研究者詳細 - 小迫　雅裕

論文 - 小迫　雅裕

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Data analysis for Imploving Diagnostic Accuracy in Partial Discharge Monitoring Systems using Power Line Communication 査読有り国際誌

Ryota Kimoto, Lunnetta Safura Lumba, Akito Hodai, Masayuki Hikita, Masahiro Kozako

2025 Electrical Insulation Conference (EIC) 39 - 42 2025年06月

Investigation of Optimal Electrical Insulation Systems of Stator Windings for Inverter-Fed Motors 査読有り国際誌

T.Iwanaga, K.Zaizen, T.Okamoto, Y.Yamanaka, K.Miyazaki, T.Kuno, M.Hikita, M.Kozako

2025 Electrical Insulation Conference (EIC) 277 - 280 2025年06月

Experimental Investigation on Detection and Localization of AC Partial Discharge in Form Wound Stator Windings in Rotating Machines using HFCT Sensors 査読有り国際誌

T.Kajiyama, Y.Nagatani, K.Miyazaki, M.Hikita, T.Kuno, T.Iwanaga, M.Kozako, K.Zaizen, T.Yamada, Y.Inoue, T.Okamoto

2025 Electrical Insulation Conference (EIC) 188 - 191 2025年06月

Morphological effect on high-voltage insulation properties in polypropylene/elastomer binary blends: An experimental and simulation study 査読有り国際誌

Lee O.U., Kwon T., Normansah N.M.b., Kim D.K., Kwon Y.J., Kim M.J., Lee D.H., Kwon I.S., Eom Y., Kim H., Kozako M., Kim M., Yu S.

Polymer Degradation and Stability 234 2025年04月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Polypropylene (PP)/elastomer blends have been widely studied as promising insulation materials for high-voltage (HV) power cables. Among various factors, the size of elastomer domains critically influences their electrical insulation performance, such as resistivity and breakdown strength (BDS). However, this relationship remains poorly understood. This study investigates the effect of the polyolefin elastomer (POE) domain size on the high-voltage insulation properties of the PP/POE blend. The binary blends were prepared through melt-blending of the PP and POE at the different mixing temperature from 185 to 235 °C. As an increase of the mixing temperature, the size of dispersed POE domain was linearly increased due to the viscosity differences between the PP and POE. In addition, the tensile strength, elongation, volume resistivity, and DC breakdown strength were decreased with mixing temperature, which were thus correlated with the POE domain size. The BDS values derived from simulations were consistent with those calculated via the Power law equation, showing a decline in BDS with increasing mixing temperature. Analysis of electric field distribution and space charge accumulation indicated that smaller POE domains more effectively mitigate electric field imbalances, delaying BD compared to larger domains. This study highlights the significant role of morphology in determining the insulation performance of polymer blends, providing valuable insights for the design of HV insulation materials.

DOI： 10.1016/j.polymdegradstab.2025.111223

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Improving the high-voltage insulation properties of polypropylene by introducing trace addition of polyvinylidene fluoride: An experimental and simulation study 査読有り国際誌

Lee O., Kim D.K., Kim H., Lee S.H., Kwon T., Kwon I.S., Shinozaki K., Hikita M., Lee J.H., Lee D.H., Kim M.H., Kozako M., Yu S.

Composites Science and Technology 259 2025年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Various additives ranging from inorganic nanoparticles to organic additives have been suggested to improve the insulation performance of polymeric materials for high-voltage engineering applications. Herein, a simple method for doping fluorine into a polypropylene (PP) matrix was presented by melt-blending of isotactic PP (iPP) with a small amount of polyvinylidene fluoride (PVDF) as a thermoplastic voltage stabilizer (TVS). During melt-mixing, the PVDF TVS, which is immiscible with PP, is gradually split into smaller domains within the iPP matrix and finely distributed, especially at a low PVDF content. The direct current (DC) breakdown strength (BDS) values of the PVDF-doped iPP increased by 110 % and 149 % at 25 and 110 °C, respectively, compared to those of the pristine PP, while its dielectric permittivity and loss tangent values remained nearly similar to those of iPP at wide temperature between 25 and 140 °C and frequency range between 1 Hz and 10 MHz. Quantum chemical simulation results reveal that a small amount of PVDF with high dipole moment introduces deep trap sites within the polymer matrix, which contribute for increasing BDS of iPP. Also, the PP with a small amount of PVDF dopants below 1.0 phr exhibited no any decrease in the tensile strength and elongation at break values. Therefore, the PVDF-doped iPP is anticipated as a potential candidate as high-performance high-voltage insulation materials for next-generation insulation applications.

DOI： 10.1016/j.compscitech.2024.110939

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Acoustic Partial Discharge Localization in Refined, Bleached and Deodorized Palm Oil (RBDPO) Based on the Savitzky-Golay and Moving Average Denoising Methods 査読有り

Ahmad N.D., Azis N., Jasni J., Rezali K.A.M., Talib M.A., Ali N.H.N., Kozako M.

Pertanika Journal of Science and Technology 33 ( Special Issue 4 ) 115 - 128 2025年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

This research describes an investigation on the localization of partial discharge (PD) in Refined, Bleached and Deodorized Palm Oil (RBDPO) with the applications of 2 denoising methods, namely Savitzky-Golay (SG) and Moving Average (MA). A needle-plane electrode setup was used to initiate the PD. The electrical PD signal measurement was carried out through the impedance matching circuit (IMC), and the acoustic PD signal was obtained by acoustic emission (AE) sensors. The AE sensors were attached to the tank’s surface, and pre-amplifiers were used to boost the acquired acoustic PD signal. A high-voltage AC supply initiated the PD within the test tank filled with RBDPO. Both electrical and acoustic PD signals were denoised by SG and MA methods. The 2 denoising methods were evaluated based on the signal-to-noise ratio (SNR), root mean squared error (RMSE) and correlation coefficient (CC) metrics. The denoised acoustic PD signals were then utilized in the time difference of arrival (TDOA) technique to perform PD localization. The SG was found to be more effective than the MA in denoising both the electrical and acoustic PD signals based on its low RMSE and high CC. The estimated PD source locations based on the SG-denoised acoustic PD signals are closer to the actual PD source than those derived from the MA-denoised signals.

DOI： 10.47836/pjst.33.S4.07

Scopus

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Effect of Electrical Field on Conductivity of Synthetic Ester Induced by Space Charge Accumulation 査読有り国際誌

Yu R., Matharage S., Shen S., Wang Z., Tsuchie M., Kozako M., Hikita M.

IEEE Transactions on Dielectrics and Electrical Insulation 32 ( 3 ) 1279 - 1288 2025年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Synthetic ester has emerged as an alternative in applications where mineral oil has traditionally been used. Furthermore, their new applications in areas such as converter transformers and battery energy storage systems are currently being investigated. Conductivity of insulating materials is a crucial parameter for such new applications. This article investigates the impact of electrical field on the conductivity of synthetic ester through a combination of experimental and simulation studies. The experimental results indicate that short-term conductivity increases while long-term conductivity exhibits a nonlinear trend with applied electrical field. The simulation results show that the increase in the measured short-term conductivity is due to field-enhanced charge dissociation while the nonlinear trend in the measured long-term conductivity is a combined effect of space charge accumulation and field distortion. Furthermore, the simulation model incorporating space charge accumulation and charge injection is used to explain electrical field dependent conductivity phenomena, and key parameters and formulae describing field enhanced intrinsic and injected charge density are identified for synthetic ester and compared with those of mineral oil.

DOI： 10.1109/TDEI.2025.3527414

Scopus

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Investigation of Liquid Insulating Material for Power Module Encapsulation: Effects on Partial Discharge and Electric Field Characteristics 査読有り国際誌

Tomaiwa R., Suenaga S., Okamoto T., Tsuchie M., Hikita M., Kozako M.

Proceedings IEEE International Conference on Dielectric Liquids 2025年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Next-generation power modules require rigorous evaluation of insulating substrates due to increasing voltage levels and the associated risk of partial discharge (PD). PD typically occurs in regions of high electric field intensity, particularly at encapsulant–metal interfaces, and leads to dielectric degradation. Conventional encapsulants, such as epoxy resins and silicone gels, suffer from poor thermal conductivity and lack self-healing properties. This study investigates liquid dielectric materials as alternative encapsulants, specifically Novec 7100, Vertrel XF, FC-3283, and Pastel NEO. These liquids, each exhibiting distinct dielectric and thermal properties, were applied to ceramic substrates. Partial discharge inception voltage (PDIV) measurements were conducted under a 60 Hz AC voltage, in conjunction with electric field analysis. The results indicate that high-permittivity insulating liquids can effectively modulate electric field distribution, thereby influencing PDIV. These findings suggest that appropriate selection of liquid encapsulants, based on dielectric strength and field relaxation characteristics, can enhance the insulation reliability of power modules.

