net/2237/14456

Optimization of environment-friendly electric energy systems from the integrated viewpoint of diagnosis, monitoring, operation and apparatus development

M. Hanai, F. Endo, H. Kojima, N. Hayakawa, H. Okubo

2010.9.29

気中放電における1次及び2次ストリーマ進展モデルの基礎検討

柳田憲史，加藤達朗，六戸敏昭，岩田健，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成22年電気学会基礎・材料・共通部門大会

Cu-Cr電極系における真空中インパルスコンディショニング過程と電極表面状態に関する検討

西村亮岐，小島寛樹，佐藤裕昌，斉藤仁，野田泰司，早川直樹，大久保仁

平成22年電気学会基礎・材料・共通部門大会

Optimum Strategy of Power System Maintenance and Operation with Intelligent Grid Management System (IGMS)

International Conference on Condition Monitoring and Diagnosis 2010

Charge Behavior in Palm Fatty Acid Ester Oil (PFAE) / Pressboard Composite Insulation System under Electrification Flow

H. Saito, T. Nara, K. Kato, H. Kojima, H. Zheng, H. Koide, H. Okubo

International Conference on Condition Monitoring and Diagnosis 2010

Partial Discharge Signal Evaluation of UHF Technique in Accordance with Current Pulse Waveform Measurement

M. Yoshida, K. Suzuki, H. Kojima, N. Hayakawa, M. Hanai, F. Endo, H. Okubo

International Conference on Condition Monitoring and Diagnosis 2010

Optimum Maintenance Strategies Based on Circuit Breaker Diagnoses for Total Cost Minimization of Electric Power System Operation

Y. Suzuki, K. Wakaiki, H. Kojima, N. Hayakawa, M. Hanai, F. Endo, H. Okubo

International Conference on Condition Monitoring and Diagnosis 2010

Particle-Initiated Partial Discharge Characteristics for GIS Diagnosis

K. Suzuki, M. Asai, H. Kojima, N. Hayakawa, F. Endo, M. Yoshida, H. Okubo

International Conference on Condition Monitoring and Diagnosis 2010

金属異物存在下におけるSF₆ガス中部分放電電流・放射電磁波スペクトル特性

鈴木啓介，吉田昌展，小島寛樹，早川直樹，遠藤奎将，花井正広，大久保仁

平成22年電気学会電力・エネルギー部門大会

遮断器の診断に基づく電力システムの最適保守戦略（IGMS）

鈴木陽太郎，若生海王，小島寛樹，早川直樹，遠藤奎将，花井正広，大久保仁

平成22年電気学会電力・エネルギー部門大会

超電導限流ケーブル（HTS-FCL Cable）の導入と限流・復帰に関する考察

加藤史彦，小島寛樹，早川直樹，花井正広，大久保仁

平成22年電気学会電力・エネルギー部門大会

超電導限流変圧器（SFCLT）の限流・復帰シミュレーション

鬼頭豊明，小島寛樹，早川直樹，花井正広，大久保仁

平成22年電気学会電力・エネルギー部門大会

電力システム最適運用（IGMS）による系統への影響を考慮した遮断器の最適保守

若生海王，鈴木陽太郎，小島寛樹，早川直樹，遠藤奎将，花井正広，大久保仁

平成22年電気学会電力・エネルギー部門大会

超電導限流ケーブル（HTS-FCL Cable）の限流特性に及ぼす臨界電流の不均一性の影響

加藤史彦，小島寛樹，早川直樹，花井正広，大久保仁

平成22年度電気関係学会東海支部連合大会

遮断器の部分保守による電力機器運用最適化システム（IGMS）の高度化

若生海王，鈴木陽太郎，小島寛樹，早川直樹，遠藤奎将，花井正広，大久保仁

平成22年度電気関係学会東海支部連合大会

超電導限流変圧器（SFCLT）における故障電流限流後の超電導復帰過程

鬼頭豊明，小島寛樹，早川直樹，花井正広，大久保仁

平成22年度電気関係学会東海支部連合大会

真空中平行平板電極系におけるインパルスコンディショニングの放電電荷量依存性

西村亮岐，小島寛樹，早川直樹，大久保仁

平成22年度電気関係学会東海支部連合大会

電力機器運用最適化システム（IGMS）における機器診断の効果

鈴木陽太郎，若生海王，小島寛樹，早川直樹，遠藤奎将，花井正広，大久保仁

平成22年度電気関係学会東海支部連合大会

油浸複合絶縁系における直流極性反転時の油中放電メカニズム

齋藤輝，小島寛樹，早川直樹，加藤克巳，大久保仁

平成22年度電気関係学会東海支部連合大会

極低温/真空/固体複合絶縁系における部分放電開始特性

井上真彰，小島寛樹，早川直樹，花井正広，式町浩二，平野直樹，長屋重夫，大久保仁

平成22年度電気関係学会東海支部連合大会

空気中絶縁破壊直前の超高速放電測定と放電進展メカニズム

岩田健，小島寛樹，早川直樹，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成22年度電気関係学会東海支部連合大会

SF₆ガス中金属異物の部分放電電流と放射電磁波のスペクトル相関

鈴木啓介，吉田昌展，小島寛樹，早川直樹，花井正広，大久保仁

平成22年度電気関係学会東海支部連合大会

Enhancement of Breakdown Strength by Microdischarge under Impulse Voltage Applications in Vacuum International conference

K. Aoki, R. Nishimura, H. Kojima, M. Homma, T. Shioiri, H. Okubo

24th International Symposium on Discharges and Electrical Insulation in Vacuum 2010.8.30 HTEE Institute for High-Voltage Technology and Electric Power Systems

Event date： 2010.8 - 2010.9

Language：English Presentation type：Poster presentation

Venue：Braunschweig Country：Germany

An investigation of charge behavior such as microdischarge under high electric field in vacuum is very important in order to enhance the electrical insulation performance of vacuum circuit breakers and vacuum interrupters (VCB/VI). This paper discusses the enhancement characteristics of breakdown strength by microdischarge under applying impulse voltage repeatedly and changing vacuum pressure. As a result, microdischarge which had pulsed current waveform became smaller with repeated constant peak voltage applications under 10^-6 Pa vacuum. In addition, microdischarge generation had the electrode conditioning effect to raise the breakdown voltage by reducing adsorption gas of the electrodes. Microdischarge having very small charge compared with that of breakdown has a possibility of drastic enhancement of breakdown strength in vacuum, as the non-breakdown conditioning technique.

DOI： 10.1109/DEIV.2010.5625863

Scopus

CiNii Research

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000287378600008

Development Mechanism of Impulse Surface Flashover on Alumina Dielectrics in Vacuum International conference

T. Ishida, H. Kojima, K. Tsuchiya, H. Okubo

24th International Symposium on Discharges and Electrical Insulation in Vacuum 2010.8.30 HTEE Institute for High-Voltage Technology and Electric Power Systems

Event date： 2010.8 - 2010.9

Language：English Presentation type：Poster presentation

Venue：Braunschweig Country：Germany

We investigated the development mechanism of impulse surface flashover on alumina ceramic insulator in vacuum. We measured the still image and framing image of fast developing surface flashover in synchronous with applied impulse voltage and current waveforms. The light emission transition in initiation of surface flashover was clarified. We found the dark area is formed around the cathode and conducting channel is formed from the anode in developing process of surface flashover in vacuum.

DOI： 10.1109/DEIV.2010.5625860

Scopus

CiNii Research

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000287378600023

Current Limiting and Recovery Characteristics of 2MVA Class Superconducting Fault Current Limiting Transformer (SFCLT) International conference

2010 Applied Superconductivity Conference

Progress in Development of Superconducting Fault Current Limiting Transformer (SFCLT) International conference

N. Hayakawa, H. Kojima, F. Endo, H. Okubo

Applied Superconductivity Conference

Feasibility Study on High Temperature Superconducting Fault Current Limiting Cable (HTS-FCL Cable) Using Flux Flow Resistance International conference

F. Kato, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

Applied Superconductivity Conference

Analysis of Current Limiting and Recovery Characteristics of Superconducting Fault Current Limiting Transformer (SFCLT) with YBCO Coated Conductors International conference

T. Kito, M. Kotari, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

Applied Superconductivity Conference

Current Limiting Characteristics of HTS Fault Current Limiting Cable (HTS-FCL Cable) Using Flux Flow Resistance

F. Kato, H. Kojima, N. Hayakawa, M. Hanai, H. Okubo

2010.6.10

Electrical Insulation Performance of Superconducting Coil Model for Conduction-cooled SMES

N. Inoue, H. Kojima, N. Hayakawa, M. Hanai, K. Shikimachi, N. Hirano, S. Nagaya, H. Okubo

2010.6.11

Optimization of Asset Management in High Voltage Substation Based on Equipment Monitoring and Power System Operation International conference

Y. Suzuki, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2010 IEEE International Symposium on Electrical Insulation 2010.6.9 IEEE Dielectrics and Electrical Insulation Society

Event date： 2010.6

Language：English Presentation type：Symposium, workshop panel (public)

Venue：San Diego Country：United States

This paper presents a new optimization approach of maintenance strategy for equipment in a transmission and distribution (T&D) system. In this approach, a present and future equipment performance is estimated by using monitoring data, and impacts of performance in each equipment on a whole T&D system are evaluated. By minimizing the impacts, suitable maintenance procedures and timing are derived. This approach is applied to a circuit breaker (CB) in an electric network, and its significance and usefulness are presented.

