Papers - HAYAKAWA, Naoki
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Improvement of AC Conditioning Effect in Vacuum by High Frequency Voltage Reviewed
R.Konagi, H.Kojima, S.Iitsuka, M.Kobayashi, N.Hayakawa
IEEJ Transactions on Electrical and Electronic Engineering Vol. 19 ( 11 ) page： 1781 - 1787 2024
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Enhancing Electrical Insulation Performance of Insulating Spacers using Functionally Graded Materials in Natural-Origin Gas GIS Reviewed
K.Okamoto, N.Hayakawa, K.Kato, N.Osawa, M.Kozako, H.Okubo
CIGRE Paris Session Vol. 11054 2024
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Effective High Frequency AC Conditioning in Vacuum Reviewed
R.Konagi, H.Kojima, S.Iitsuka, M.Kobayashi, N.Hayakawa
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 2024
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Partial Discharge Progress and Breakdown Characteristics of Oil-impregnated Paper Insulation System for Capacitor Voltage Transformers Reviewed
Y.Nagaki, R.Hayashi, H.Kojima, M.Yoshida, N.Hayakawa
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 2024
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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 Reviewed
永木雄也，林恭平，小島寛樹，吉田昌展，大谷彰，早川直樹
電気学会論文誌B 2023
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Breakdown Charge Dependence of Counter Electrode Material Adhesion and Dielectric Strength after Spark Conditioning in Vacuum Reviewed
N.Kita, H.Kojima, N.Hayakawa, H.Fukuda, K.Yamamura
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 2023
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Volume Effect of Dynamic Breakdown Strength in Liquid Nitrogen under Transient Bubble Disturbance for Resistive Superconducting Fault Current Limiters Reviewed
N.Hayakawa, Y.Mori, H.Kojima
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 29 ( 1 ) page： 264 - 269 2022
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Development of Sophisticated Cone-Type Insulating Spacer for 245 kV Class GIS by Functional Insulating Materials Reviewed
K.Okamoto, N.Hayakawa, M.Hikita, H.Okubo, K.Kato, N.Osawa
CIGRE Paris Session Vol. 10648 2022
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Electric Field Grading and Discharge Inception Voltage Improvement on HVDC GIS/GIL Spacer with Permittivity and Conductivity Graded Materials (ε/σ-FGM) Reviewed
Rachmawati, H.Kojima, K.Kato, N.Zebouchi, N.Hayakawa
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 29 ( 5 ) page： 1811 - 1817 2022
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Melting and Generation of Micro-protrusions on Cathode Surface during Spark Conditioning Process in Vacuum Reviewed
N.Kita, F.Kondo, H.Kojima, N.Hayakawa, H.Fukuda, K.Yamamura
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 29 ( 3 ) page： 1160 - 1166 2022
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Breakdown Characteristics of Cone-type ε-FGM Spacer for Gas Insulated Switchgears Reviewed
Y.Miyazaki, H.Kojima, H.Masui, H.Mitsudome, H.Yanase, K.Okamoto, K.Watanabe, K.Kato, N.Hayakawa
Vol. 141 ( 10 ) 2021.10
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Development of Insulation System to Prevent Local Carbonization inside Stator Core of a Product Inverter-fed Motor Reviewed
Vol. 141 ( 4 ) page： 260-268 2021.4
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DC Electric Field Distribution under Gas-Conductivity-Dominant Condition in Gas-Solid Composite Insulation Systems Reviewed
Vol. 141 ( 2 ) page： 156-163 2021.2
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Dielectric characteristics of liquid nitrogen / synthetic paper composite insulation system for extra high voltage HTS cable Reviewed
N.Hayakawa, K.Yamakami, T.Masuda, H.Kojima
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Vol. 31 ( 5 ) 2021
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Time and Space Transition of DC Electric Field Distribution Based on Emerging Field by Accumulated Charge in Gas-solid Composite Insulation Structure Reviewed
R.Nakane, N.Hayakawa, H.Okubo
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 2021
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Time Transition of Activated Conductivity Distribution in Air and Charge Accumulation in Air-solid Composite Insulation Systems under DC Partial Discharge Reviewed
R.Nakane, H.Kojima, N.Hayakawa
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 2021