DOI： 10.1109/ICDL63868.2025.11068273

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Evaluation of Dielectric and Insulation Properties of Various Fluorinated Liquids and Analysis Using Molecular Descriptors 査読有り国際誌

Suenaga S., Tomaiwa R., Okamoto T., Tsuchie M., Kawano S., Hikita M., Kozako M.

Proceedings IEEE International Conference on Dielectric Liquids 2025年01月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The objective of this study is to investigate the electrical properties of various fluorinated liquids, analyze them from multiple perspectives, and elucidate the impact of three-dimensional molecular structural differences on their electrical characteristics. The electrical properties of nine fluorinated liquids were compared. Additionally, the Pearson correlation coefficients were calculated between molecular descriptors - derived from SMILES representations - and breakdown voltage were determined. The results indicate that hexafluorobenzene and SS-110, which exhibited low relative permittivity and low DC conductivity, tended to have higher breakdown voltages. Furthermore, the molecular descriptors EState_VSA1, HallKierAlpha, and FpDensityMorgan2 demonstrated a strong correlation with breakdown voltage. These findings suggest that molecular descriptor calculations based on SMILES representations can serve as a useful tool for predicting the breakdown voltage (BDV) of fluorinated liquids. Moreover, this approach holds potential for estimating BDV values for unknown samples and contributing to the design of molecular structures with high dielectric strength.

DOI： 10.1109/ICDL63868.2025.11068220

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Power Line Communication Application for Enhanced Partial Discharge Monitoring: From Theory to Application 査読有り国際誌

Safura Lumba L., Kozako M., Hikita M., Sato H., Soeda M.

IEEE Transactions on Dielectrics and Electrical Insulation 31 ( 6 ) 2915 - 2921 2024年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Partial discharge (PD) activity is an important indicator of insulation health in high-voltage power apparatuses. Ensuring optimal functioning and timely equipment maintenance is crucial for operational efficiency and safety. This article introduces an innovative approach to equipment monitoring by utilizing power line communication (PLC) technology for detecting PD data. The novelty of this approach lies in the PLC receiver's dual capability to detect PD occurrences while simultaneously demodulating the PLC signal. This research analyzes the proposed low-cost, online PD monitoring system against traditional PD measurement techniques. Signals detectable by PLC were shown to propagate in PLC, allowing PLC to recognize PD from defect-simulated electrodes. To validate this, a simulated electrical substation circuit was constructed to facilitate the measurement of PD through the PLC system. The findings of this study indicate a good outcome for improving equipment monitoring procedures through the integration of PLC technology, providing a cost-effective alternative for continuous health assessment of electrical power equipment.

DOI： 10.1109/TDEI.2024.3425810

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Partial Discharge and Degradation Characteristics of Cast Resin Transformers Due to Bipolar Impulse Application 査読有り国際誌

Yao Y., Miyagawa M., Hikita M., Kozako M., Harada Y., Takei K., Ikeda M., Miyazaki K., Futakawa K.

IEEE Transactions on Dielectrics and Electrical Insulation 31 ( 6 ) 3489 - 3496 2024年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The objective of our work is to investigate partial discharge (PD) behaviors and degradation characteristics in winding insulation of an actual 22 kV cast resin transformer (CRTr) when subjected to bipolar impulse voltages. A differential high-frequency current transformer (HFCT) was employed on the high-voltage coils to measure PD pulses induced by impulse voltages. Additionally, PD measurement at ac voltage was carried out to characterize the aging process resulting from the application of bipolar impulses. Experimental findings indicated that higher-level bipolar impulses could cause large-amplitude PDs in the windings, occurring at the peak value of the applied impulse voltages and increasing with the number of applied impulses. PD inception voltage (PDIV) at ac voltage decreased to the operating voltage, and the discharge amplitude and phasewidth in phase-resolved PD (PRPD) patterns increased due to impulse PD occurrences. Considering these results, it is evident that the bipolar lightning impulses could cause large-amplitude PDs, intensify impulse PD activity, and ultimately lead to dielectric breakdown in the CRTr windings. Space charge accumulation and residual charge deposition resulting from impulse PD play a significant role in the generation and the process of development for impulse PDs in the winding insulation, contributing to an acceleration effect in the degradation process and eventual insulation failure.

DOI： 10.1109/TDEI.2024.3468249

Scopus

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Long-Term AC Partial Discharge Characteristics Till Dielectric Breakdown in an Aged 22 kV Cast Resin Transformer 査読有り国際誌

Miyagawa M., Yao Y., Kawano H., Hikita M., Kozako M., Harada Y., Takei K., Ikeda M., Miyazaki K., Futakawa K.

IEEE Transactions on Dielectrics and Electrical Insulation 31 ( 6 ) 3462 - 3468 2024年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

This article presents a trend analysis of long-term ac partial discharge (PD) characteristics till dielectric breakdown by accelerated degradation test in an aged 22 kV cast resin transformer (CRTr). The long-term ac PD characteristics till dielectric breakdown showed that the maximum PD charge Q<inf>max</inf> and the average PD charge Q<inf>mean</inf> increased sharply during the cumulative charging time t<inf>c</inf>, which was between 100 and 200 h before dielectric breakdown. These results suggest that defects could expand and propagate due to PD degradation and penetrate the insulating paper, resulting in large PD as a precursor to dielectric breakdown. With a voltage acceleration factor AF<inf>v</inf> and a frequency acceleration factor AF<inf>f</inf> in the accelerated degradation test considered, the time at which this sign was observed was well before dielectric breakdown. Therefore, this sign can be expected as one of the indicators of equipment replacement. The time sequence of ac PD characteristics just before dielectric breakdown was successfully measured. The result indicates the possibility that a fatal dielectric breakdown can be prevented owing to a fast interruption utilizing a circuit breaker. Furthermore, a breakdown site in the winding of the aged 22 kV CRTr could be located by the thermography, i.e., high electric field sections between the top block layers of the high-voltage side winding.

DOI： 10.1109/TDEI.2024.3425312

Scopus

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Partial Discharge Initiation Voltage Mechanism Improvement of Polyimide Film by Adding Boehmite Alumina Nanofiller under Impulse Voltage 査読有り国際誌

Arif A.I., Kozako M., Hikita M., Suwarno , Khayam U., Bando S., Hayashisaka N.

6th International Conference on Power Engineering and Renewable Energy Icpere 2024 Proceedings 2024年11月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Indonesia Bandung 2024年11月05日 - 2024年11月06日

One of the methods to assess the insulation's condition is measuring the partial discharge initiation voltage (PDIV). Researchers have examined the dielectric and insulating properties of polyimides (PI) and polyimides that have had boehmite alumina (BA) added. When the films are tested under impulse voltage, it is found that a PI film has a greater PDIV but a lower lifespan than a BA film. Using a finite element technique simulation on the atmospheric air wedge gap between the HV electrode and the polyimide film samples above the grounded electrode, the PDIV estimate in a computational model of the IEC (b) electrode system determines the electric field strength. At the intersection of the curve with Paschen's curve, the PDIV is found. The Dakin equation is used to validate the PDIV estimate process. Based on the additional nanofiller content, measurement and estimation findings verify that PI films have a greater PDIV than BA films and that they adhere to the Dakin's equation line. On the other hand, the BA films exhibit a greater PDIV at unipolar positive impulse voltage, indicating that the nanocomposite-added PI films are not the source of the initial electron emission.