DOI： 10.1109/ELINSL.2010.5549579

Scopus

CiNii Research

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000287026500039

真空バルブ内電極の電界最適化自動計算における最適収束条件の検討

鈴木啓也，加藤克巳，小島寛樹，大久保仁

平成22年電気学会全国大会

機器診断に基づく遮断器の最適保守方法と電力システムへのインパクト

鈴木陽太郎，若生海王，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成22年電気学会全国大会

湿度を考慮した気中放電開始モデルの基礎検討

柳田憲史，加藤達朗，六戸敏昭，岩田健，小島寛樹，遠藤奎将，大久保仁

平成22年電気学会全国大会

空気中の放電進展特性に及ぼす酸素濃度と湿度の影響

岩田健，小島寛樹，早川直樹，遠藤奎将，柳田憲史，加藤達朗，六戸敏昭，大久保仁

平成22年電気学会全国大会

真空中微小電流による電極コンディショニングに関する検討

西村亮岐，青木圭太，安川英明，小島寛樹，大久保仁

平成22年電気学会全国大会

真空中インパルス電圧印加時における電極間微小電流とアウトガス特性

青木圭太，安川英明，小島寛樹，本間三孝，塩入哲，大久保仁

平成22年電気学会全国大会

真空中アルミナ絶縁物上インパルス沿面放電の進展過程

石田亜成，小島寛樹，土屋賢治，大久保仁

平成22年電気学会全国大会

高温超電導ケーブルにおける部分放電開始電界の絶縁材料依存性

鵜飼泰之，小島寛樹，遠藤奎将，早川直樹，市川裕士，藤原昇，八木政史

平成22年電気学会全国大会

超電導限流ケーブル（HTS-FCL Cable）における超電導線材の抵抗発生特性

加藤史彦，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成22年電気学会全国大会

2MVA級高温超電導限流変圧器（HTS-SFCLT）の限流・超電導復帰特性

神足将司，鬼頭豊明，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成22年電気学会全国大会

GIS内部絶縁物上異物による部分放電の時系列特性に関する検討

吉田昌展，鈴木啓介，浅井基希，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成22年電気学会全国大会

SF₆ガス中における絶縁物沿面付着金属異物の部分放電特性

浅井基希，鈴木啓介，吉田昌展，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成22年電気学会全国大会

Change of Partial Discharge Activity with Infiltrating SF₆ Gas at Electrode/Epoxy Delamination in GIS

D.A. Mansour, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

フラックスフロー抵抗を用いた超電導限流ケーブル (HTS-FCL Cable) の適用可能性

小島寛樹，加藤史彦，早川直樹，遠藤奎将，大久保仁

平成22年電気学会全国大会 2010.3.17 電気学会

電力システムの総合経済性と信頼度に基づく変圧器の最適保守方法

鈴木陽太郎，若生海王，小島寛樹，早川直樹，遠藤奎将，大久保仁

電気学会誘電・絶縁材料/電線・ケ－ブル合同研究会 2010.2.12 電気学会誘電・絶縁材料/電線・ケ－ブル技術委員会

Current Limiting and Recovery Characteristics of 2 MVA Class Superconducting Fault Current Limiting Transformer (HTS-SFCLT)

M. Kotari, T. Kito, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2010.1.25

Basic study on influence of insulation arrangement on electric field distribution under DC and polarity reversal condition

S. Iitsuka, H. Kojima, F. Endo, H. Okubo

2009.12.18

Development of Superconducting Fault Current Limiting Transformer (HTS-SFCLT)

M. Kotari, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2009.12.18

Study on Breakdown Mechanism in Non-uniform Gap in Air by Ultra-high Speed Measurement

T. IwataI, H. Kojima, N. Hayakawa, F. Endo, H. Okubo, N. Yanagita, T. Kato, T. Rokunohe

2009.11.20

Improvement of Accuracy for Insulation Diagnosis in GIS by Simultaneous Measurement of Partial Discharge Current Waveform and UHF Signal

M. Yoshida, M. Asai, F. Endo, N. Hayakawa, H. Kojima, H. Okubo

2009.11.20

Small Current Characteristics under Impulse Voltage Applications in Vacuum

K. Aoki, H. Yasukawa, H. Kojima, M. Homma, T. Shioiri, H. Okubo

2009.11.20

SF₆ガス中金属異物の部分放電パルスと放射UHF電磁波との相関

浅井基希，鈴木啓介，小島寛樹，早川直樹，遠藤奎将，吉田昌展，大久保仁

2009年度放電学会年次大会

真空中アルミナ絶縁物上帯電が沿面放電経路に与える影響

石田亜成，小島寛樹，土屋賢治，大久保仁

2009年度放電学会年次大会

空気中ストリーマ放電の進展特性および絶縁破壊メカニズムの検討

岩田健，小島寛樹，早川直樹，遠藤奎将，柳田憲史，加藤達朗，六戸敏昭，大久保仁

2009年度放電学会年次大会

Partial Discharge Detection at Delamination of Electrode/Epoxy Interface in GIS Spacers International conference

D.A. Mansour, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2009 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2009.10 IEEE Dielectrics and Electrical Insulation Society

Event date： 2009.10

Language：English Presentation type：Oral presentation (general)

Venue：Virginia Beach Country：United States

Partial Discharge (PD) measurements are very promising for insulation condition monitoring in Gas Insulated Switchgears (GISs). However, for accurate PD detection and diagnosis, there is a need for better understanding of physical mechanisms behind PD activity. Accordingly, we have been investigating the PD characteristics and associated mechanisms for electrode/epoxy delamination of GIS spacers as one of the most serious defects in GIS. The gas pressure inside delamination usually changes from sub-atmospheric pressure, just after delamination initiates, to filled SF6 gas pressure in the GIS tank, after SF6 gas permeates into the delamination area. Therefore, in this paper, the PD activity at different gas pressures, from 0.02 MPa to 0.4 MPa, is acquired. The relative PD generation rate and its phase appearance are analyzed at different pressures and then discussed from the viewpoint of PD mechanism and PD detection. Experimental results show that, with increasing pressure, the peak of the PD generation rate shifts from around zero crossing like void-type discharge to around a peak of ac voltage, before PD pulses vanish at high pressure for the applied electric field stress. The obtained results could be useful for delamination diagnosis in GIS spacers. © 2009 IEEE.

DOI： 10.1109/CEIDP.2009.5377864

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000279096900050

UHF Technique and Current Pulse Waveform Analysis for Partial Discharge Measurement International conference

H. Okubo, F. Endo, N. Hayakawa, H. Kojima, M. Yoshida, K. Uchida

CIGRE SC D1 Colloquium

Development of 2 MVA Class Superconducting Fault Current Limiting Transformer (SFCLT) with YBCO Coated Conductors International coauthorship International conference

M. Kotari, K. Omura, H. Kojima, N. Hayakawa, F. Endo, M. Noe, H. Okubo

9th European Conference on Applied Superconductivity

Partial Discharge Activities under AC/Impulse Superimposed Voltage in LN₂/Polypropylene Laminated Paper Insulation System for HTS Cables International conference

N. Hayakawa, R. Yamaguchi, Y. Ukai, H. Kojima, F. Endo, H. Okubo

9th European Conference on Applied Superconductivity

真空バルブ中間シールドの電界最適化自動計算における収束性の検討

鈴木啓也，加藤克巳，小島寛樹，大久保仁

平成21年度電気関係学会東海支部連合大会

空気中における2次ストリーマの進展と破壊特性

岩田健，吉田聡，小島寛樹，早川直樹，遠藤奎将，加藤達朗，六戸敏昭，大久保仁

平成21年電気学会基礎・材料・共通部門大会

真空中インパルス電圧印加時における微小電流の発生特性

青木圭太，安川英明，小島寛樹，本間三孝，塩入哲，大久保仁

平成21年電気学会基礎・材料・共通部門大会

Gas Pressure Dependency of Partial Discharge Activity at Electrode/Epoxy Delamination in GIS Spacer

D.A. Mansour, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

真空中固体絶縁物上正極性帯電がインパルス沿面放電の進展に与える影響

石田亜成，加藤秀紀，小島寛樹，土屋賢治，大久保仁

平成21年度電気関係学会東海支部連合大会

真空中Cu-Cr電極のインパルスコンディショニング過程の定量的検討

安川英明，青木圭太，小島寛樹，大久保仁，佐藤裕昌，斉藤仁，野田泰司

平成21年度電気関係学会東海支部連合大会

SF₆ガス中金属異物の部分放電特性に及ぼす電極間微小ギャップの影響

浅井基希，小島寛樹，早川直樹，遠藤奎将，吉田昌展，大久保仁

平成21年度電気関係学会東海支部連合大会

2MVA級高温超電導限流変圧器（SFCLT）YBCOコイルの限流動作特性

神足将司，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成21年度電気関係学会東海支部連合大会

電力システムの最適保守に及ぼす需要規模の影響

鈴木陽太郎，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成21年度電気関係学会東海支部連合大会

Leader Discharge Development and Breakdown Criteria under Non-uniform Electric Field in SF₆ International conference