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Electric Field Simulation of Permittivity and Conductivity Graded Materials (e/s-FGM) for HVDC GIS Spacers Reviewed International coauthorship
Rachmawati, H.Kojima, N.Hayakawa, K.Kato, N.Zebouchi
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 2021
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Alternative Test Method of Internal Arcing for Replacing SF6 by Air in SF6 Insulated Power Equipment Reviewed
M.Kotari, M.Iwata, H.Kojima, N.Hayakawa
Engineering Research Express Vol. 3 ( 035005 ) 2021
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Partial Discharge Inception Voltage under Inverter Surge Voltage Considering Interactive Effects of Environmental Factors Reviewed
Vol. 140 ( 7 ) page： 349-356 2020.7
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絶縁油-プレスボード複合絶縁構成における直流電界ストレスの時間・空間推移特性 Reviewed
中根龍一，加藤克巳， 早川直樹，大久保仁
電気学会論文誌A Vol. 140 ( 2 ) page： 56-63 2020.2
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インバータ駆動機におけるカーボン遊離現象の基礎検討 Reviewed
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
電気学会論文誌A Vol. 140 ( 1 ) page： 40-47 2020.1
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Quench-induced Dynamic Breakdown Characteristics of HTS Pancake Coil Model in Liquid Nitrogen for Resistive SFCL Invited Reviewed
N.Hayakawa, M.Mimbu, Y.Mori, H.Kojima, S.Isojima, M.Kuwata
Journal of Physics: Conference Series (JPCS) Vol. 1559 page： 12100 2020
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Fault Current Limitation Coordination of Multiple SFCLs in IEEE 14-Bus Test System Reviewed
N.Hayakawa, Y.Mori, H.Kojima
Journal of Physics: Conference Series (JPCS) Vol. 1559 page： 12138 2020
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Resin injection behavior in process of manufacturing insulation spacer with permittivity gradient using computational fluid dynamics
Imai Takahiro, Hoshina Yoshikazu, Kojima Hiroki, Hayakawa Naoki
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 26 ( 5 ) page： 1669-1677 2019.10
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Comparison of permittivity gradient in resin injected and simulated cone-shaped spacers
Imai Takahiro, Takeuchi Miwa, Hoshina Yoshikazu, Kojima Hiroki, Hayakawa Naoki
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 26 ( 5 ) page： 1678-1685 2019.10
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Dynamic Breakdown Characteristics of a Pancake Coil Model for Resistive-Type Superconducting Fault Current Limiters
Hayakawa Naoki, Mimbu Masataka, Kojimao Hiroki, Isojima Shigeki, Kuwata Minoru
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Vol. 29 ( 5 ) 2019.8
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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 Reviewed
梶武文，浅井洋光，小島寛樹，早川直樹
電気学会論文誌A Vol. 139 ( 1 ) page： 30-37 2019.1
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Simulation on Discharge Inception Voltage Improvement of GIS Spacer with Permittivity Graded Materials (epsilon-FGM) Using Flexible Mixture Casting Method
Hayakawa Naoki, Miyaji Yoshitaka, Kojima Hiroki, Kato Katsumi
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 25 ( 4 ) page： 1318-1323 2018.8
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Fault Current Limitation Coordination in Electric Power Grid With Superconducting Fault Current Limiters
Hayakawa Naoki, Maeno Yuya, Kojima Hiroki
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Vol. 28 ( 4 ) 2018.6
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Volume Effect of Dynamic Breakdown Strength in LN2 for Insulation Design of Resistive Superconducting Fault Current Limiters
Hayakawa Naoki, Ishida Kazuki, Mimbu Masataka, Kojima Hiroki, Isojima Shigeki, Kuwata Minoru
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Vol. 28 ( 4 ) 2018.6
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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 Reviewed
宮路仁崇，小島寛樹， 加藤克巳，早川直樹
電気学会論文誌A Vol. 138 ( 4 ) page： 155-162 2018
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Discharge Pattern Discrimination in Vacuum Interrupter with Non-contact Measurement of Shield Potential
Kong Fei, Kojima Hiroki, Hayakawa Naoki, Kimura Toshinori, Tsukima Mitsuru
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 24 ( 5 ) page： 3265-3269 2017.10
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Optimum Breakdown Charge for Maximum Dielectric Strength in Spark Conditioning in Vacuum under a Non-uniform Electric Field
Kojima H., Takahashi T., Hayakawa N., Hasegawa K., Sakaki M.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 24 ( 4 ) page： 2660-2665 2017.8