DOI： 10.1109/ICPERE63447.2024.10845701

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Application of Multipurpose Intelligent Pulse Signal Generator in Cable PD Detection Technology Training 査読有り国際誌

Min C., Hikita M., Kozako M., Zhipeng Z., Yingying L.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024 ( 241 ) 41 - 44 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Korea Gangwon-do, 2024年10月20日 - 2024年10月24日

A multipurpose intelligent pulse signal generator that can simulate and generate various PD signal patterns and common interference noise has been developed to improve the partial discharge (PD) detection and localization skills of the professional team of operation and maintenance of power cable lines. It can simulate and generate various types of PD and noise signals similar to the measured signal spectrum in the test site and laboratory, including PD signal level, repetition rate, time interval, waveform, polarity, and PRPD pattern. It can not only provide some kinds of typical reference signals for verification of the signal identification functions and the calibration of PD detection devices, but also can be used with a simulated cable line model to form a training platform for developing PD detection and PD localization technology, which can also be applied to some technique competition of inspection and maintenance for cable line as well. Using this training and evaluation platform, it can simulate various signal patterns like the on-site signals of PD combined with noise under the safety environment without high voltage, such as background noise covering PD or multiple PD signals at the same time, to meet the training needs of testers to cope with various complex PD test problems on site, and it is also suitable for the learning and training of PD localization or cable fault localization based on traveling wave detection technology.

DOI： 10.23919/CMD62064.2024.10766232

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Propagation Characteristics of Surface Currents Induced by Partial Discharges in an Oil-filled Bushing on Transformer Tank 査読有り国際誌

Toyoda S., Miyagawa M., Hikita M., Kozako M., Kitoh Y., Sasaki M., Maekawa T., Aoki K.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024 ( 722 ) 665 - 668 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Korea Gangwon-do 2024年10月20日 - 2024年10月24日

The objective of this study is to determine the optimal placement of surface current sensors for detecting partial discharge (PD) in oil-filled bushings. To achieve this, the propagation characteristics of surface currents induced by PD events were investigated through both experimental and numerical approaches. The findings suggest that electromagnetic waves generated by PD escape from the bushing mounting flange to the outer wall surface of the tank and propagate at the speed of light along this surface. Additionally, the propagation of surface currents along the tank's outer wall appears to be influenced by the superposition of reflected waves from the tank's corners and bushing mounting flanges. By analyzing the difference in the arrival time of detection signals from multiple surface current sensors and the amplitude of the V0-<inf>p</inf> component, it was determined that the location of the PD can potentially be identified.

DOI： 10.23919/CMD62064.2024.10766300

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Polarity Effects of Residual Charge on Impulse PD of Three-Layer Polyester Films with a Void 査読有り国際誌

Yao Y., Miyagawa M., Nagatani Y., Hikita M., Kozako M.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024 ( 252 ) 727 - 730 2024年10月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Korea Gangwon-do 2024年10月20日 - 2024年10月24日

Partial discharge (PD) is a well-known characteristic associated with the presence of defects and electrical damage to the winding insulation of cast resin transformers. Previous studies have showed that the repetitive bipolar impulse voltage applications have a polarity effect on impulse PD generation and subsequent AC PD test. This paper aims to investigate the polarity effect of residual charge on impulse PD in three-layer polyethylene terephthalate (PET) film specimens with one void, subjected to multiple bipolar impulses. The results are discussed in terms of the residual surface charge on the specimens. Experimental results revealed that the impulse PD magnitude was higher under bipolar impulse applications compared to single polarity impulses. Surface charge mapping, which quantitatively characterizes the residual charge deposition on the sample, indicated that residual charges generated by an impulse PD occupied only a portion of the cavity surface, possibly due to the presence of discharge channels and the surface condition inside the cavity. Residual charge has a significant memory effect on subsequent PD behavior, influencing the distribution and magnitude of the next discharge channels in the defect walls. Based on these findings, it is suggested that repetitive bipolar impulses, due to the polarity effect of residual charge, are more likely to promote the aging of the transformer's insulation layer.

DOI： 10.23919/CMD62064.2024.10766280

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Investigation of the Relationship between Impulse Pre-stress and Subsequent AC Partial Discharge 査読有り国際誌

Nagatani Y., Miyazaki K., Kozako M., Hikita M., Miyake H., Tanaka Y., Fujii Y., Nakamura Y., Ito D., Nakamae T., Oyama K., Ozaki T.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024 ( 815 ) 744 - 747 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Korea Gangwon-do, 2024年10月20日 - 2024年10月24日

The primary objective of this study is to elucidate the mechanism of insulation degradation in cast resin transformers subjected to surge stress. To achieve this, it is essential to quantitatively assess the relationships among impulse pre-stress, subsequent AC partial discharge (PD) characteristics, and the degree of material degradation. In this paper, impulse pre-stress and subsequent AC PD characteristics were measured on void specimens. The results quantitatively demonstrate the relationship between the impulse PD charge and the total subsequent AC PD charge.

DOI： 10.23919/CMD62064.2024.10766165

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Investigation of Breakdown Strength and Dielectric Properties of Polypropylene/Polyolefin Elastomer Blends with Mixing Temperature 査読有り国際誌

Kim H., Shinozaki K., Hikita M., Kozako M., Lee O., Yu S.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024 ( 579 ) 738 - 740 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Korea Gangwon-do, 2024年10月20日 - 2024年10月24日

This study investigates DC breakdown strength and dielectric properties of polypropylene (PP)/polyolefin elastomer (POE) binary blends were investigated as a function of the mixing temperature. Mixing temperatures of 185, 195, 205, 215, 225, and 235°C were employed to alter the dispersed domain size of the POE within the PP matrix. The DC breakdown strength E<inf>b</inf> and dielectric properties of the PP/POE blend samples were measured at room temperature, with the relative complex permittivity ϵ<inf>r</inf>∗ evaluated across frequencies ranging from 1 Hz to 10 kHz. The PP/POE blend prepared at 185°C exhibited the highest DC breakdown strength as well as smallest real part of permittivity ϵ<inf>r</inf>'. A similar trend was observed for the imaginary part of permittivity ϵ<inf>r</inf>' across all samples. These results indicate that the mixing temperature significantly influences E<inf>b</inf>and dielectric properties, with the blend prepared at 185°C being particularly advantageous for enhancing the dielectric properties.

DOI： 10.23919/CMD62064.2024.10766336

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Improvement of Partial Discharge Initiation Voltage of Polyimide Film by Adding Boehmite Alumina Nanofiller 査読有り国際誌

Arif A.I., Kozako M., Hikita M., Suwarno , Khayam U., Bando S., Hayashisaka N.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024 ( 767 ) 222 - 225 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Korea Gangwon-do, 2024年10月20日 - 2024年10月24日

Measuring the insulation's partial discharge initiation voltage (PDIV) is advised in order to determine the insulation condition. The dielectric and insulating characteristics of a polyimide (PI) and polyimide with boehmite alumina (BA) added have been studied. It is discovered that a PI film has a higher PDIV but a lower lifetime than a BA film when the films are tested under impulse voltage. In an IEC (b) electrode system computational model, the PDIV estimation involves obtaining the electric field strength using a finite element method simulation on atmospheric air wedge gap between the HV electrode and the polyimide film samples above the grounded electrode. The PDIV is obtained at the point where the curve meets the Paschen's curve. PDIV estimation is continued by confirming to the Dakin equation. Measurement and estimation results confirm PI films have a higher PDIV than of BA films based on the nanofiller content added and conforms the Dakin's equation line. However, the BA films have a higher PDIV under unipolar positive impulse voltage which suggest the first electron emission doesn't start from the nanocomposite added PI films.

DOI： 10.23919/CMD62064.2024.10766117

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Feature Extraction Using Kullback-Leibler Divergence for Long-Term Trend Analysis of PRPD Patterns of Cast Resin Transformer 査読有り国際誌

Miyagawa M., Satake T., Kawano H., Hikita M., Kozako M., Harada Y., Takei K., Ikeda M., Miyazaki K., Futakawa K.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024 ( 1043 ) 785 - 788 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Korea Gangwon-do, 2024年10月20日 - 2024年10月24日

In the previous report, the partial discharge (PD) data of the aged 22 kV cast resin transformer (CRTr) till breakdown were obtained and the long-term PD trends were evaluated in general PD quantities such as PD repetition rate, but it was difficult to extract the changes to estimate the degradation state. Therefore, the purpose of this paper is to propose an optimal method of applying the Kullback-Leibler divergence (KL-D), which is a relatively easy method for quantifying changes in phase-resolved PD (PRPD) patterns, by focusing on several targets as reference values for KL-D and comparing the results. In this paper, KL-D was applied to the PRPD pattern of the long-term PD data of the aged 22 kV CRTr till breakdown to extract the amount of change. The results show that the PRPD pattern till dielectric breakdown of the aged 22 kV CRTr gradually changes as the accumulated time increased. This suggests on going degradation caused by PD within the insulation system. By leveraging KL-D for quantitative analysis, our study offers insights into the progression of degradation in CRTrs, paving the way for more precise monitoring and diagnosis of faults in these crucial power equipment systems.