H. Kojima, S. Yoshida, T. Iwata, N. Hayakawa, F. Endo, H. Okubo

16th International Symposium on High Voltage Engineering

Optimization of Asset Maintenance Strategies and Power Flow Operation Based on Condition Diagnoses International conference

F. Endo, R. Shiomi, Y. Suzuki, H. Kojima, N. Hayakawa, H. Okubo

16th International Symposium on High Voltage Engineering

Automatic Calculation of Optimized Electrode Configuration in Vacuum Interrupter International conference

K. Suzuki, K. Kato, H. Kojima, H. Okubo

16th International Symposium on High Voltage Engineering

HVDC機器の運転条件下における電界分布に対する絶縁物配置効果

飯塚伸介，小島寛樹，遠藤奎将，大久保仁

平成21年電気学会電力・エネルギー部門大会

電力システムへの故障インパクトを考慮した開閉装置の保守最適化

鈴木陽太郎，塩見僚，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成21年電気学会電力・エネルギー部門大会

SF₆ガス中部分放電特性に及ぼすフロート金属異物の影響とその識別

浅井基希，小島寛樹，早川直樹，遠藤奎将，吉田昌展，内田克己，大久保仁

平成21年電気学会電力・エネルギー部門大会

Optimized Asset Management of High Voltage Substations and Power Network Operation Based on Equipment Performance International conference

F. Endo, R. Shiomi, Y. Suzuki, H. Kojima, N. Hayakawa, H. Okubo

Cigré 6th Southern Africa Regional Conference and Joint Colloquium of CIGRE Study Committees A2(Transformers)-A3(High Voltage Equipment)-B3(Substations)

Influence of Accumulated Surface Charges on Partial Discharge Activity at Micro Gap Delamination in Epoxy GIS Spacer International conference

D. A. Mansour, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

9th International Conference on Properties and Applications of Dielectric Materials 2009.7.21 Harbin University of Science and Technology

Event date： 2009.7

Language：English Presentation type：Oral presentation (general)

Venue：Harbin Country：China

In epoxy spacers in Gas Insulated Switchgear (GIS) under operating thermal or mechanical stresses, delamination would be initiated at electrode/epoxy interface leading to partial discharge (PD) activity. In this paper, PD activity for delamination at electrode/epoxy interface in SF6 gas is measured and analyzed to clarify the effect of accumulated charges on the epoxy surface. The delamination gap length considered in this paper is 50 mum. The moment of delamination initiation in GIS is successfully simulated by applying sudden voltage to the electrode setup. The main results show that the charge accumulation has great effect on the PD generation rate. This effect is different between negative and positive PD as a result of the difference in initial electron generation mechanism. The measurement of surface potential and the change in PD inception voltage after PD activity enable to estimate the accumulated charge polarity. Consequently, the role of charge accumulation in PD activity is proposed based on the change in local electric field inside the delamination gap.

DOI： 10.1109/ICPADM.2009.5252341

Scopus

CiNii Research

HTS Fault Current Limiting Transformer (SFCLT) International coauthorship International conference

N. Hayakawa, H. Kojima, F. Endo, H. Okubo, M. Noe

CIGRE Workshop on Test Techniques and Procedures for HTS Power Applications

Electrical Insulation Test Techniques for HTS Power Equipment International conference

H. Okubo, N. Hayakawa, F. Endo, H. Kojima

CIGRE Workshop on Test Techniques and Procedures for HTS Power Applications

名古屋大学におけるSMES研究 Invited

小島寛樹

低温工学協会第4回材料研究会

発光スペクトル解析によるSF₆ガス中リーダ放電進展メカニズムの検討

小島寛樹，吉田聡，岩田健，早川直樹，遠藤奎将，大久保仁

平成21年電気学会全国大会

高ガス圧SF₆中におけるリーダ放電進展特性

吉田聡，岩田健，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成21年電気学会全国大会

Temporal Change of Partial Discharges for Delamination with Micrometer Gap Length at Electrode/Epoxy Interface in SF₆ Gas

D.A. Mansour, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

超電導限流変圧器（SFCLT）の開発

早川直樹，小島寛樹，遠藤奎将，大久保仁

平成21年電気学会全国大会

伝導冷却SMESコイルモデルの真空/固体複合絶縁系における電気絶縁特性

大村弘輝，早川直樹，小島寛樹，遠藤奎将，平野直樹，長屋重夫，大久保仁

平成21年電気学会全国大会

2MVA級高温超電導限流変圧器（HTc-SFCLT）の設計・製作

早川直樹，神足将司，大村弘輝，小島寛樹，遠藤奎将，大久保仁

平成21年電気学会全国大会

高温超電導ケーブルモデルにおける交流/インパルス重畳電圧印加時の部分放電特性

山口竜太郎，鵜飼泰之，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成21年電気学会全国大会

HVDC機器における新しい電界最適化技術に関する基礎的検討

飯塚伸介，小島寛樹，遠藤奎将，大久保仁

平成21年電気学会全国大会

電力システムの総合経済性を考慮した遮断器の最適保守方法

塩見僚，鈴木陽太郎，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成21年電気学会全国大会

SF₆ガス中インパルス不平等電界下における絶縁破壊メカニズムの検討

吉田聡，岩田健，小島寛樹，早川直樹，遠藤奎将，大久保仁

電気学会放電/誘電・絶縁材料/高電圧合同研究会

Influence of Accumulated Surface Charges on Time Transition of Partial Discharge Parameters for Micro Gap Interface in Gas Insulated Switchgear

D.-E. A. Mansour, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

背後電界の影響を考慮したSF₆ガス中インパルス絶縁破壊特性

吉田聡，岩田健，小島寛樹，早川直樹，遠藤奎将，大久保仁

2008年放電学会年次大会

Partial Discharge Characteristics for Small Gap of Electrode/Epoxy Interface in SF₆ Gas International conference

D.-E. Mansour, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2008 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2008.10.28 IEEE Dielectrics and Electrical Insulation Society

Event date： 2008.10

Language：English Presentation type：Poster presentation

Venue：Québec City Country：Canada

To achieve a safe operation of Gas Insulated Switchgears (GISs), the reliability of electrical insulation is one of the fundamental importance. For this respect, there is an urgent need for better understanding of partial discharge (PD) mechanisms at different locations in GIS. In the current work, the PD inception characteristics at electrode/epoxy interface at insulating spacer in GIS, which represents one of the most critical defects in GIS, are obtained and investigated with different gap lengths, 50-500 μm. Partial discharge inception voltage (PDIV) and electric field (PDIE) are measured and analyzed regarding PD inception mechanism in SF6 gas. Also the dependence of PDIV on repetitive number of PD pulses is obtained and discussed from the viewpoint of accumulated charge on the epoxy surface. © 2008 IEEE.

DOI： 10.1109/CEIDP.2008.4772884

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000265875100122

SF₆ガス中絶縁破壊に至るリーダ放電の測定

吉田聡，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年電気学会電力・エネルギー部門大会

電力システムの総合経済性を考慮した変圧器の最適保守方法(2)

塩見僚，金光正樹，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年電気学会電力・エネルギー部門大会

SF₆ガス中リーダ放電進展に及ぼす背後電界の影響

吉田聡，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年度電気関係学会東海支部連合大会

液体窒素/積層テープ複合絶縁系におけるハイパスフィルタを用いたインパルス部分放電測定

山口竜太郎，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年度電気関係学会東海支部連合大会

極低温環境下における真空/固体複合絶縁系の基礎絶縁特性

大村弘輝，小島寛樹，早川直樹，遠藤奎将，平野直樹，長屋重夫，大久保仁

平成20年度電気関係学会東海支部連合大会

伝導冷却SMES用Bi2223/Agコイルにおける電流−電圧特性の温度依存性

陳シン，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年度電気関係学会東海支部連合大会

Partial Discharge Activity and Charge Accumulation for Electrode/Epoxy Interface with Micro Gap in SF₆ Gas

D.-E. Mansour, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

機器保守が送配電コスト・最適送電ルートに及ぼす影響

塩見僚，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年度電気関係学会東海支部連合大会

Dynamic Thermal Characteristics of HTS Coil for Conduction-cooled SMES International conference

H.Kojima, X.Chen, N.Hayakawa, F.Endo, H.Okubo

2008 Applied Superconductivity Conference

Current Limiting Characteristics of Parallel-connected YBCO Coated Conductors for High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) International coauthorship International conference

N. Hayakawa, K. Omura, H. Kojima, F. Endo, H. Okubo, M. Noe

2008 Applied Superconductivity Conference

電気の正体・おもしろ実験

小島寛樹

市民公開講座「電気でファッショナブルライフ、あなたも今日からエコロジスト！」（第5回）

Partial Discharge Inception Strength in a Full-scale HTS Cable Based on LN₂/Polypropylene Laminated Paper Insulation International conference

N. Hayakawa, R. Yamaguchi, H. Kojima, F. Endo, H. Okubo

2008 IEEE International Conference on Dielectric Liquids 2008.7 EHD group of the University of Poitiers

Event date： 2008.6 - 2008.7

Language：English Presentation type：Poster presentation

Venue：Poitiers Country：France

We have been discussing the partial discharge (PD) inception characteristics of liquid nitrogen (LN_2) / polypropylene (PP) laminated paper composite insulation system for high temperature superconducting (HTS) cables. Based on the volume effect on PD inception electric field strength (PDIE) with a parameter called SSLV (statistical stressed liquid volume), in this paper, we evaluated PDIE of a full-scale HTS cable sample. Experimental results revealed that PDIE of the full-scale HTS cable sample at atmospheric LN_2 pressure under AC voltage application was consistent with the minimum PDIE value in the previous experiments. These results verify that 17.4 kV_rms/mm obtained in this paper can be regarded as a criterion of PDIE in consideration of the volume effect for the practical insulation design of actual HTS cables.