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Electrical Insulation Characteristics and Mechanisms of Low Dielectric Loss Materials for High-Voltage HTS Cables
Hayakawa Naoki, Ishida Kazuki, Matsuoka Tatsuya, Kojima Hiroki
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Vol. 27 ( 4 ) 2017.6
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Breakdown Characteristics and Mechanisms of Liquid Nitrogen Under Transient Thermal Stress for Superconducting Fault Current Limiters
Hayakawa Naoki, Matsuoka Tatsuya, Kojima Hiroki, Isojima Shigeki, Kuwata Minoru
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Vol. 27 ( 4 ) 2017.6
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Calculation Model for Predicting Partial-discharge Inception Voltage in a Non-uniform Air Gap while Considering the Effect of Humidity
Rokunohe Toshiaki, Kato Tatsuro, Kojima Hiroki, Hayakawa Naoki, Okubo Hitoshi
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION Vol. 24 ( 2 ) page： 1123-1130 2017.4
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ナノ粒子添加絶縁油の交流電気絶縁破壊電圧の向上メカニズム Reviewed
小島寛樹，近藤貴文，花井正広，早川直樹
電気学会論文誌A Vol. 137 ( 2 ) page： 101-106 2017
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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 Reviewed
脇本亨，小島寛樹，早川直樹
電気学会論文誌A Vol. 136 ( 3 ) page： 121-127 2016
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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 Reviewed
中野裕介，小島寛樹，土屋賢治，早川直樹
電気学会論文誌A Vol. 136 ( 3 ) page： 128-134 2016
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Pressure Dependence and Size Effect of LN2 Breakdown Characteristics under Transient Thermal Stress Reviewed
N.Hayakawa, T.Matsuoka, K.Ishida, H.Kojima, S.Isojima, M.Kuwata
IEEE Trans. on Applied Superconductivity Vol. 26 ( 3 ) page： 7700604 2016
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Discharge Characteristics of Composite Insulation System with Floating Electrode and Solid Insulator in Vacuum Reviewed
F.Kong, Y.Nakano, H.Kojima, N.Hayakawa, T.Kimura, M.Tsukima
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 23 ( 2 ) page： 1219-1225 2016
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Discharge Characteristics for Various Discharge Patterns under Negative Lightning Impulse Voltage in Vacuum Reviewed
F.Kong, Y.Nakano, H.Kojima, N.Hayakawa, T.Kimura, M.Tsukima
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 23 ( 2 ) page： 813-818 2016
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Fabrication and Simulation of Permittivity Graded Materials for Electric Field Grading of Gas Insulated Power Apparatus Reviewed
N.Hayakawa, J.Ishiguro, H.Kojima, K.Kato, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 23 ( 1 ) page： 547-554 2016
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Classification of Impulse Breakdown Mechanisms under Non-uniform Electric Field in Air Reviewed
H.Kojima, K.Hotta, T.Kitamura, N.Hayakawa, A.Otake, K.Kobayashi, T.Kato, T.Rokunohe H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 23 ( 1 ) page： 194-201 2016
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Analysis of Conditioning and Damaging Process in Vacuum Based on Breakdown Probability Distribution Reviewed
H.Kojima, Y.Otake, T.Takahashi, N.Hayakawa, K.Hasegawa, H.Saito, M.Sakaki
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 23 ( 1 ) page： 43-48 2016
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Control and Suppression of Impulse Surface Flashover in Vacuum Based on Discharge Development Mechanisms Reviewed
Y.Nakano, H.Kojima, K.Tsuchiya, N.Hayakawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 23 ( 1 ) page： 35-42 2016
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Dependence of Spark Conditioning on Breakdown Charge and Electrode Material under a Non-Uniform Electric Field Reviewed
H.Kojima, T.Takahashi, N.Hayakawa, K.Hasegawa, H.Saito, M.Sakaki
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 23 ( 5 ) page： 3224-3230 2016
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真空中の複合絶縁系における放電パターンの識別 Reviewed
孔飛，小島寛樹，木村俊則，月間満，早川直樹
電気学会論文誌A Vol. 136 ( 9 ) page： 594-602 2016
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Measurement and Evaluation of Partial Discharge Inception Voltage for Enameled Rectangular Wires under AC Voltage Reviewed
T.Wakimoto, H.Kojima, N.Hayakawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 23 ( 6 ) page： 3566-3574 2016
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Experimental Results of 275 kV-3 kA REBCO HTS Power Cable Reviewed