DOI： 10.23919/CMD62064.2024.10766176

Scopus

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Effect of Changes in Partial Discharge Activity on Resin Erosion in Simulated Voids 査読有り国際誌

Aoki Y., Takeuchi K., Kozako M., Hikita M., Ito D., Oyama K., Nakamae T., Maeda T., Ozaki T.

2024 10th International Conference on Condition Monitoring and Diagnosis Cmd 2024 ( 427 ) 525 - 528 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Korea Gangwon-do, 2024年10月20日 - 2024年10月24日

Resin materials, widely used in insulating applications, are susceptible to partial discharge (PD) erosion. This degradation can result in insulation breakdown. Despite the recognized impact of PD on insulation materials, the detailed effects of varying discharge activity on resin erosion remain underexplored. To investigate the degradation of resin resulting from variations in the discharge activity caused by prolonged charging, an analysis was conducted on the resin surface structure within voids in response to changes in the discharge activity within the simulated voids. The V-Q Lissaj ous method was employed to measure the energy of the discharge inj ected into the voids. As the discharge energy increased with charging time, the discharge activity in the voids weakened, resulting in observable changes in the erosive structure of the resin surface. Prolonged exposure to discharge resulted in localized erosion growth, culminating in the formation of deep pore structures near the columnar structures within the eroded area of the polyethylene terephthalate (PET) owing to PD. The growth of these structures may be attributed to the variations in the crystallinity of the PET on the discharge eroded surface. The evolution of these degradation stages could be ascertained from the change in discharge energy per unit time, and the erosion depth per energy at each stage could be determined. This information can be used for a more accurate prediction of insulation lifetime. In PET, the phenomenon of increased PD resistance at PD eroded area was confirmed. This can lead to the selection and design of more resilient electrical insulation systems. The findings of this study can contribute to improving the reliability and safety of high-voltage equipment.

DOI： 10.23919/CMD62064.2024.10766243

Scopus

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Comparative Analysis between Measured and Simulated Pulse Voltage Distribution in Form Wound Stator Winding of Inverter-Fed Motors 査読有り国際誌

Miyazaki K., Nagatani Y., Kuno T., Hikita M., Kozako M., Iwanaga T., Zaizen K., Inoue Y., Yamada T., Okamoto T.

Annual Report Conference on Electrical Insulation and Dielectric Phenomena CEIDP ( 1A9 ) 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

USA Auburn, AL, 2024年10月06日 - 2024年10月09日

This paper presents a simulation study of a pulse voltage distribution within the windings of a motor using a high-frequency (HF) equivalent circuit model. The simulation results are validated by comparison with measured data, aimed at enhancing insulation design technology for next-generation inverter-fed motors. The investigation focuses on pulse voltage propagation between each coil-to-ground and turn-to-turn in the initial winding, which is crucial for selecting the optimal insulation design for evaluation. The subject of this study is an inverter-fed three-phase induction motor with a rated output of 75 kW and a rated voltage of 3kV<inf>rms</inf>. The winding configuration consists of two parallel wound types with 10 turns and 16 windings per phase, featuring 4 poles. The impulse voltage used had a rise time of 250 ns, a pulse width of 50μs, and a voltage amplitude of 1000 V. An impulse voltage was applied from the beginning to the end of Phase U, and output waveforms at each measurement point were obtained. Additionally, the output voltage waveforms for each turn were simulated using the developed HF equivalent circuit model, implemented in LTspice® (Analog Devices), a transient phenomenon simulation software, and compared with the measured results. The simulated results show good agreement with the measured results. The maximum simulated voltages matched measured values within an error margin of less than 3.7% for coil-to-ground and 9.5% for turn-to-turn in the initial winding. The developed HF equivalent circuit model is validated as a useful tool for evaluating surge voltage impacts in the insulation design of stator windings.

DOI： 10.1109/CEIDP61745.2024.10907706

Scopus

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Effect of Electric Field on Conductivity of Palm Fatty Acid Ester 査読有り国際誌

Okamoto T., Suenaga S., Tsuchie M., Hikita M., Kozako M.

Annual Report Conference on Electrical Insulation and Dielectric Phenomena CEIDP ( 2B5 ) 2024年10月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

USA Auburn, AL 2024年10月06日 - 2024年10月09日

Biodegradable ester oils have emerged as an environmentally sustainable alternative to traditional mineral oils in various applications. New uses, particularly in converter transformers, energy storage systems, and HVDC transformers, are under continuous investigation. The electrical conductivity of insulating materials is a key parameter for these novel applications; however, limited research has been conducted on the conductivity of biodegradable ester oils in comparison to mineral oil. This study examines the influence of electric field strength on the conductivity σ of palm fatty acid esters (PFAE) under DC voltage application ranging from 10 to 3000 seconds, and compares the results with those of mineral oil. The experimental results indicated that σ of PFAE decreases over time under electric fields ranging from 100 V/mm to 1 kV/mm, but increases with time under fields exceeding 1 kV/mm. Notably, the conductivity in long-term measurements was lower than in short-term measurements. When comparing the conductivities of PFAE, mineral oil, and synthetic esters, PFAE exhibited the highest conductivity across both short- and long-term measurements and various electric field strengths. This difference is attributed to the lower kinematic viscosity of PFAE compared to mineral oils and synthetic esters. The significant effect of kinematic viscosity on the conductivity was observed among the ester oils, with the ratio of conductivities closely matching the ratio of their kinematic viscosities. Furthermore, a comparison between ester oil and mineral oil revealed a more than 100-fold difference in conductivity, primarily due to the effect of ionic carrier conduction in the presence or absence of polar groups. Additionally, the higher charge density in ester-based insulating oils compared to mineral oils was identified as a contributing factor to this disparity.

DOI： 10.1109/CEIDP61745.2024.10907387

Scopus

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Breakdown Strength Comparison of Several Fluorinated Liquids with Different Molecular Structures 査読有り国際誌

Suenaga S., Okamoto T., Tsuchie M., Hikita M., Kozako M.

Proceedings of the IEEE International Conference on Properties and Applications of Dielectric Materials ( 281 ) 258 - 261 2024年08月

担当区分：最終著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Thailand Phuket 2024年08月04日 - 2024年08月07日

Fluorinated liquids are used as refrigerants and cleaning agents in various electrical equipment due to their excellent thermal, chemical, and electrical properties. However, the dielectric/insulating properties and breakdown mechanism of fluorinated liquids have not yet been clarified. Therefore, the authors compared the relative permittivity, dissipation factor and breakdown voltage of five fluorinated liquids with different molecular structures: HFE-7100 (C<inf>4</inf>F<inf>9</inf>OCH<inf>3</inf>), HFE-356mmz ((CF<inf>3</inf>)<inf>2</inf>CHOCH<inf>3</inf>), HFE-356mec (CF<inf>3</inf>CHFCF<inf>2</inf>OCH<inf>3</inf>), HFC-43-10mee (CF3CHFCHFCF2CF3) and Hexafluorobenzene (C6F6). This paper will help to discuss the effect of different molecular structures on the insulating properties. The relative permittivity and dissipation factor was measured using a liquid electrode and an LCR meter at an applied voltage of 1 V AC, a frequency of 60 Hz, and room temperature. The highest relative permittivity for HFE-356mmz was about 48.1 and the lowest for Hexafluorobenzene was 1.98. Similarly, the highest dissipation factor for HFE-356mmz was 18.621 and the lowest dissipation factor for Hexafluorobenzene was 0.0096. The breakdown voltage (BDV) was boosted at AC 3 kV/s and 15 points were obtained for each sample at 1 mm and 2.5 mm gap. Hexafluorobenzene was found to have a higher BDV than the other samples. From these results, it was found that Hexafluorobenzene, which had a smaller relative permittivity, had a higher BDV. In addition, HFE-7100, HFE-356mmz, HFE-356mec, and HFC-43-10mee, it was considered that bubbles were generated in the samples by Electro Hydro Dynamics (EHD) generated during high voltage charging, and that these bubbles entered between the electrodes, causing the breakdown voltage to decrease.