DOI： 10.1109/ICDL.2008.4622518

Scopus

CiNii Research

Light Emission Spectrum Depending on Propagation of Partial Discharge in SF₆ International conference

S. Yoshida, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2008 IEEE International Symposium on Electrical Insulation 2008.6.9 IEEE DEIS

Event date： 2008.6

Language：English Presentation type：Poster presentation

Venue：Vancouver Country：Canada

An understanding of mechanism of partial discharge (PD) in SF_6 gas is critical for diagnosis of PD in electric power equipment. Moreover, analysis of PD mechanism contributes to the optimization of the design of electric power applications. For these reasons, we study in detail about PD mechanism by measuring light emission spectrum of PD in SF_6 gas. In this paper, under an application of lightning impulse voltage in needle-plane electrodes, we have measured light emission spectrum of leader discharge. As the result, we have found out the light emission of long wavelength above 560nm in leader discharge, and the light emission above 560nm is emitted in the streamer head generated at the tip of the leader channel and radiated from dissociation products depending on the step propagation of leader discharge. These results suggest that we can diagnose the PD propagation in SF_6 gas and estimate the risk of breakdown (BD) by measuring PD light emission spectrum in electric power equipment. There are possibilities to contribute to enhance performance of the diagnosis technique in gas insulated power equipment.

DOI： 10.1109/ELINSL.2008.4570350

Scopus

CiNii Research

Optimization of Asset Management and Power System Operation Based on Equipment Performance International conference

F. Endo, M. Kanamitsu, R. Shiomi, H. Kojima, N. Hayakawa, H. Okubo

2008 International Conference on Condition Monitoring and Diagnosis 2008.4.23 Beijing Area Major Laboratory of High Voltage & EMC, North China Electric Power University

Event date： 2008.4

Language：English Presentation type：Poster presentation

Venue：Beijing Country：China

Odern T&D system has the issues about economical aspects, aged equipment, reliability etc. To solve these issues, equipment should be maintained optimally and the T&D system should be operated based on the present performance of equipment. For realization of these purposes, Intelligent Grid Management System (IGMS) was proposed and its basic functions are being investigated. In this paper, failure modes of a T&D system were chronologically simulated using Monte Carlo method, and all events occurred by failures in a T&D system were evaluated as cost with nonlinear programming. The expected T&D cost was calculated by repeating these procedure many times. By minimizing the expected T&D cost, the most optimum maintenance strategies of circuit breakers and transformers were derived quantitatively.

DOI： 10.1109/CMD.2008.4580356

Scopus

Other Link： http://hdl.handle.net/2237/11798

Dependence of Partial Discharge Characteristics at Spacer Surface on Particle Size in SF₆ Gas Insulated System International conference

N. Hayakawa, T. Okusu, K. Nishizawa, H. Kojima, F. Endo, M. Yoshida, K. Uchida, H. Okubo

2008 International Conference on Condition Monitoring and Diagnosis 2008.4.22 Beijing Area Major Laboratory of High Voltage & EMC, North China Electric Power University

Event date： 2008.4

Language：English Presentation type：Oral presentation (general)

Venue：Beijing Country：China

A metallic particle appeared in a gas insulated switchgear (GIS) sometimes adheres on a solid spacer surface. If the adhered metallic particle is exposed to a surge high voltage, a breakdown (BD) may be induced. Therefore, it is eagerly demanded to diagnose its risk correctly under the service voltage by partial discharge (PD) measurement. In this paper, particle-initiated surface PD characteristics were systematically studied in 0.4 MPa SF6 gas by changing the sizes of particles. PD inception voltage (PDIV), temporal change of PD current and the PD pulse number were analyzed in detail. Furthermore, comparing with PD characteristics of particles in a gas gap, the influence of the solid insulator on the PD characteristics was clarified. It was found out that PD characteristics greatly changed with time owing to electric charges deposited on a spacer surface. ©2007 IEEE.

DOI： 10.1109/CMD.2008.4580227

Scopus

Other Link： http://hdl.handle.net/2237/12060

Particle Size Identification in GIS by Ultra High Speed Measurement of Partial Discharge International conference

K. Nishizawa, T. Okusu, H. Kojima, N. Hayakawa, F. Endo, M. Yoshida, K. Uchida, H. Okubo

2008 International Conference on Condition Monitoring and Diagnosis 2008.4.22 Beijing Area Major Laboratory of High Voltage & EMC, North China Electric Power University

Event date： 2008.4

Language：English Presentation type：Poster presentation

Venue：Beijing Country：China

Gas insulated switchgear (GIS) is reliable equipment. However, when a metallic particle is in it, the insulation reliability of GIS sometimes reduces. Partial discharge (PD) measurement is usually performed to detect a metallic particle in GIS. After the PD detection, the criticality of PD must be estimated. For this purpose, identification of a particle size is very important. In this paper, every PD pulse of various particle sizes was measured sequentially with an ultra-high speed measuring system. And physical PD parameters were systematically analyzed. As a result, it was clarified that identification of the particle size was possible by considering the PD pulse number and current at positive and negative polarities. Finally, correspondence between electromagnetic wave emitted from PD and PD current was discussed.

DOI： 10.1109/CMD.2008.4580321

Scopus

CiNii Research

診断に基づく電力機器の将来性能の高精度予測方法の検討

塩見僚，金光正樹，小島寛樹，遠藤奎将，大久保仁

平成20年電気学会全国大会

高温超電導限流変圧器（HTc-SFCLT）用YBCO並列導体の限流特性

大村弘輝，伊藤智志，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年電気学会全国大会

電力システムの総合経済性を考慮した変圧器の最適保守方法

金光正樹，塩見僚，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年電気学会全国大会

SF₆ガス中における金属異物の部分放電電流パルスおよび電磁波特性に関する検討

西澤佳奈子，大楠崇司，小島寛樹，早川直樹，遠藤奎将，吉田昌展，内田克己，大久保仁

平成20年電気学会全国大会

SF₆ガス中リーダ放電進展に及ぼす解離生成物の影響

吉田聡，細井勇佑，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成20年電気学会全国大会

Novel Measurement and Analysis System for Investigation of Partial Discharge Mechanism in SF₆ Gas International conference

H. Kojima, N. Hayakawa, F. Endo, H. Okubo

12th International Middle-East Power System Conference 2008.3.13 South Valley University

Event date： 2008.3

Language：English Presentation type：Oral presentation (general)

Venue：Aswan Country：Egypt

An understanding of mechanism of partial discharge (PD) in SF6 gas is critical for diagnosis of PD in electric power equipment and contributes to the optimization of the design of electric power applications. However, for complexity of PD characteristics under non-uniform electric field, the mechanism of PD in SF6 is not comprehended enough. For this reason, we aim to reveal the PD mechanism by measuring current waveform, propagation characteristics and light emission of PD in SF6 gas and analyzing these data. For this purpose, we have developed excellent measurement and analysis techniques. For an analysis of PD under ac voltage application, not only PD waveforms but also PD propagation property is essential. We have constructed partial discharge current pulse waveform analysis (PD-CPWA) system. This system has enabled us to observe PD current sequentially at high speed and analyze the propagation of PD current pulse statistically. By the application of PD-CPWA system to diagnosis of PD activity due to the metallic particle in SF6, we could identify the particle type and size. On the other hand, for an analysis of PD under impulse voltage application, an ultra high-speed PD measurement by various methods is extremely important. In order to investigate the impulse PD mechanism spatially and temporally, the simultaneous measurement of current and light emission intensity waveforms, streak and still light emission images and temporal evolution of spectrum of PD light emission have been carried out. By using this synchronous ultra-high speed PD measurement system, we revealed the change of light emission from decomposition products depending on the step propagation of leader discharge. © 2008 IEEE.

DOI： 10.1109/MEPCON.2008.4562383

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000259262500089

Comparison of Partial Discharge Characteristics for Different Defect Types in SF₆ Gas Insulation System International conference

D. A. Mansour, T. Okusu, K. Nishizawa, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

12th International Middle-East Power System Conference 2008.3.13 South Valley University

Event date： 2008.3

Language：English Presentation type：Oral presentation (general)

Venue：Aswan Country：Egypt

The high reliability, less maintenance and compact size of Gas Insulated Switchgears (GISs) have made them the primary choice for many utilities. However, sometimes insulation defects inside GIS can be a serious threat to safe operation of GIS and can lead to costly disruption of supply. As insulation failure usually starts with partial discharge (PD) activity, this paper investigates the differences in PD characteristics in SF6 gas among different types of defects. The defect types considered in this study are particles in a gas gap, particles adhered on a spacer surface and spacer/electrode detachment. Different experiments were made for sequential PD measurements using the system of PD-Current Pulse Waveform Analysis (PD-CPWA). The PD phase characteristics, PD pulse number and PD current were analyzed for the different defect types. Also the ratio of voltage increment to phase increment at the next PD pulse appearance (Δu/ΔΦ pattern) was obtained and compared for each defect type. Experimental results show that correct identification of defects can be achieved based on considered PD characteristics. © 2008 IEEE.