M.Yagi, J.Liu, S.Mukoyama, T.Mitsuhashi, J.Teng, N.Hayakawa, X.Wang, A.Ishiyama,
IEEE Trans. on Applied Superconductivity Vol. 25 ( 3 ) page： 5401405 2015
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Fault Current Limitation Coordination in Power Transmission System with Superconducting Fault Current Limiting Cables (SFCLC) Reviewed
H.Kojima, T.Osawa, N.Hayakawa
IEEE Trans. on Applied Superconductivity Vol. 25 ( 3 ) page： 5401904 2015
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Quench-Induced Dynamic Breakdown Characteristics of LN2 and LN2/PPLP Composite Electrical Insulation System for Superconducting Power Apparatus Reviewed
N.Hayakawa, T.Matsuoka, S.Nishimachi, H.Kojima
IEEE Trans. on Applied Superconductivity Vol. 25 ( 3 ) page： 7700304 2015
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Power Flow Control and Maintenance Strategy of Transformers in Transmission and Distribution Systems Reviewed
H.Kojima, K.Fukaya, N.Hayakawa, M.Hanai, H.Okubo
Vol. 135 ( 5 ) page： 316-321 2015
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Impulse Surface Flashover Development Associated with Transient Charging by Explosive Electron Emission in Vacuum Reviewed
Y.Nakano, H.Kojima, K.Tsuchiya, N.Hayakawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 22 ( 4 ) page： 2390-2397 2015
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Size Effect on Breakdown Strength in Sub-cooled Liquid Nitrogen for Superconducting Power Apparatus Reviewed
N.Hayakawa, S.Nishimachi, H.Kojima, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 22 ( 5 ) page： 2565-2571 2015
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Influence of longitudinal temperature distribution on current limiting function of Superconducting Fault Current Limiting Cable (SFCLC) Reviewed
H.Kojima, T.Osawa, N.Hayakawa , M.Hanai, H.Okubo
Journal of Physics: Conference Series (JPCS) Vol. 507 page： 032026 2014
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A Novel Electrical Insulating Material for 275 kV High-Voltage HTS Cable with Low Dielectric Loss Reviewed
N.Hayakawa, S.Nishimachi, O.Maruyama, T.Ohkuma, J.Liu, M.Yagi
Journal of Physics: Conference Series (JPCS) Vol. 507 page： 032021 2014
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Pre-discharge and Flashover Characteristics of Impulse Surface Discharge in Vacuum Reviewed
Y.Nakano, H.Kojima, N.Hayakawa, K.Tsuchiya, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 21 ( 1 ) page： 403-410 2014
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Technique for Discriminating the Type of PD in SF6 Gas Using the UHF Method and the PD Current with a Metallic Particle Reviewed
M.Hanai, H.Kojima, N.Hayakawa, R.Mizuno, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 21 ( 1 ) page： 88-95 2014
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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進展過程の過渡帯電特性 Reviewed
中野裕介，小島寛樹，土屋賢治，早川直樹
電気学会論文誌A Vol. 134 ( 11 ) page： 578-584 2014
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Physical Mechanisms of Partial Discharges at Nitrogen Filled Delamination in Epoxy Cast Resin Power Apparatus Reviewed
D.-E.A.Mansour, H.Kojima, N.Hayakawa, M.Hanai, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 20 ( 2 ) page： 454-461 2013
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Status of 275 kV Class REBCO Superconducting Cable Development Reviewed
S.Mukoyama, M.Yagi, T.Mitsuhashi, T.Nomura, J.Ten, R.Nakayama, T.Ohkuma, O.Maruyama, Y.Aoki, T.Saitoh, N.Amemiya, A.Ishiyama, N.Hayakawa
IEEE Trans. on Applied Superconductivity Vol. 23 ( 3 ) page： 5402804 2013
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Feasibility Study on Superconducting Power Flow Controller and Fault Current Limiter (SPFCL) Reviewed
N.Hayakawa, X.Mao, H.Kojima, M.Hanai, H.Okubo, N.Kashima, S.Nagaya, S.Sugimoto
IEEE Trans. on Applied Superconductivity Vol. 23 ( 3 ) page： 5600504 2013
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Development of 66 kV and 275 kV Class REBCO HTS Power Cables Reviewed
O.Maruyama, T.Ohkuma, T.Masuda, Y.Ashibe, S.Mukoyama, M.Yagi, T.Saitoh, T.Hasegawa, N.Amemiya, A.Ishiyama, N.Hayakawa
IEEE Trans. on Applied Superconductivity Vol. 23 ( 3 ) page： 5401405 2013
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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 Reviewed
小島寛樹，鈴木隆文，早川直樹，花井正広，大久保仁
電気学会論文誌B Vol. 133 ( 1 ) page： 114-120 2013