DOI： 10.1109/ICPADM61663.2024.10750631

Scopus

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Breakdown Characteristics of Insulating Oil in Uniform to Non-uniform Electric Field under AC Voltage 査読有り国際誌

Yoshida S., Yamatake A., Kozako M., Hikita M.

Proceedings of the 2024 IEEE 5th International Conference on Dielectrics Icd 2024 ( 1C-01 ) 2024年06月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

France Toulouse, 2024年06月30日 - 2024年07月04日

It is imperative that insulation designers understand breakdown voltage (BDV). BDV of transformer oil are generally understood to follow stressed oil volume (SOV) theory. However, estimating more than 90% stressed oil volume in non-uniform electric fields in a transformer is extremely time consuming. Therefore, we propose a prediction formula that can estimate the BDV of insulating oil easily. In this study, the breakdown characteristics of insulating oil were investigated in a non-uniform electric field under AC voltage application. Experimental results were obtained with those several bare electrodes and oil gap lengths. As a result, it was derived that a prediction formula represented by √UE<inf>max</inf> =25.3d•0.28 in the mineral oil and ester oil. It was also confirmed that experimental results matched to the prediction curve and could easily estimate the breakdown voltage.

DOI： 10.1109/ICD59037.2024.10613251

Scopus

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Simultaneous Measurement of Space Charge Distribution and Partial Discharge by PEA Method 査読有り国際誌

Endo K., Kondo K., Kobayashi J., Miyake H., Tanaka Y., Kozako M., Hikita M.

Proceedings of the 2024 IEEE 5th International Conference on Dielectrics Icd 2024 ( 3C-18 ) 2024年06月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

France Toulouse 2024年06月30日 - 2024年07月04日

In order to improve the efficiency of inverter-driven motors, it is required to prevent partial discharge, and it has been pointed out that PDIV may be lowered during operation due to the space charge that accumulates in the insulation material used to coat the windings. However, there have been few experimental attempts to demonstrate this effect. Therefore, in this study, the effect of space charge accumulation in insulating materials on PD characteristics was verified by the pulsed electroacoustic (PEA) metho. As a result, it was clarified that the space charge accumulation influences PDIV degradation.

DOI： 10.1109/ICD59037.2024.10613200

Scopus

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Identification of Defect Type in an Aged 22 kV Cast Resin Transformer from Phase-Resolved PD Patterns 査読有り国際誌

Miyagawa M., Yao Y., Satake T., Kawano H., Hikita M., Kozako M., Harada Y., Takei K., Ikeda M., Miyazaki K., Futakawa K.

Proceedings of the 2024 IEEE 5th International Conference on Dielectrics Icd 2024 ( 2B-13 ) 2024年06月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

France Toulouse 2024年06月30日 - 2024年07月04日

This paper presents identification of defect type in the insulation system of an aged 22 kV cast resin transformer (CRTr) from comparing phase-resolved partial discharge (PRPD) patterns with those in different electrode systems simulating various kinds of defects. Quantitative analysis of the PRPD patterns was performed using a measure of the difference between the two probability distributions, called the Kullback-Leibler (KL) divergence. Comparison of PRPD patterns using KL divergence value (KL-D) suggested the possibility that a defect type in the aged 22 kV CRTr was attributed to inter-layer voids. Furthermore, even for the PRPD pattern of CRTr, which had little apparent change over time, the value of KL-D increased with increasing cumulative application time tc. As a result, it can be said that KL divergence is a useful index in comparing PRPD patterns quantitatively.

DOI： 10.1109/ICD59037.2024.10613342

Scopus

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Effect of Elastomer Blend on High Temperature Dielectric Properties of Polypropylene 査読有り国際誌

Kim H., Shinozaki K., Hikita M., Kozako M., Yu S.

Proceedings of the 2024 IEEE 5th International Conference on Dielectrics Icd 2024 ( 2A-21 ) 2024年06月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

France Toulouse 2024年06月30日 - 2024年07月04日

This paper presents investigation on dielectric properties of polypropylene (PP), binary blend (iPP/EOC=4.4:5.6), and ternary blend 1 (iPP/EOC/PPC=4:5:1), and ternary blend2 (iPP/EOC/PPC=3.6/4.6/1.8) at high temperatures up to 150°C. EOC and PPC stand for ethylene-octene copolymers and EPR dispersed in PP, respectively. The relative complex permittivity ϵ<inf>r</inf>∗ = ϵ<inf>r</inf>′ -jϵ<inf>r</inf>′′ and AC conductivity σ<inf>ac</inf> were measured in a temperature range from 30°C to 150°C at frequencies from 1 Hz to 10 kHz. Experimental results revealed that the real part ϵ<inf>r</inf>′ of the relative permittivity of all kinds of material decreased with increasing temperature, though pristine PP exhibited a smallest decrease in ϵ<inf>r</inf>′ with temperature. While the imaginary part ϵ<inf>r</inf>′′ exhibited a linear decrease with the frequency in the log vs log plot below 1 kHz and above 100°C for binary blend, ternary blend1 and 2. The results indicate that the EOC addition to PP is contributed to the increase in the complex permittivity. It was also found that σ<inf>ac</inf> of binary blend, ternary blend1, and 2 remained constant below 1 kHz and above 110°C, while σ<inf>ac</inf> of all the samples increased proportionally with frequency above 1 kHz. The calculated activation energies derived from the temperature dependence of the DC conductivity of binary blend, ternary blend 1, and ternary blend 2 were 0.602, 0.849, and 0.791 eV, respectively, with ternary blend 1 having the largest activation energy. Ternary blend 1 with the largest value was considered the most likely to inhibit carrier transport.

DOI： 10.1109/ICD59037.2024.10613350

Scopus

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Comparison of High Temperature Dielectric Properties between Epoxy Resins with Alicyclic and Bisphenol A 査読有り国際誌

Shinozaki K., Hikita M., Kozako M., Ueshima M.

Proceedings of the 2024 IEEE 5th International Conference on Dielectrics Icd 2024 ( 2A-18 ) 2024年06月

担当区分：責任著者記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

France Toulouse 2024年06月30日 - 2024年07月04日

The purpose of this study is to elucidate the dielectric properties of alicyclic epoxy resins at elevated temperatures. Compared to common bisphenol A epoxy resins, alicyclic epoxy resins have a higher glass transition temperature and lower viscosity in the liquid state. Therefore, alicyclic epoxy resins are expected to exhibit good dielectric properties in high temperature environments. In this paper, we compare the dielectric properties of alicyclic epoxy resins and bisphenol A epoxy resins from room temperature to high temperature.

DOI： 10.1109/ICD59037.2024.10613347

Scopus

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Effect of electric field on conductivity of synthetic ester 査読有り国際誌

Rui Yu, Shanika Matharage, Daigo Okumura, Motoo Tsuchie, Masahiro Kozako, Masayuki Hikita, Zhongdong Wang

IET Conference Proceedings ( The Institution of Engineering and Technology ) 2023 ( 46 ) 68 - 72 2024年04月

Long-term AC partial discharge characteristics of a 22 kV cast resin transformer in accelerated tests 査読有り国際誌

Mizuki Miyagawa, Yuanhang Yao, Ryota Koresawa, Hideaki Kawano, Masayuki Hikita, Masahiro Kozako, Katsutoshi Takei, Teruo Shibata, Tamotsu Uzuki, Kazuhiro Futakawa

IET Conference Proceedings ( The Institution of Engineering and Technology ) 2023 ( 46 ) 1127 - 1131 2024年04月

Partial discharge characteristics to breakdown in cast resin transformer suffering lightning impulses to accelerate aging 査読有り国際誌

Yuanhang Yao, Mizuki Miyagawa, Ryota Koresawa, Masahiro Kozako, Masayuki Hikita, Katsutoshi Takei, Teruo Shibata, Tamotsu Uzuki, Kazuhiro Futakawa

IET Conference Proceedings ( The Institution of Engineering and Technology ) 2023 ( 46 ) 538 - 542 2024年04月

Application of power line communication for online partial discharge monitoring in a simulated substation 査読有り国際誌

Lunnetta Safura Lumba, Akito Houdai, Masahiro Kozako, Masayuki Hikita, Hidefumi Sato, Masahiro Soeda