DOI： 10.1109/MEPCON.2008.4562335

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000259262500041

機器信頼性に基づく電力システムの保守・運用の最適化

金光正樹，塩見僚，小島寛樹，早川直樹，遠藤奎将，大久保仁

電気学会誘電・絶縁材料/電線・ケーブル合同研究会 2008.2.19 電気学会誘電・絶縁材料/電線・ケーブル技術委員会

Variation of Light Emission Spectrum Depending on Partial Discharge Propagation in SF₆ Gas

S. Yoshida, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2007.11.26

Self-recovery Characteristics of High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductors International coauthorship

S. Ito, H. Kojima, N. Hayakawa, F. Endo, M. Noe, H. Okubo

International Symposium on EcoTopia Science 2007

Optimum Operation and Maintenance of Power Grid Based on Equipment Diagnoses

M. Kanamitsu, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

International Symposium on EcoTopia Science 2007

超高速PD測定によるGIS内異物サイズの識別

西澤佳奈子，大楠崇司，小島寛樹，早川直樹，遠藤奎将，吉田昌展，内田克己，大久保仁

2007年放電学会年次大会

SF₆ガス中部分放電におけるリーダ進展と発光スペクトルの関係

吉田聡，小島寛樹，早川直樹，遠藤奎将，大久保仁

2007年放電学会年次大会

高温超電導限流変圧器（2G HTc-SFCLT）における故障除去後の超電導復帰過程

伊藤智志，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年度電気関係学会東海支部連合大会

電力システムにおける機器故障率の送配電コストに及ぼす影響

金光正樹，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年度電気関係学会東海支部連合大会

SF₆ガス中部分放電におけるストリーマ/リーダ転移と発光エネルギーとの相関特性

吉田聡，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年度電気関係学会東海支部連合大会

実規模高温超電導ケーブルにおける部分放電開始電界の体積効果

山口竜太郎，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年度電気関係学会東海支部連合大会

Self-recovery Characteristics of High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductors International coauthorship International conference

H. Kojima, S. Itoh, N. Hayakawa, F. Endo, M. Noe, H. Okubo

8th European Conference on Applied Superconductivity

Quench-induced Partial Discharge Characteristics of HTS Cables International conference

N. Hayakawa, S. Ueyama, H. Kojima, F. Endo, Y. Ashibe, T. Masuda, M. Hirose

8th European Conference on Applied Superconductivity

機器統合型交直変換器用変圧器における電気絶縁設計に関する検討

小島寛樹，中野哲太郎，遠藤奎将，大久保仁

平成19年電気学会電力・エネルギー部門大会

実規模高温超電導ケーブルにおける部分放電開始特性

山口竜太郎，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年電気学会電力・エネルギー部門大会

高温超電導限流変圧器（2G HTc-SFCLT）における限流動作後の自己復帰特性

伊藤智志，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年電気学会電力・エネルギー部門大会

総合経済性に基づく送変電機器の最適保守戦略

金光正樹，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年電気学会電力・エネルギー部門大会

Partial Discharge Mechanism by Spectrum Measurement under Impulse Voltage Condition in SF₆ and Gas Mixtures International conference

H. Kojima, Y. Ohta, S. Yoshida, N. Hayakawa, F. Endo, H. Okubo

15th International Symposium on High Voltage Engineering

Partial Discharge Activity for Insulation System of High Temperature Superconducting Cables International conference

H. Okubo, N. Hayakawa, K. Sahara, R. Yamaguchi, H. Kojima, F. Endo

15th International Symposium on High Voltage Engineering

Application of Equipment Diagnoses to Operation and Management Planning of Power Grid International conference

F. Endo, M. Kanamitsu, H. Kojima, N. Hayakawa, H. Okubo

15th International Symposium on High Voltage Engineering

負性ガス中におけるインパルス部分放電特性と発光スペクトルの相関

吉田聡，小島寛樹，早川直樹，遠藤奎将，浜口昌弘，大久保仁

平成19年度電気学会基礎・材料・共通部門大会

Optimum Operation and Maintenance of Power Grid Based on Equipment Diagnoses International conference

F. Endo, M. Kanamitsu, H. Kojima, N. Hayakawa, H. Okubo

Power Tech 2007 2007.7.5 Energy Center of Swiss Federal Institute of Technology in Lausanne

Event date： 2007.7

Language：English Presentation type：Poster presentation

Venue：Lausanne Country：Switzerland

The concept of Intelligent Grid Management System (IGMS) was proposed to solve the issues concerning economics aspects, aged equipment, reliability etc. in modern transmission and distribution (T&D) systems. In IGMS, the patterns of system failure were chronologically simulated using the sequential Monte Carlo method, and the total T&D cost composed of T&D loss, overload cost, outage cost, maintenance cost, repair cost etc. was estimated with nonlinear programming. The minimization procedure of the total T&D cost was clarified. And the prospects of optimizing the maintenance strategy were obtained by calculating the total T&D cost for several maintenance methods. ©2007 IEEE.

DOI： 10.1109/PCT.2007.4538617

Scopus

Pressure Dependence of Partial Discharge Inception Characteristics under Quench Condition of HTS Cables

N. Hayakawa, S. Ueyama, H. Kojima, F. Endo, Y. Ashibe, T. Masuda, M. Hirose

2007.5.18

SMESにおける熱暴走の監視

小島寛樹

電気学会東海支部若手セミナー「超電導が拓くニューパラダイム（第3回）」

機器統合型直流変換器用変圧器における絶縁設計技術の基礎的検討

中野哲太郎，小島寛樹，遠藤奎将，大久保仁

平成19年電気学会全国大会

高温超電導ケーブルのクエンチ環境下における部分放電特性

上山進一，小島寛樹，早川直樹，遠藤奎将，芦辺佑一，増田孝人，廣瀬正幸

平成19年電気学会全国大会

発光スペクトル測定に基づく負性ガス中部分放電進展特性に関する検討

太田吉彦，吉田聡，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年電気学会全国大会

送配電コストを考慮した高経済な電力システム運用（IGMS）に関する検討(2)

金光正樹，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年電気学会全国大会

次世代超電導テープを用いた高温超電導限流変圧器の超電導復帰特性

伊藤智志，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年電気学会全国大会

高温超電導ケーブルモデルにおける部分放電特性の圧力依存性

佐原賢吾，山口竜太郎，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成19年電気学会全国大会

Evaluation of Partial Discharge Propagation Mechanism by Spectrum Measurement in Dielectric Gases

Y. Ohta, S. Yoshida, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2007.1.25

Operating Characteristics of High Temperature Superconducting Fault Current Limiting Transformer (2G HTc-SFCLT) with Coated Conductor

S. Ito, C. Kurupakorn, H. Kojima, N. Hayakawa, F. Endo, H. Okubo

2006.11.22

N₂/SF₆混合ガス中における部分放電進展と発光スペクトルとの相関特性

太田吉彦，吉田聡，小島寛樹，早川直樹，遠藤奎将，大久保仁

2006年放電学会年次大会

高温超電導ケーブルの絶縁構成における熱/電界複合ストレス下の部分放電特性

上山進一，小島寛樹，早川直樹，遠藤奎将，大久保仁

2006年放電学会年次大会

CO₂ガス中における金属異物による部分放電特性

大楠崇司，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成18年度電気関係学会東海支部連合大会

N₂/SF₆混合ガス中におけるリーダ放電進展とN₂スペクトルの発光強度比に関する検討

太田吉彦，吉田聡，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成18年度電気関係学会東海支部連合大会

液体窒素/エポキシ複合絶縁構成における沿面ストリーマ放電の進展特性

クルパコンチャチャヴァン，太田吉彦，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成18年度電気関係学会東海支部連合大会

高温超電導ケーブルの液体窒素／積層テープ複合絶縁構成における部分放電の時間推移特性

佐原賢吾，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成18年度電気関係学会東海支部連合大会

過冷却液体窒素／積層テープ複合絶縁構成における熱／電界複合ストレス下の部分放電特性

上山進一，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成18年度電気関係学会東海支部連合大会

N₂O混合ガスによる絶縁特性のシナジズム効果

小島寛樹，木下修，早川直樹，遠藤奎将，吉田昌展，小川達也，大久保仁

平成18年電気学会電力・エネルギー部門大会

送配電コストを考慮した高経済な電力システム運用に関する検討

遠藤奎将，小島寛樹，早川直樹，大久保仁

平成18年電気学会電力・エネルギー部門大会

高温超電導ケーブルのクエンチ環境を想定した電気絶縁特性

上山進一，小島寛樹，早川直樹，遠藤奎将，増田孝人，廣瀬正幸，大久保仁

平成18年電気学会電力・エネルギー部門大会

高温超電導ケーブルモデルにおける部分放電形態の推移特性

佐原賢吾，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成18年電気学会電力・エネルギー部門大会

Synergistic Effect in Electrical Insulation Characteristics of N₂O Gas Mixtures International conference