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Integration of Asset Management and Smart Grid with Intelligent Grid Management System Reviewed
M.Hanai, H.Kojima, N.Hayakawa, K.Shinoda, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 20 ( 6 ) page： 2195-2202 2013
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Charge behavior in Palm Fatty Acid Ester Oil (PFAE) / pressboard composite insulation system under voltage application Reviewed
H.Kojima. N.Hayakawa, H.Okubo, K.Kato, K.Kawanishi, H.Koide
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 19 ( 2 ) page： 419-423 2012
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Estimation of Partial Discharge Inception Voltage of Magnet Wire under Inverter Surge Voltage by Volume-Time Theory Reviewed
N.Hayakawa, F.Shimizu, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 19 ( 2 ) page： 550-557 2012
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Feasibility Study on High Temperature Superconducting Fault Current Limiting Cable (SFCLC) Using Flux Flow Resistance Reviewed
H.Kojima, F.Kato, M.Hanai, N.Hayakawa, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 22 ( 2 ) page： 4800105 2012
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Current limitation and recovery function for superconducting fault current limiting transformer (SFCLT) Reviewed
J.Himbele, H.Kojima, N.Hayakawa, M.Hanai, H.Okubo
Physics Procedeia Vol. 36 page： 841-844 2012
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Superconducting Fault Current Limiting Cable (SFCLC) with Current Limiting and Recovery Function Reviewed
H.Kojima, F.Kato, N.Hayakawa, M.Hanai, H.Okubo
Physics Procedeia Vol. 36 page： 1296-1300 2012
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Recent Progress in Electrical Insulation Techniques for HTS Power Apparatus Reviewed
N.Hayakawa, H.Kojima, M.Hanai, H.Okubo
Physics Procedeia Vol. 36 page： 1305-1308 2012
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周波数応答解析によるモータサージ電圧の推定と抑制 Reviewed
脇本亨，高橋芳光，木村統公，鳴海礼斗史，早川直樹
電気学会論文誌A Vol. 132 ( 8 ) page： 630-637 2012
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Model Cable Tests for a 275 kV 3 kA HTS Power Cable Reviewed
S.Mukoyama, M.Yagi, T.Yonemura, T.Nomura, N.Fujiwara, Y.Ichikawa, Y.Aoki, T.Saitoh, N.Amemiya, A.Ishiyama, N.Hayakawa
IEEE Trans. on Applied Superconductivity Vol. 21 ( 3 ) page： 976-979 2011
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Analysis of Current Limiting and Recovery Characteristics of Superconducting Fault Current Limiting Transformer (SFCLT) with YBCO Coated Conductors Reviewed
N.Hayakawa, T.Kito, H.Kojima, M.Hanai, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 21 ( 3 ) page： 1422-1425 2011
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Development Process of Impulse Surface Flashover on Alumina Dielectrics in Vacuum Reviewed
H.Kojima, N.Hayakawa, T.Ishida, H.Okubo, K.Tsuchiya
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 18 ( 3 ) page： 918-923 2011
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Evaluation of UHF Method for Partial Discharge Measurement by Simultaneous Observation of UHF Signal and Current Pulse Waveforms Reviewed
M.Yoshida, H.Kojima, N.Hayakawa, F.Endo, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 18 ( 2 ) page： 425-431 2011
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Progress in Development of Superconducting Fault Current Limiting Transformer (SFCLT) Reviewed
N.Hayakawa, H.Kojima, M.Hanai, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 21 ( 3 ) page： 1397-1400 2011
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Current Limiting and Recovery Characteristics of 2 MVA Class Superconducting Fault Current Limiting Transformer (SFCLT) Reviewed
H.Kojima, M.Kotari, T.Kito, N.Hayakawa, M.Hanai, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 21 ( 3 ) page： 1401-1404 2011
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Conditioning Mechanism of Cu-Cr Electrode Based on Electrode Surface State under Impulse Voltage Application in Vacuum Reviewed
H.Kojima, N.Hayakawa, R.Nishimura, H.Okubo, H.Sato, H.Saito, Y.Noda
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 18 ( 6 ) page： 2108-2114 2011
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部分放電の時系列測定によるGIS内部の欠陥状態識別 Reviewed
吉田昌展，鈴木啓介，小島寛樹，早川直樹，花井正広，大久保仁
電気学会論文誌B Vol. 131 ( 11 ) page： 905-911 2011
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湿度の影響を考慮した気中不平等ギャップにおける部分放電開始計算モデルの開発 Reviewed
柳田憲史，加藤達朗，六戸敏昭，岩田健，小島寛樹，早川直樹，大久保仁
電気学会論文誌A Vol. 131 ( 12 ) page： 1017-1023 2011