IET Conference Proceedings ( The Institution of Engineering and Technology ) 2023 ( 46 ) 482 - 487 2024年04月

Impedance Frequency Analysis of Stator Winding of Electric Motors using Highfrequency Equivalent Circuit 査読有り

K.Miyazaki, T.Kuno, M.Hikita, M.Kozako, T.Okamoto, Y.Inoue, K.Zaizen, T.Yamada, T.Iwanaga

2023 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( 2B9 ) 383 - 386 2023年10月

Improvement of Partial Discharge Signal Recognition for Power Cable Lines 査読有り国際誌

M.Chen, M.Kozako, M.Hikita, N.Takeuchi, Z.Zhou, J.Lu

2023 International Symposium on Electrical Insulating Materials (ISEIM) ( A-1 ) 2023年09月

Digest Report of Cooperative Research Committee on EINA Magazine 査読有り国際誌

Y.Tanaka, M.Kozako, N.Fuse

2023 International Symposium on Electrical Insulating Materials (ISEIM) ( DR-1 ) 2023年09月

Effect of Moisture Content on Temperature Dependence of Partial Discharge Characteristics of Biodegradable Ester Oils 査読有り国際誌

T.Okamoto, D.Okumura, M.Tsuchie, M.Hikita, M.Kozako

2023 International Symposium on Electrical Insulating Materials (ISEIM) ( MVP4-6 ) 2023年09月

Effect of Carbon Black Addition on Dielectric Breakdown Strength of Alicyclic Epoxy Resins 査読有り国際誌

K.Shinozaki, D.Okumura, M.Hikita, M.Kozako

2023 International Symposium on Electrical Insulating Materials (ISEIM) ( MVP3-5 ) 2023年09月

LiquidLong-Term Partial Discharge Characteristics till Breakdown in a 22 kV Cast Resin Transformer 査読有り国際誌

M.Miyagawa, Y.Yao, R.Koresawa, H.Kawano, M.Hikita, M.Kozako

2023 International Symposium on Electrical Insulating Materials (ISEIM) ( MVP1-5 ) 2023年09月

Partial Discharge Detection and Analysis on a Cast Resin Transformer under Lightning Impulse Voltage 査読有り国際誌

Y.Yao, M.Miyagawa, R.Koresawa, M.Kozako, M.Hikita, K.Takei, T.Shibata, T.Uzuki, K.Futakawa, H.Ozeki

2023 International Symposium on Electrical Insulating Materials (ISEIM) ( F-4 ) 2023年09月

Observation of Changes in Partial Discharge Activity in Artificial Voids Based on Analysis of Φ-q-n Characteristics and Light 査読有り国際誌

Y.Aoki, Y.Takeuchi, T.Sakakihara, K.Iida, T.Umemura, M.Kozako

2023 International Symposium on Electrical Insulating Materials (ISEIM) ( P-8 ) 2023年09月

Application of Power Line Communication for Online Partial Discharge Monitoring in A Simulated Substation 査読有り国際誌

Lunnetta Safura Lumba, Akito Houdai, Masahiro Kozako, Masayuki Hikita, Hidefumi Sato, Masahiro Soeda

The 23rd International Symposium on High Voltage Engineering(ISH2023) ( O7.1.05 ) 2023年08月

Effect of Electric Field on Conductivity of Synthetic Ester 査読有り国際誌

Rui Yu, Shanika Matharage, Daigo Rui Yu, Shanika Matharage, Daigo Okumura, Motoo Tsuchie, Masahiro Kozako, Masayuki Hikita, Zhongdong Wang

The 23rd International Symposium on High Voltage Engineering(ISH2023) ( O10.1.06 ) 2023年08月

Partial Discharge Characteristics to Breakdown in Cast Resin Transformer Suffering Lightning Impulses to Accelerate Aging 査読有り国際誌

Y.Yao, M.Miyagawa, R.Koresawa, M.Kozako, M.Hikita, K.Takei, T.Shibata, T.Uzuki, K.Futakawa

The 23rd International Symposium on High Voltage Engineering(ISH2023) ( O8.1.05 ) 2023年08月

Long-Term AC Partial Discharge Characteristics of A 22 kV Cast Resin Transformer in Accelerated Tests 査読有り国際誌

M.Miyagawa1, Y.Yao, R.Koresawa, H.Kawano, M.Hikita, M.Kozako, K.Takei, T.Shibata, T.Uzuki, K.Futakawa

The 23rd International Symposium on High Voltage Engineering(ISH2023) ( O8.1.04 ) 2023年08月

Effect of Moisture Content on Temperature Characteristics of Dielectric Breakdown Strength of Biodegradable Ester Oils 査読有り

T.Okamoto, D.Okumura, K.Hamasuna, M.Kozako, M.Hikita, M.Tsuchie, M.Maharana, C.Olmo

22nd IEEE International Conference on Dielectric Liquids (ICDL2023) ( 191 ) 2023年06月

Impact of Thermal Aging on The Conductivity of Kraft Paper Impregnated with Mineral Oil and Synthetic Ester 査読有り

T.Okamoto, D.Okumura, K.Hamasuna, M.Kozako, M.Hikita, M.Tsuchie, M.Maharana, C.Olmo

22nd IEEE International Conference on Dielectric Liquids (ICDL2023) ( 196 ) 2023年06月

Partial Discharge Characteristic Analysis in a 6.6 kV Cast Resin Voltage Transformer Using High-Frequency Distributed Constant Equivalent Circuits 査読有り

R.Koresawa, M.Kozako, M.Hikita, Y.Aoki, K.Iida, T.Umemura, D.Ito, K.Oyama, T.Nakamae, T.Maeda, T.Ozaki

2023 Electrical Insulation Conference (EIC) 87 - 91 2023年06月

Proposal for Evaluation of Insulation Performance by Partial Discharge Characteristics of Resin Substrates Containing Micro-Sized Multiple Voids 査読有り

D.Okumura, T.Okamoto, M.Kozako, M.Hikita

2023 Electrical Insulation Conference (EIC) 121 - 124 2023年06月

Application of ANFIS and ANN for Partial Discharge Localization in Oil Through Acoustic Emission 査読有り国際誌

Hashim A.H.M., Azis N., Jasni J., Radzi M.A.M., Kozako M., Jamil M.K.M., Yaakub Z.(プトラ大学・マレーシア）

IEEE Transactions on Dielectrics and Electrical Insulation ( The IEEE Dielectrics and Electrical Insulation society ) 30 ( 3 ) 1247 - 1254 2023年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

This article presents an examination on the acoustic partial discharge (PD) localization in oil based on adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) approaches. Impedance matching circuit (IMC) was used to measure the electrical PD. The acoustic PD was obtained through an acoustic emission (AE) sensor and preamplifier gain unit. In total, 112 coordinates for each of the AE sensors were utilized to evaluate the location of the PD. Once the voltage reached 30 kV, the electrical and acoustic PDs were recorded. Next, the data were preprocessed by moving average (MA) and analyzed by time of arrival (TOA), ANFIS, and ANN. The distance between PD and AE sensor was calculated based on TOA to determine the PD location. These information were used as an input to train the network by optimizing epoch and neuron for ANFIS and ANN in order to locate PD. ANFIS has the best percentage of PD source prediction based on root mean square error (RMSE) and coefficient of determination (R2) as compared to ANN. Meanwhile, the computation time for ANN is 1.75 s faster than ANFIS to perform PD localization based on AE PD signals.