N. Hayakawa, O. Kinoshita, H. Kojima, F. Endo, M. Yoshida, T. Ogawa, H. Okubo

6th International Conference on Gas Discharges and their Applications

Partial Discharge Characteristics of Metallic Particle with Solid Insulator in SF₆ and CO₂ Gases International conference

H. Okubo, H. Kojima, N. Hayakawa, F. Endo

6th International Conference on Gas Discharges and their Applications

Thermal Runaway Characteristics of Bi2212 Coil for Conduction-cooled SMES International conference

H. Kojima, N. Hayakawa, S. Noguchi, F. Endo, H. Okubo, N. Hirano, S. Nagaya

Applied Superconductivity Conference

Electrical Insulation Characteristics of HTS Cables with Quench-induced Thermal Stress under High-Voltage Condition International conference

N. Hayakawa, S. Ueyama, H. Kojima, F. Endo, H. Okubo, T. Masuda, M. Hirose

Applied Superconductivity Conference

High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductors International coauthorship International conference

H. Okubo, C. Kurupakorn, S. Ito, H. Kojima, N. Hayakawa, F. Endo, M. Noe

Applied Superconductivity Conference

A study on thermal runaway detection and monitoring of HTS coil for conduction-cooled SMES

H. Kojima, S. Noguchi, N. Hayakawa, F. Endo, N. Hirano, S. Nagaya, H. Okubo

2006.5.15

Current Limiting Characteristics of Coated Conductor Tapes for High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT)

N. Hayakawa, C. Kurupakorn, S. Ito, H. Kojima, F. Endo, H. Okubo

2006.5.15

N₂O/CO₂/N₂混合ガスの準平等電界下における絶縁破壊特性

木下修，太田吉彦，小島寛樹，早川直樹，遠藤奎将，吉田昌展，小川達也，大久保仁

平成18年電気学会全国大会

伝導冷却SMES用Bi2212/Agコイルにおける熱暴走特性と熱伝導解析

野口真希，中野俊一，小島寛樹，早川直樹，遠藤奎将，平野直樹，長屋重夫，大久保仁

平成18年電気学会全国大会

高温超電導ケーブルの液体窒素/積層テープ複合絶縁構成における部分放電および絶縁破壊特性

佐原賢吾，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成18年電気学会全国大会

N₂/SF₆混合ガス中における部分放電発光スペクトルの高速時間分解測定

太田吉彦，木下修，小島寛樹，早川直樹，遠藤奎将，大久保仁，吉田昌展，小川達也

平成18年電気学会全国大会

高温超電導限流変圧器(HTc-SFCLT)用DyBCO超電導テープの限流特性

クルパコンチャチャヴァン，伊藤智志，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成18年電気学会全国大会

Synergy Effect in Electrical Insulation Characteristics of N₂O Gas Mixtures

O. Kinoshita, H. Kojima, N. Hayakawa, F. Endo, M. Yoshida, T. Ogawa, H. Okubo

2006.1.26

N₂OガスおよびN₂O混合ガスの絶縁特性

木下修，小島寛樹，早川直樹，遠藤奎将，吉田昌展，小川達也，大久保仁

2005年放電学会年次大会

固体およびガス中部分放電における部分放電電流パルス波形解析(PD-CPWA)の適用

杉森康啓，小島寛樹，早川直樹，遠藤奎将，大久保仁

2005年放電学会年次大会

高温超電導ケーブルの積層テープ絶縁構成における部分放電開始・進展および絶縁破壊特性

佐原賢吾，小島寛樹，早川直樹，遠藤奎将，大久保仁

2005年放電学会年次大会

Partial Discharge Inception and Breakdown Characteristics of LN₂/Polypropylene Laminated Paper Composite Insulation System for HTS Cables International conference

N. Hayakawa, K. Sahara, H. Kojima, F. Endo, H. Okubo

2005 IEEE Conference on Electrical Insulation and Dielectric Phenomena 2005.10 IEEE Dielectrics and Electrical Insulation Society

Event date： 2005.10

Language：English Presentation type：Poster presentation

Venue：Nashville Country：United States

A novel technique for partial discharge (PD) measurement and analysis (PD-CPWA: PD Current Pulse Waveform Analysis) is developed and introduced in this paper. The purpose of PD-CPWA is to elucidate PD mechanisms and physics in electrical insulating materials, focusing on the PD current pulse waveform and its time transition from PD inception to breakdown (BD). In this paper, PD-CPWA was applied to liquid nitrogen / polypropylene laminated paper composite insulation system for high temperature superconducting cables, and PD inception and propagation characteristics were obtained. Experimental results revealed that PD inception at the lower stress would mainly originated from micro gaps between PP laminated paper layers, and then PD activity could be developed also in butt gaps at the higher stress, and finally leading to BD. © 2005 IEEE.

DOI： 10.1109/CEIDP.2005.1560692

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000235927000086

CO₂ガスおよびSF₆ガス中における固体絶縁物上金属異物による部分放電特性

杉森康啓，早川直樹，小島寛樹，遠藤奎将，大久保仁

平成17年度電気関係学会東海支部連合大会

伝導冷却SMES用Bi2212/Ag HTSコイルにおける熱暴走特性

野口真希，クルパコンチャチャヴァン，小島寛樹，早川直樹，遠藤奎将，平野直樹，長屋重夫，大久保仁

平成17年度電気関係学会東海支部連合大会

高温超電導ケーブルの積層テープ絶縁構成における部分放電進展および絶縁破壊特性

佐原賢吾，小島寛樹，早川直樹，遠藤奎将，大久保仁

平成17年度電気関係学会東海支部連合大会

N₂O/CO₂/O₂混合ガスの準平等電界下における絶縁破壊特性

木下修，小島寛樹，早川直樹，遠藤奎将，吉田昌展，植田俊明，小川達也，大久保仁

平成17年度電気関係学会東海支部連合大会

Electrical and Thermal Characteristics of Bi2212/Ag HTS Coils for Conduction-cooled SMES International conference

N. Hayakawa, S. Noguchi, C. Kurupakorn, H. Kojima, N. Hirano, S. Nagaya, H. Okubo

7th European Conference on Applied Superconductivity

Optimization Design of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT) International coauthorship International conference

C. Kurupakorn, H. Kojima, N. Hayakawa, N. Kashima, S. Nagaya, M. Noe, K. P. Juengst, H. Okubo

7th European Conference on Applied Superconductivity

Dielectric-coating Effect in CO₂ and SF₆ Gases under Impulse Voltage Application International conference

N. Hayakawa, N. Koshino, O. Kinoshita, H. Kojima, F. Endo, M. Yoshida, T. Ueda, H. Okubo

14th International Symposium on High Voltage Engineering

Dielectric Characteristics of N₂O Gas and N₂O/CO₂ Gas Mixtures as SF₆ Substitutes International conference

O. Kinoshita, N. Koshino, H. Kojima, N. Hayakawa, F. Endo, M. Yoshida, T. Ueda, H. Okubo

14th International Symposium on High Voltage Engineering

N₂OおよびN₂O/CO₂混合ガスの不平等電界下における部分放電・絶縁破壊特性

木下修，越野尚人，小島寛樹，早川直樹，植田俊明，吉田昌展，大久保仁

平成17年電気学会電力・エネルギー部門大会

過冷却液体窒素中におけるBi2212/CuNi複合バルクコイルの限流特性

チャチャヴァンクルパコン，小島寛樹，早川直樹，鹿島直二，長屋重夫，大久保仁

平成17年電気学会電力・エネルギー部門大会

冷凍機伝導冷却HTSコイルにおける通電特性および熱的特性

野口真希，チャチャヴァンクルパコン，小島寛樹，早川直樹，平野直樹，長屋重夫，大久保仁

平成17年電気学会電力・エネルギー部門大会

高温超電導ケーブルの積層テープ絶縁構成における部分放電開始・進展特性

梛野晶樹，佐原賢吾，小島寛樹，早川直樹，大久保仁

平成17年電気学会電力・エネルギー部門大会

Technical Feasibility of Superconducting Fault Current Limiting Transformer in Future Electric Power Network

H. Kojima, C. Kurupakorn, N. Hayakawa, M. Goto, N. Kashima, S. Nagaya, H. Okubo

International Symposium on EcoTopia Science 2005

Impulse and AC PD Inception Characteristics of LN₂/Polypropylene Laminated Paper Composite Insulation System International conference

H. Okubo, M. Nagino, H. Kojima, N. Hayakawa, T. Takahashi, K. Yasuda

2005 IEEE International Conference on Dielectric Liquids 2005.6 Laboratório de Instrumentação e Física Experimental de Partículas

Event date： 2005.6 - 2005.7

Language：English Presentation type：Oral presentation (general)

Venue：Coimbra Country：Portugal

We discussed partial discharge (PD) inception characteristics of liquid nitrogen (LN2) / polypropylene (PP) laminated paper composite insulation system for high temperature superconducting (HTS) cables. In this paper, we measured PD inception characteristics under lightning impulse voltage application by both electrical and optical methods. The impulse PD inception characteristics were compared with those under ac voltage application, and the PD generation mechanisms were discussed. Experimental results revealed that PD detection sensitivity under lightning impulse voltage application reached as small as 6 pC. PD was verified to be generated not only inside the butt gap but also outside the butt gap under both lightning impulse and ac voltage applications. AE sensors could also be applied to PD measurement under ac voltage application. © 2005 IEEE.