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Partial Discharge Activities under AC/Impulse Superimposed Voltage in LN2/Polypropylene Laminated Paper Insulation System for HTS Cables Reviewed
N.Hayakawa, R.Yamaguchi, U.Ukai, H.Kojima, F.Endo, H.Okubo
Journal of Physics: Conference Series (JPCS) Vol. 234 ( 032020 ) 2010
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Charge Accumulation Effects on Time Transition of Partial Discharge Activity at GIS Spacer Defects Reviewed
D.A.Mansour, K.Nishizawa, H.Kojima, N.Hayakawa, F.Endo, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 17 ( 1 ) page： 247-255 2010
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Dielectric Properties of Epoxy/Alumina Nanocomposite Influenced by Agglomerates Control Reviewed
M.Kurimoto, H.Okubo, K.Kato, M.Hanai, Y.Hoshina, M.Takei, N.Hayakawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 17 ( 3 ) page： 1268-1275 2010
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Partial Discharge and Associated Mechanisms for Micro Gap Delamination at Epoxy Spacer in GIS Reviewed
D.A.Mansour, K.Nishizawa, H.Kojima, N.Hayakawa, F.Endo, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 17 ( 3 ) page： 861-867 2010
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Permittivity Characteristics of Epoxy/Alumina Nanocomposite with High Particle Dispersibility by Combining Ultrasonic Wave and Centrifugal Force Reviewed
M.Kurimoto, H.Okubo, K.Kato, M.Hanai, Y.Hoshina, M.Takei, N.Hayakawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 17 ( 4 ) page： 1268-1275 2010
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Development of 2 MVA Class Superconducting Fault Current Limiting Transformer (SFCLT) with YBCO Coated Conductors Reviewed
M.Kotari, H.Kojima, N.Hayakawa, F.Endo, H.Okubo
Journal of Physics: Conference Series (JPCS) Vol. 234 ( 032070 ) page： - 2010
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Surface Charge Accumulation and Partial Discharge Activity for Small Gaps of Electrode/Epoxy Interface in SF6 Gas Reviewed
D.A.Mansour, H.Kojima, N.Hayakawa, F.Endo, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 16 ( 4 ) page： 1150-1157 2009
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Current Limiting Characteristics of Parallel-Connected YBCO Coated Conductors for High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) Reviewed
K.Omura, H.Kojima, N.Hayakawa, F.Endo, M.Noe, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 19 ( 3 ) page： 1880-1883 2009
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Dynamic Thermal Characteristics of HTS Coil for Conduction-cooled SMES Reviewed
H.Kojima, X.Chen, N.Hayakawa, F.Endo, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 19 ( 3 ) page： 2036-2039 2009
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*Time Variation of Partial Discharge Activity Leading to Breakdown of Magnet Wire under Repetitive Surge Voltage Application Reviewed
N.Hayakawa, H.Inano, Y.Nakamura, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 15 ( 6 ) page： 1701-1706 2008
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*Self-recovery Characteristics of High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductors Reviewed
H.Kojima, S.Ito, N.Hayakawa, F.Endo, M.Noe, H.Okubo
Journal of Physics: Conference Series page： 12154 2008
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*Quench-induced Partial Discharge Characteristics of HTS Cables Reviewed
N.Hayakawa, S.Ueyama, H.Kojima, F.Endo, Y.Ashibe, T.Masuda, M.Hirose
Journal of Physics: Conference Series page： 12053 2008
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*Partial Discharge Activity in Electrical Insulation for High Temperature Superconducting (HTS) Cables Reviewed
H.Okubo, H.Kojima, F.Endo, K.Sahara, R.Yamaguchi, N.Hayakawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 15 ( 3 ) page： 647-654 2008
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Technical Development on Partial Discharge Measurement and Electrical Insulation Techniques for Low Voltage Motors Driven by Voltage Inverters Reviewed
H.Okubo, N.Hayakawa, G.C.Montanari
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 14 ( 6 ) page： 1516-1530 2007
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Partial Discharge Inception and Propagation Characteristics of Magnet Wire for Inverter-Fed Motor under Surge Voltage Condition Reviewed
N.Hayakawa, M.Morikawa, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 14 ( 1 ) page： 39-45 2007