DOI： 10.1109/TDEI.2023.3264958

Scopus

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Enhancement of Electrical Insulation Performance using FGM Techniques in Air Insulated HV GIS 査読有り国際誌

K.Okamoto, H.Masui, H.Yanase, N.Hayakawa, K.Kato, H.Okubo, M.Kozako, N.Osawa, T.Inoue, K.Adachi

Joint CIGRE SC B3 & A3 Colloquium 2023 ( PS3 ) 2023年05月

鉱油中における熱および課電加速劣化したポリビニルホルマール線の絶縁特性査読有り

善田優希, 小迫雅裕, 匹田政幸, 大久保祐輔, 下村好亮, 田中剛

電気学会論文誌A 143 ( 3 ) 98 - 104 2023年03月

Online and Offline Partial Discharge Measurement in Rotating Machines using Transient Earth Voltage Sensors 査読有り国際誌

Lunnetta Safura Lumba, Akito Houdai, Ryota Koresawa, Tsutomu Kuno, Masahiro Kozako, Masayuki Hikita, Kenta Yonemura

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( B1-3 ) 2022年11月

AC Partial Discharge Measurements of Aged Cast Resin Transformers after Multiple Impulse Voltage Applications 査読有り国際誌

Y.Yao, M.Kozako, R.Koresawa, H.Kawano, M.Hikita, K.Takei, M.Sato, K.Futakawa, H.Sato

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P4-25 ) 2022年11月

Investigation of saturation moisture in the PD behavior in the biodegradable ester oil 査読有り国際誌

M.Maharana, K.Hamasuna, M.Kozako, M.Hikita, M.Tsuchie, K.Wu

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P4-12 ) 2022年11月

Partial Discharge Degradation Analysis from Light Emission Observation and Partial Discharge Characteristic Measurement by Partial Discharge in Artificial Defects Using 査読有り国際誌

Y.Aoki, Y.Takeuchi, T.Sakakihara, K.Ida, T.Umemura, M.Kozako, M.Hikita, T.Nakamae, T.Maeda, T.Ozaki

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P3-25 ) 2022年11月

A Study of PRPD Statistics to Improve the Performance of PD Detection and Defect Type Identification 査読有り国際誌

R.Kai, T.Yamanoue, H.Tanaka, H.Kawano, M.Kozako, M.Hikita

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P3-24 ) 2022年11月

Investigation on Dominant Frequency of Partial Discharge Current in 6.6 kV Cast Resin Voltage Transformer 査読有り国際誌

R.Koresawa, M.Kozako, M.Hikita, Y.Aoki, K.Iida, T.Umemura, T.Nakamae, T.Maeda, T.Ozaki

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P3-21 ) 2022年11月

Long term on-line PD monitoring using power line communication in a distribution substation 査読有り国際誌

A.Houdai, Lunnetta Safura Lumba, T.Wakisaka, M.Kozako, M.Hikita, H.Sato, M.Soeda

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P3-20 ) 2022年11月

Investigation of Microvoid Detection in Insulating Resin Substrates Based on Partial Discharge Characteristics 査読有り国際誌

K.Hamasuna, D.Okumura, M.Kozako, M.Hikita

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P3-17 ) 2022年11月

Impulse Pre-stress Effect on AC Partial Discharge Inception Characteristics of Winding Model Sample 査読有り国際誌

Y.Zenda, M.Kozako, M.Hikita, Y.Fujii, H.Cho, Y.Nakamura

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P3-15 ) 2022年11月

Electrical Conduction Properties of Titanium Added Aluminum Nitride Substrates at High Temperatures and Electric Fields 査読有り国際誌

D.Okumura, K.Hamasuna, M.Kozako, M.Hikita, T.Nagami, K.Yamamoto

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( P2-16 ) 2022年11月

Study of the Thermal Degradation of Different Insulating Papers Impregnated with a Natural Ester 査読有り国際誌

Cristina Méndez Gutiérrez, Cristian Olmo Salas, Carlos Javier Renedo Estébanez, Masahiro Kozako, Masayuki Hikita, Alfredo Ortiz Fernández

9th International Conference on Condition Monitoring and Diagnosis (CMD2022) ( A2-5 ) 2022年11月

ボイド含有ポリエステルフィルムの交流部分放電特性に及ぼすインパルス前課電の影響査読有り

柳瀬博雅, 満留博, 岡本健次, 小迫雅裕, 匹田政幸

電気学会論文誌A 142 ( 9 ) 375 - 380 2022年09月

High Temperature Dielectric Properties of Aluminum Nitride Substrates with Different Amounts of Titanium 査読有り国際誌

D.Okumura, K.Hamasuna, M.Kozako, M.Hikita, T.Nagami, K.Yamamoto

International Workshop on Integrated Power Packaging 2022 (IWIPP) ( 5011 ) 2022年08月

大学間連携討論型オンライン授業の実施査読有り

宮内肇, 末廣純也, 小迫雅裕, 西田貴司, 井上昌睦

工学教育 70 ( 4 ) 160 - 164 2022年07月

Prediction of Lifetime in Surge Resistant Enamel Twisted Pair by Partial Discharge Degradation under Repetitive Impulse Voltage Application 査読有り

M.Kozako, Y.Zenda, S.Kodama, M.Hikita, N.Hayashizaka, N.Fujimoto, H.Kikuchi

4th IEEE International Conference on Dielectrics (ICD2022) ( 1b-1 ) 2022年07月

Insulation Properties of Twisted-pair of Polyvinyl Formal Wires with Artificial Pinhole and Thermal Stress in Mineral Oil 査読有り

Y.Zenda, S.Kodama, M.Kozako, M.Hikita, Y.Okubo, K.Shimomura, T.Tanaka

4th IEEE International Conference on Dielectrics (ICD2022) ( 3c-6 ) 2022年07月

Partial Discharge Monitoring and Diagnosis Utilizing Power Line Communication in a Simulated Substation 査読有り

A.Houdai, R.Koresawa, T.Wakisaka1, M.Kozako, M.Hikita, H.Sato, M.Soeda

2022 Electrical Insulation Conference (EIC) ( PS1-7 ) 132 - 135 2022年06月

Effect of Winding Insulation Thickness on Partial Discharge Degradation and Life Characteristics of Enamel Twisted Pair 査読有り

S.Kodama, Y.Zenda, M.Kozako, M.Hikita, N.Hayashizaka, H.Kikuchi

2022 Electrical Insulation Conference (EIC) ( PS2-14 ) 225 - 228 2022年06月

Partial discharge detection of cast resin transformers using high-frequency signal propagation characteristic analysis and application to diagnostic technology 査読有り

R.Koresawa, M.Kozako, M.Hikita, Y.Aoki, K.Iida, T.Umemura, T.Nakamae, T.Maeda, T.Ozaki, Y.Nakamura

2022 Electrical Insulation Conference (EIC) ( PS2-4 ) 182 - 185 2022年06月

AC Partial Discharge Characteristics in Ester Oil/Pressboard Composite Insulation System with Metallic Protrusion 査読有り

K.Hamasuna, M.Kozako, M.Hikita, S.Yoshida, Y.Yamanaka, T.Umemoto

21th IEEE International Conference on Dielectric Liquids (ICDL2022) ( 108 ) 196 - 199 2022年05月

ナノコンポジットエナメル線における絶縁破壊までの部分放電特性と周波数加速等価性査読有り

竹之内将, 善田優希, 小迫雅裕, 匹田政幸, 藤本信貴, 林坂徳之, 加藤俊彦, 菊池英行

電気学会論文誌A 142 ( 5 ) 208 - 214 2022年05月

Partial Discharge Localization in Oil Through Acoustic Emission Technique Utilizing Fuzzy Logic 査読有り国際誌

Ahmad Hafiz Mohd Hashim, Norhafiz Azis, Jasronita Jasni, Mohd Amran Mohd Radzi, Masahiro Kozako, Mohamad Kamarol Mohd Jamil, Zaini Yaakub

IEEE Transactions on Dielectrics and Electrical Insulation 29 ( 2 ) 623 - 630 2022年04月

位相分解部分放電パターン再構築とニューラルネットワークによる変電所の絶縁診断査読有り

藤岡駿弥, 河野英昭, 小迫雅裕, 匹田政幸, 枝修, 谷口修平, 椎名康晴

電気学会論文誌A 142 ( 3 ) 94 - 100 2022年03月

エポキシ樹脂のナノシリカ添加および熱処理における二次電子放出特性査読有り

小森あかね, 永田浩二郎, 佐藤孔亮, 三宅弘晃, 田中康寛, 小迫雅裕, 匹田政幸

電気学会論文誌A 142 ( 3 ) 118 - 115 2022年03月

Development of Innovative Functional Electrical Insulating Composites 査読有り国際誌

M.Hikita, M.Kozako

JOURNAL OF Engineering Science and Technology Review ( 14 ) 2022年01月

Partial Discharge Degradation Mechanism of Nanocomposite Enameled Twisted Pair under Repetitive Impulse Voltage Application 査読有り

S.Takenouchi, Y.Zenda, M.Kozako, M.Hikita, N.Fujimoto, N.Hayashizaka, T.Kato, H.Kikuchi

2021 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( C-6 ) 69 - 72 2021年12月