DOI： 10.1109/ICDL.2005.1490117

Scopus

Other Link： https://www.webofscience.com/wos/woscc/full-record/WOS:000232829800103

Simulation of Current Limiting and Recovery Characteristics of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT)

C. Kurupakorn, H. Kojima, N. Hayakawa, F. Endo, N. Kashima, S. Nagaya, H. Okubo

2005.6.16

Partial Discharge Measurement by Acoustic Method in Laminated Paper Insulation System for HTS Cables

K. Sahara, M. Nagino, H. Kojima, N. Hayakawa, F. Endo, T. Takahashi, K. Yasuda, H. Okubo

2005.6.16

Electrical and Thermal Characteristics of Bi2212/Ag HTS Coil for Conduction-cooled SMES

S. Noguchi, C. Kurupakorn, H. Kojima, N. Hayakawa, F. Endo, N. Hirano, S. Nagaya, H. Okubo

2005.6.16

CO₂ガス中絶縁コーティング電極系における絶縁破壊電界の実効電界空間依存性

越野尚人，木下修，小島寛樹，早川直樹，植田俊明，大久保仁

平成17年電気学会全国大会

高温超電導ケーブル用液体窒素／積層テープ複合絶縁系におけるAEセンサを用いた部分放電測定

梛野晶樹，佐原賢吾，小島寛樹，早川直樹，後藤益雄，高橋俊裕，安田健次，大久保仁

平成17年電気学会全国大会

N₂OガスおよびN₂O/CO₂混合ガスの準平等電界下における絶縁破壊特性

木下修，越野尚人，小島寛樹，早川直樹，植田俊明，大久保仁

平成17年電気学会全国大会

Bi2212/CuNi複合バルクコイルの直並列接続時における抵抗発生特性

クルパコンチャチャヴァン，小島寛樹，早川直樹，後藤益雄，鹿島直二，長屋重夫，大久保仁

平成17年電気学会全国大会

SMES用伝導冷却Bi2212/Agコイルにおける臨界電流の温度依存性

野口真希，Chatchaval Kurupakorn，小島寛樹，早川直樹，後藤益雄，平野直樹，長屋重夫，大久保仁

平成17年電気学会全国大会

Temperature Dependence of Critical Current at 4.2K-55K of Conduction-cooled Bi2212/Ag Wires for SMES International conference

H. Kojima, S. Noguchi, C. Kurupakorn, N. Hayakawa, M. Goto, N. Hirano, S. Nagaya, H. Okubo

Applied Superconductivity Conference

Dielectric Characteristics and Electrical Insulation Design of HTS Cables International conference

N. Hayakawa, M. Nagino, H. Kojima, M. Goto, T. Takahashi, K. Yasuda, H. Okubo

Applied Superconductivity Conference

Recovery Characteristics after Current Limitation of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT) International coauthorship International conference

C. Kurupakorn, H. Kojima, N. Hayakawa, N. Kashima, S. Nagaya, M. Noe, K.-P. Juengst, H. Okubo

Applied Superconductivity Conference

高温超電導ケーブルの積層テープ絶縁構成におけるインパルス部分放電の高感度測定

梛野晶樹，小島寛樹，早川直樹，後藤益雄，高橋俊裕，安田健次，大久保仁

平成16年度電気関係学会東海支部連合大会

高温超電導限流変圧器（HTc-SFCLT）用Bi2212/CuNi複合バルクコイルの直列通電特性

クルパコンチャチャヴァン，小島寛樹，早川直樹，後藤益雄，鹿島直二，長屋重夫，大久保仁

平成16年度電気関係学会東海支部連合大会

伝導冷却SMES用Bi2212/Ag超電導線材の臨界電流特性

野口真希，Chatchaval Kurupakorn，小島寛樹，早川直樹，後藤益雄，平野直樹，長屋重夫，大久保仁

平成16年度電気関係学会東海支部連合大会

CO₂およびSF₆ガス中における絶縁コーティング電極の雷インパルス絶縁破壊特性

越野尚人，木下修，小島寛樹，早川直樹，植田俊明，大久保仁

平成16年度電気関係学会東海支部連合大会

高温超伝導限流変圧器（HTc-SFCLT）における限流後の復帰特性

クルパコンチャチャヴァン，早川直樹，小島寛樹，鹿島直二，長屋重夫，大久保仁

平成16年電気学会電力・エネルギー部門大会

Formation of Deep Potential Well and its Structural Transition in Small Tokamak Device International conference

Y. Fukuzawa, H. Kojima, T. Okada, N. Ohno, S. Takamura

31st EPS Conference on Plasma Physics

小型トカマクにおける深い電位井戸の形成と構造の遷移現象

福澤祐馬，小島寛樹，岡田享大，大野哲靖，高村秀一

第5回核融合エネルギー連合講演会

小型トカマク装置を用いた深い電位井戸の形成とその構造に関する研究

岡田享大，福澤祐馬，小島寛樹，大野哲靖，高村秀一

平成16年電気学会全国大会

Formation of Deep Potential Well by Electrode Biasing in Tokamak Device

Y. Fukuzawa, H. Kojima, T. Okada, N. Ohno, S. Takamura, T. Iguchi

2003.11.26

トカマク放電における深い電位バイアスによるトロイダルプラズマの構造変化のパラメータ依存性

岡田享大，小島寛樹，福澤祐馬，大野哲靖，高村秀一

平成15年度電気関係学会東海支部連合大会

小型トカマク装置における深い負電位井戸構造の形成とそのダイナミクス

小島寛樹，福澤祐馬，岡田享大，大野哲靖，高村秀一

日本物理学会2003年秋季大会

トカマクプラズマにおける深い電位井戸の形成とそのダイナミクス

福澤祐馬，小島寛樹，岡田享大，大野哲靖，高村秀一，井口哲夫

平成15年電気学会基礎・材料・共通部門（A部門）大会

トカマクプラズマにおける深い電位井戸の形成とそのダイナミクス

福澤祐馬，小島寛樹，岡田享大，大野哲靖，高村秀一，井口哲夫

第42回プラズマ若手夏の学校

Structural Formation and its Dynamics of Very Deep Negative Potential Well on Small Tokamak Device CSTN-IV International conference

H. Kojima, Y. Fukuzawa, T. Okada, T. Manabe, N. Ohno, S. Takamura

Workshop on the Electric Fields, Structures and Relaxation in Edge Plasmas; Satellite meeting of the 30th EPS Conference on Controlled Fusion and Plasma Physics

Structural Dynamics of Deep Negative Potential Well Formation in Small Tokamak Device CSTN-IV International conference

H. Kojima, Y. Fukuzawa, T. Manabe, N. Ohno, S. Takamura

30th EPS Conference on Controlled Fusion and Plasma Physics

高熱流トロイダルダイバータプラズマ模擬試験装置の製作

空重希，小島寛樹，上杉喜彦，大野哲靖，高村秀一

平成15年電気学会全国大会

プラズマ加熱LaB₆陰極を用いた径方向電界誘起とD-D核融合反応中性子源への応用

福澤祐馬，真鍋俊治，小島寛樹，大野哲靖，高村秀一，井口哲夫

平成15年電気学会全国大会

水素リサイクリングに対する回転ヘリカル磁場の効果 —周波数依存性—

小島寛樹，高村秀一

平成15年電気学会全国大会

Thermoelectron Emission from a Small Electrode heated with Plasma Heat Flux in AC Tokamak Discharge

T. Manabe, H. Kojima, Y. Fukuzawa, N. Ohno, S. Takamura

2002.11.26

Dynamic Effects of Rotating Helical Magnetic Field on Tokamak Edge International coauthorship International conference

S. Takamura, Y. Kikuchi, H. Kojima, Y. Uesugi, M. Toyoda, Y. Shiota, M. Kobayashi, V. P. Budaev

19th IAEA Fusion Energy Conference

プラズマ熱流による熱電子放出ターゲットの到達温度評価

真鍋俊治，小島寛樹，今里香恵，福澤祐馬，大野哲靖，高村秀一

平成14年度電気関係学会東海支部連合大会

プラズマ熱流によるタングステンとLaB₆の加熱とそのバイアス依存性

福澤祐馬，真鍋俊治，小島寛樹，今里香恵，大野哲靖，高村秀一

平成14年度電気関係学会東海支部連合大会

トカマクプラズマ自己加熱による六硼化ランタンの到達温度測定

今里香恵，小島寛樹，真鍋俊治，福澤祐馬，大野哲靖，高村秀一

第41回プラズマ若手夏の学校

長時間放電時における水素リサイクリング不均一性に対する回転ヘリカル磁場の効果

小島寛樹，高村秀一

第4回核融合エネルギー連合講演会

小型トカマク装置における熱電子放出バイアスを用いた径方向電場の形成とその中性子源への応用

真鍋俊治，小島寛樹，大野哲靖，高村秀一

第4回核融合エネルギー連合講演会

Effects of Rotating Helical Magnetic Field on Inhomogeneous Hydrogen Recycling in a Long Time Tokamak Discharge International conference

H. Kojima, S. Takamura

15th International Conference on Plasma Surface Interactions in Controlled Fusion Devices