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Thermal Runaway Characteristics of Bi2212 Coil for Conduction-cooled SMES Reviewed
H.Kojima, N.Hayakawa, S.Noguchi, F.Endo, N.Hirano, S.Nagaya, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 17 ( 2 ) page： 1959-1962 2007
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High-Tc Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with 2G Coated Conductors Reviewed
H.Okubo, C.Kurupakorn, S.Ito, H.Kojima, N.Hayakawa, F.Endo, M.Noe
IEEE Trans. on Applied Superconductivity Vol. 17 ( 2 ) page： 1768-1771 2007
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Electrical Insulation Characteristics of HTS Cables under Quench-induced Thermal Stress Condition Reviewed
N.Hayakawa, S.Ueyama, H.Kojima, F.Endo, T.Masuda, M.Hirose
IEEE Trans. on Applied Superconductivity Vol. 17 ( 2 ) page： 1660-1663 2007
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*Breakdown Characteristics of N2O Gas Mixtures for Quasiuniform Electric Field under Lightning Impulse Voltage Reviewed
H.Kojima, O.Kinoshita, N.Hayakawa, F.Endo, H.Okubo, M.Yoshida, T.Ogawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 14 ( 6 ) page： 1492-1497 2007
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N2O混合ガスの絶縁特性におけるシナジズム効果 Reviewed
早川直樹，木下修，小島寛樹，遠藤奎将，吉田昌展，小川達也，大久保仁
電気学会論文誌B Vol. 126 ( 11 ) page： 1164-1170 2006
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Streamer and Leader Discharge Propagation Characteristics Leading to Breakdown in Electronegative Gases Reviewed
N.Hayakawa, K.Hatta, S.Okabe, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 113 ( 4 ) page： 842-849 2006
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Impulse and ac Partial Discharge Inception and Breakdown Characteristics of LN2/Polypropylene Laminated Paper Composite Insulation System Reviewed
H.Okubo, H.Kojima, F.Endo, K.Sahara, N.Hayakawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 113 ( 3 ) page： 664-669 2006
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Common Insulating Properties in Insulating Materials Reviewed
S.Okabe, N.Hayakawa, H.Murase, H.Hama, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 113 ( 2 ) page： 327-335 2006
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Simulation of Electrical and Thermal Behavior of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT) Reviewed
C.Kurupakorn, H.Kojima, N.Hayakawa, F.Endo, N.Kashima, S.Nagaya, M.Noe, H.Okubo
Journal of Physics: Conference Series Vol. 43 page： 950-953 2006
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Electrical and Thermal Characteristics of Bi2212/Ag HTS Coils for Conduction-cooled SMES Reviewed
N.Hayakawa, S.Noguchi, C.Kurupakorn, H.Kojima, F.Endo, N.Hirano, S.Nagaya, H.Okubo
Journal of Physics: Conference Series Vol. 43 page： 813-816 2006
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Impulse Partial Discharge Characteristics and Their Mechanisms under Non-uniform Electric Field in N2/SF6 Gas Mixtures Reviewed
N.Hayakawa, Y.Yoshitake, N.Koshino, T.Ueda, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 12 ( 5 ) page： 1035-1042 2005
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A Novel Technique for Partial Discharge and Breakdown Investigation Based on Current Pulse Waveform Analysis Reviewed
H.Okubo, N.Hayakawa
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 12 ( 4 ) page： 736-744 2005
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Temperature Dependence of Critical Current at 4.2K–55K of Conduction-cooled Bi2212/Ag Wires Reviewed
H.Kojima, S.Noguchi, C.Kurupakorn, N.Hayakawa, M.Goto, N.Hirano, S.Nagaya, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 15 ( 2 ) page： 2550-2553 2005
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High voltage requirements and test of a 10 MVA superconducting fault current limiter Reviewed
M.Noe, K.-P.Juengst, S.Elschner, J.Bock, F.Breuer, R.Kreutz, M.Kleimaier, K.-H.Weck, N. Hayakawa
IEEE Trans. on Applied Superconductivity Vol. 15 ( 2 ) page： 2082-2085 2005
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Recovery Characteristics after Current Limitation of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT) Reviewed
C.Kurupakorn, H.Kojima, N.Hayakawa, M.Goto, N.Kashima, S.Nagaya, M.Noe, K.-P.Juengst, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 15 ( 2 ) page： 1859-1862 2005
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Dielectric Characteristics of HTS Cables Based on Partial Discharge Measurement Reviewed
N.Hayakawa, M.Nagino, H.Kojima, M.Goto, T.Takahashi, K.Yasuda, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 15 ( 2 ) page： 1802-1805 2005
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CO2ガスのインパルス比と初期電子発生特性 Reviewed
越野尚人，木下修，早川直樹，五島久司，岡部成光，森井浩，大久保仁
電気学会論文誌B Vol. 125 ( 6 ) page： 568-574 2005
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Partial Discharge Inception Characteristics of LN2/PP Laminated Paper Composite Insulation System for High Temperature Superconducting Cable Reviewed
N.Hayakawa, T.Kobayashi, M.Hazeyama, T.Takahashi, K.Yasuda, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 12 ( 1 ) page： 166-174 2005
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Partial discharge characteristics of inverter-fed motor coil samples under ac and surge voltage conditions Reviewed
N.Hayakawa, H.Okubo
IEEE Electrical Insulation Magazine Vol. 21 ( 1 ) page： 5-10 2005
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Electrical Insulation Characteristics at Cryogenic Temperature for High Temperature Superconducting Cables Reviewed
H.Okubo, N.Hayakawa
KIEE International Transactions on Electrophysics and Applications Vol. 4-C ( 1 ) page： 15-20 2004
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高温超電導限流変圧器（HTc-SFCLT）の開発 Reviewed
クルパコン チャチャヴァン，早川直樹，鹿島直二，長屋重夫，大久保仁
電気学会論文誌B Vol. 124 ( 10 ) page： 1193-1199 2004
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Development of High Temperature Superconducting Fault Current Limiting Transformer (HTc-SFCLT) with Bi2212 Bulk Coil Reviewed
C.Kurupakorn, N.Hayakawa, H.Okubo, N.Kashima, S.Nagaya, M.Noe, K.-P.Juengst
IEEE Trans. on Applied Superconductivity Vol. 14 ( 2 ) page： 900-903 2004
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棒－平板電極における空気および窒素ガス中インパルス部分放電および絶縁破壊特性 Reviewed
斉藤 仁，森田啓一，吉川隆司，早川直樹，大久保仁
電気学会論文誌B Vol. 123 ( 2 ) page： 169-174 2003
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Electrical Insulation Performance under Thermal and Electric Combined Stress for Resistive Superconducting Fault Current Limiters Reviewed
N.Hayakawa, M.Noe, K.-P.Juengst, H.Okubo
IEEE Trans. on Applied Superconductivity Vol. 13 ( 2 ) page： 1996-1999 2003
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V-t characteristics for Partial Discharge Inception of High Temperature Superconducting Power Transmission Cables Reviewed
M.Hazeyama, N.Hayakawa, K.Matsuo, T.Masuda, H.Okubo
Physica C Vol. 372-376 ( 3 ) page： 1551-1554 2002
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Partial Discharge Inception Characteristics under Butt Gap Condition in Liquid Nitrogen/PPLP Composite Insulation System for High Temperature Superconducting Cable Reviewed
M.Hazeyama, T.Kobayashi, N.Hayakawa, S.Honjo, T.Masuda, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 9 ( 6 ) page： 939-944 2002
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V-t Characteristics of Partial Discharge Inception in Liquid Nitrogen/PPLP Composite Insulation System for HTS Superconducting Cable Reviewed
H.Okubo, M.Hazeyama, N.Hayakawa, S.Honjo, T.Masuda
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 9 ( 6 ) page： 945-951 2002
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Impulse Partial Discharge and Breakdown Characteristics of Rod-Plane Gaps in N2/SF6 Gas Mixtures Reviewed
H.Saitoh, K.Morita, T.Kikkawa, N.Hayakawa, H.Okubo
IEEE Trans. on Dielectrics and Electrical Insulation Vol. 9 ( 4 ) page： 544-550 2002
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Partial discharge and breakdown mechanisms in ultra-dilute SF6 and PFC gases mixed with N2 gas Reviewed
H.Okubo, T.Yamada, K.Hatta, N.Hayakawa, S.Yuasa, S.Okabe
Journal of Physics D: Applied Physics Vol. 35 ( 21 ) page： 2760-2765 2002
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Investigation of Electric Insulation Diagnosis of Solid Insulators in GIS by Partial Discharge Current Pulse Waveform Analysis (PD-CPWA) Reviewed
H.Okubo, A.Matsushita, S.Watanabe, N.Hayakawa, T.Kumai
IEEE PES T&D Vol. 2 page： 925-930 2002
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Development of Superconducting Fault Current Limiting Transformer (SFCLT) with the Functions of Fault Current Suppression and System Stability Improvement Reviewed
H.Okubo, H.Kagawa, N.Hayakawa, N.Kashima, S.Nagaya
IEEE PES T&D Vol. 1 page： 301-306 2002
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Experimental Study on Superconducting Fault Current Limiting Transformer (SFCLT) for Fault Current Suppression and System Stability Improvement Reviewed
H.Kagawa, N.Hayakawa, N.Kashima, S.Nagaya, H.Okubo
Physica C Vol. 372-376 ( 3 ) page： 1706-1710 2002