Effects of Dynamic Ergodic Divertor on Inhomogeneities of Hydrogen Recycling in Long Time Tokamak Discharge International conference

H. Kojima, S. Takamura

1st International Workshop on Innovative Concepts for Plasma-Interactive Components in Fusion Devices

プラズマ自己加熱による熱電子放出を用いたプラズマ中への電界の印加

真鍋俊治，小島寛樹，大野哲靖，高村秀一

平成14年電気学会全国大会

長時間トカマク放電における水素リサイクリングの不均一性に対する回転ヘリカル磁場の効果

小島寛樹，高村秀一

日本物理学会第57回年次大会

長時間トカマク放電における水素リサイクリングの不均一性に対する回転ヘリカル磁場の効果

小島寛樹，高村秀一

平成13年度第2回PSI合同研究会

Effects of Rotating Helical Magnetic Field on Inhomogeneities of Hydrogen Recycling

H. Kojima, S. Takamura

Joint Conference of The 12th International Toki Conference on Plasma Physics and Controlled Nuclear Fusion and The 3rd General Scientific Assembly of Asia Plasma Fusion Association

Change of Hydrogen Recycling Property with Rotating Helical Magnetic Field in Long Time Discharge

H. Kojima, S. Takamura

2001.11.27

Investigation on Rotating Helical Field Penetration into Tokamak Plasmas International coauthorship

Y. Kikuchi, H. Kojima, M. Toyoda, V. P. Budaev, Y. Uesugi, S. Takamura

2001.11.28

長時間放電における回転ヘリカル磁場による水素リサイクリング特性の変化

小島寛樹，高村秀一

平成13年度第1回PSI研究会

Effects of Rotating Helical Magnetic Field on Hydrogen Recycling in Long Time Tokamak Discharge International conference

H. Kojima, S. Takamura

25th International Conference on Phenomena in Ionized Gases

Toroidal Dependence of Hydrogen Recycling Property with Helical Magnetic Perturbation in Long Time Discharge International conference

H. Kojima, S. Takamura

28th EPS Conference on Controlled Fusion and Plasma Physics

Effects of Dynamic Island Formations on Rotating Helical Magnetic Field Penetration into the Tokamak Plasma International conference

Y. Kikuchi, H. Kojima, T. Taniyama, M. Toyoda, Y. Uesugi, S. Takamura

28th EPS Conference on Controlled Fusion and Plasma Physics

長時間トカマク放電における水素リサイクリングに対する回転ヘリカル磁場の効果(III)

小島寛樹，高村秀一

平成13年電気学会全国大会

トカマクプラズマ中への回転ヘリカル摂動磁場の浸透に関する基礎研究

菊池祐介，小島寛樹，谷山智則，豊田光洋，上杉喜彦，高村秀一

平成13年電気学会全国大会

長時間トカマク放電における水素リサイクリングに対する回転ヘリカル磁場の効果

小島寛樹，高村秀一

第4回若手科学者によるプラズマ研究会

Study on Dynamic Ergodic Divertor in a Small Tokamak Device HYBTOK-II

Y. Kikuchi, H. Kojima, T. Taniyama, M. Toyoda, Y. Uesugi, S. Takamura

2000.11.27

回転ヘリカル磁場とトカマク磁場とのアルフヴェン共鳴

小島寛樹，真鍋俊治，有沢誠司，小林政弘，高村秀一

平成12年度電気関係学会東海支部連合大会

Effects of Rotating Helical Magnetic Field on Hydrogen Recycling in Long Time Tokamak Discharge

H. Kojima, S. Takamura

2000.9.8

Characteristics of Local Helical Coil System for Generating a Rotating Helical Field

Y. Kikuchi, H. Kojima, T. Taniyama, M. Toyoda, Y. Uesugi, S. Takamura

2000.9.8

Penetration Process of the Externally Applied Rotating Helical Field into the Tokamak Plasma International conference

M. Kobayashi, H. Kojima, S. Takamura

27th EPS Conference on Controlled Fusion and Plasma Physics

長時間トカマク放電における水素リサイクリングに対する回転ヘリカル磁場の効果

小島寛樹，小林政弘，高村秀一

平成12年電気学会全国大会

小型トカマク装置HYBTOK-IIにおける動的エルゴディックダイバータの初期実験

菊池祐介，小林政弘，小島寛樹，谷山智則，豊田光洋，上杉喜彦，高村秀一

平成12年電気学会全国大会

Improvement of Local Helical Coil Configuration for Dynamic Ergodic Divertor

Y. Kikuchi, K. Tashiro, M. Kobayashi, H. Kojima, K. Zhai, S. Takamura

10th International Toki Conference on Plasma Physics and Controlled Nuclear Fusion

長時間運転における水素リサイクリングに対する動的エルゴディックダイバータの効果

小島寛樹，小林政弘，高村秀一

プラズマ・核融合学会第16回年会

Modification of Externally Applied Rotating Helical Field due to the Island Formation in the Rotating Tokamak Plasma International conference

M. Kobayashi, T. Tuda, K. Tashiro, H. Kojima, Z. Kan, S. Takamura

2nd IAEA Technical Committee Meeting on Steady-State Operation of Magnetic Fusion Devices

Mode Structure of Stochastic Magnetic Field at the Tokamak Edge with Dynamic Ergodic Divertor International conference

S. Takamura, K. Tashiro, M. Kobayashi, H. Kojima, Z. Kan

7th International Workshop on Plasma Edge Theory in Fusion Devices

Experimental Investigation on Penetration of Rotating Magnetic Perturbations into the Tokamak Plasma International conference

M. Kobayashi, T. Tuda, Z. Kan, H. Kojima, K. Tashiro, S. Takamura

26th EPS Conference on Controlled Fusion and Plasma Physics

動的エルゴディックダイバータを有するトカマクプラズマの内部構造

小島寛樹，小林政弘，田代健二，Zhai Kan，高村秀一

平成11年電気学会全国大会

回転摂動磁場印加時におけるトカマクプラズマ内部構造の変化

小島寛樹，小林政弘，田代健二，Zhai Kan，高村秀一

電気学会東海支部プラズマエレクトロニクス若手セミナー

動的エルゴディックダイバータの内部磁場の解明

田代健二，小林政弘，小島寛樹，Zhai Kan，高村秀一

プラズマ・核融合学会第15回年会

回転摂動磁場印加時のトカマクプラズマ内部構造の変化

小島寛樹，小林政弘，田代健二，Zhai Kan，高村秀一

平成10年度電気関係学会東海支部連合大会

High-duty Long-duration Repetitive Tokamak Discharge with Static or Rotating Helical Magnetic Field at the Edge International conference

S. Takamura, M. Kobayashi, K. Tashiro, H. Kojima, K. Zhai, N. Ohno, M. Y. Ye, Y. Uesugi, M. Takagi

1998 International Congress on Plasma Physics combined with 25th EPS Conference on Controlled Fusion and Plasma Physics

Investigation of Hydrogen Plasma Detachment in the Divertor Plasma Simulator NAGDIS-II International coauthorship International conference

N. Ezumi, D. Nishijima, H. Kojima, N. Ohno, S. Takamura, S. I. Krasheninnikov, A. Yu. Pigarov

1998 International Congress on Plasma Physics combined with 25th EPS Conference on Controlled Fusion and Plasma Physics

Change in Detached Helium Plasma's Structure Associated with Molecular Activated Recombination International conference

D. Nishijima, N. Ezumi, H. Kojima, N. Ohno, S. Takamura

1998 International Congress on Plasma Physics combined with 25th EPS Conference on Controlled Fusion and Plasma Physics

Two-dimensional Structure of the Detached Recombining Helium Plasma Associated with Molecular Activated Recombination International coauthorship International conference

D. Nishijima, N. Ezumi, H. Kojima, N. Ohno, S. Takamura, S. I. Krasheninnikov, A. Yu. Pigarov

13th International Conference on Plasma Surface Interactions in Controlled Fusion Devices

Contribution of Molecular Activated Recombination to Hydrogen Plasma Detachment in the Divertor Plasma Simulator NAGDIS-II International coauthorship International conference

N. Ezumi, D. Nishijima, H. Kojima, N. Ohno, S. Takamura, S. I. Krasheninnikov, A. Yu. Pigarov

13th International Conference on Plasma Surface Interactions in Controlled Fusion Devices

窒素ガス入射による非接触再結合プラズマの構造変化

小島寛樹，江角直道，青木宏治，西島大輔，大野哲靖，高村秀一

平成10年電気学会全国大会

直線型ダイバータプラズマ模擬実験装置による非接触プラズマの基礎的な研究

江角直道，西島大輔，青木宏治，小島寛樹，大野哲靖，高村秀一

第1回若手科学者によるプラズマ研究会

窒素ガス入射による非接触再結合プラズマの構造変化

小島寛樹，西島大輔，青木宏治，江角直道，大野哲靖，高村秀一

平成9年度核融合科学研究所共同研究会定常化を目指したプラズマの分光計測

中性粒子の挙動が非接触プラズマの発生と構造に与える影響

青木宏治，江角直道，西島大輔，小島寛樹，大野哲靖，高木誠，高村秀一

プラズマ・核融合学会第14回年会

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<KOJIMA Hiroki>

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