Effect of Temperature on RPDIV of Enamel Twisted Pair under Repetitive Impulse Voltage Application with Different Rise Time 査読有り

Y.Zenda, S.Takenouchi, M.Kozako, M.Hikita T.Okamoto, S.Jintong, A.Izumi, K.Karasawa

2021 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( 3D-10 ) 648 - 651 2021年12月

Characteristics of Breakdown Strength of Hydrocarbon Thermosetting Resin in Low Temperature Environment 査読有り

T.Matsuki, Y.Inoue, K.Hamasuna, M.Kozako, M.Hikita, N.Fukumoto, N.Kamei

2021 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( 3D-4 ) 623 - 626 2021年12月

Effects of Nano-micro Composite and Shielding on Flashover Characteristics of Gas Insulated Switchgear Spacer Model in Different Lightning Impulse Application Methods 査読有り

Y.Inoue, M.Kozako, M.Hikita, H.Masui, H.Yanase, K.Okamoto

2021 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( 3A-5 ) 471 - 474 2021年12月

A Study on Simultaneous Measurements of PD Light Emission and Charge in Resin Substrate 査読有り

K.Hamasuna, M.Kozako, M.Hikita

2021 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( 1C-15 ) 307 - 310 2021年12月

Volume Effect on AC Dielectric Breakdown Strength of Ester Oil Compared with that of Mineral Oil 査読有り

K.Hamasuna, T.Matsuki, M.Kozako, M.Hikita, S.Yoshida, H.Hamada, T.Umemoto

The 22th International Symposium on High Voltage Engineering(ISH2021) ( 748 ) 2021年11月

Research Trends in Online Partial Discharge Monitoring and Diagnosis Utilizing ICT in Electric Power Equipment 招待有り査読有り

M.Hikita, M.Kozako

2021 3rd International Conference on High Voltage Engineering and Power Systems (ICHVEPS) ( PS1-3 ) 6 - 13 2021年10月

モールド変圧器のインピーダンス周波数特性の解明と部分放電診断手法査読有り

柿本康朝, 小迫雅裕, 匹田政幸, 飯田和生, 梅村時博, 中村勇介, 中前哲夫, 前田照彦, 尾崎多文

電気学会論文誌A 141 ( 7 ) 420 - 427 2021年07月

S6ガス中楔ギャップのインパルス部分放電開始特性に及ぼすエポキシ複合材へのナノフィラー添加の影響査読有り

井上好之, 大角浩太郎, 小迫雅裕, 匹田政幸, 増井秀好, 満留博, 柳瀬博雅, 岡本健次

電気学会論文誌A 141 ( 6 ) 391 - 397 2021年06月

Effect of Different Types of Fullerene Addition on AC Dielectric Breakdown Strength of Epoxy Resin 査読有り

Ozuno K., Inoue Y., Kozako M., Hikita M., Igarashi T., Kaji H.

IEEE Transactions on Dielectrics and Electrical Insulation 28 ( 2 ) 625 - 629 2021年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

This research intends to investigate the applicability of fullerene as an electrically insulating filler. So far, the authors reported that the addition of a very small amount of fullerene C60 to epoxy resin (EP) improves the dielectric breakdown strength $(E_{\mathrm{b}})$ by about 30%. This report presents the study on the effect of four different types of fullerenes as fillers added to EP on the improvement of $E_{\mathrm{b}}$. Fullerenes used are mixtures of C60 and higher order one $\mathrm{C}_{70}$ with a different mixture rate, and the addition effect of sublimation-purified fullerene on $E_{\mathrm{b}}$ is also investigated. Experimental results reveal that samples added with sublimated fullerenes exhibit larger $E_{\mathrm{b}}$ than that of samples without sublimation. The sublimation-purified sample is also found to give almost no difference in $E_{\mathrm{b}}$ by the type or proportion of the added fullerenes $\mathrm{C}_{60}$ and $\mathrm{C}_{70}$. An attempt is also made to discuss the mechanism of the improvement effect on $E_{\mathrm{b}}$ of fullerene by evaluating the electronic state of epoxies with different fullerene fillers and curing agent using quantum chemical calculation. As a result, it is shown that the introduction of $\mathrm{C}_{60}$ and $\mathrm{C}_{70}$ into the EP considering the curing agent introduces electron traps of 0.64 and 0.72 eV, respectively. It is interpreted that the introduced electron traps suppress the electron avalanche, and consequently improves the breakdown strength.

DOI： 10.1109/TDEI.2021.009360

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85104652991&origin=inward

Characteristics of Creepage Discharge in Oil/Pressboard Composite Insulation 査読有り

Yoshida S., Kozako M., Hikita M.

IEEE Transactions on Dielectrics and Electrical Insulation 28 ( 2 ) 608 - 615 2021年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

This paper deals with partial discharge characteristics in oil/pressboard composite insulation system, which is used in oil-immersed power transformer. It is found that the discharge propagates in the same route on the pressboard surface as in the previous discharge every time under repeated impulse voltage application. We also revealed that the white trace remained along the path of discharge and affected the subsequent discharge progress because of being a weak point part on insulation. This study presents an investigation of the effect of the white trace on partial discharge inception voltage (PDIV) of the composite insulation system with high-speed optical observation and electrical measurements for the discharge propagation. The discharge propagation mechanism is also discussed with comparing the discharge progress characteristics before and after the white trace formation.

DOI： 10.1109/TDEI.2020.009313

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85104654786&origin=inward

2A15 大学間連携オンライン討論型授業の実施査読有り

末廣純也, 小迫雅裕, 宮内肇, 西田貴司, 井上昌睦

工学教育研究講演会講演論文集 ( 公益社団法人日本工学教育協会 ) 2021 ( 0 ) 138 - 139 2021年01月

九州支部における年次活動査読有り

小迫雅裕

電気学会誌 ( 一般社団法人電気学会 ) 140 ( 12 ) 795 - 795 2020年12月

担当区分：筆頭著者記述言語：日本語掲載種別：記事・総説・解説・論説等（学術雑誌）

はじめに九州支部は，福岡，佐賀，長崎，大分，熊本，宮崎，鹿児島，沖縄（沖縄支所設置）の8県から構成され，その会員数は2020年3月末で1,377名（名誉員1名，終身員87

DOI： 10.1541/ieejjournal.140.795

CiNii Article

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/ieejjournal/140/12/140_795/_pdf

Construction and Experimental Verification of Novel Online Partial Discharge Monitoring System Using Power Line Communication 査読有り

Kakimoto Y., Yoshikawa H., Jogo T., Wakisaka T., Kozako M., Hikita M., Sato H., Tagashira H., Soeda M.

IEEE Transactions on Dielectrics and Electrical Insulation 27 ( 6 ) 2165 - 2171 2020年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 1994-2012 IEEE. In this research, we aim to construct a completely new partial discharge (PD) monitoring system that applies inexpensive power line communication (PLC). We have proposed a PD detection method and monitoring system (PDMS-PLC) on the basis of PLC signal transfer rare is affected by an error due to disturbance. An attempt is made to identify PD source from the quadrant dependence of information transmission rate (hereinafter referred to PHY rate [Mbps]) by selecting a pair of quadrants of applied voltage phase; i.e. 1st and 3rd quadrants, or 2nd and 4th ones. It was found that the PHY (Abbreviation for the lowest physical layer in the OSI (open systems interconnection) hierarchical model.) rate number distribution reflects the PD characteristics obtained by the phase resolved PD (PRPD) pattern. Environmental noise level is also measured at an actual substation using PDMS-PLC. Consequently, the applicability of PDMS-PLC to PD signal detection and defect type identification is suggested.

DOI： 10.1109/TDEI.2020.009081

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85098012216&origin=inward

Digest Report of Cooperative Research Committee on EINA Magazine Publication 査読有り

Y.Kakimoto, H.Yoshikawa, T.Jogo, T.Wakisaka, M.Kozako, M.Hikita, H.Sato, M.Soeda, H.Tagashira

The 2020 International Conference on Condition Monitoring and Diagnosis (CMD2020) ( 457 ) 2020年10月

Long-term Online Partial Discharge Trend Monitoring for Cast Resin Transformers in Switchboard 査読有り

Y.Kakimoto, T.Jogo, M.Kozako, M.Hikita, M.Sato, H.Abe, M.Hirokawa, H.Sato

The 2020 International Conference on Condition Monitoring and Diagnosis (CMD2020) ( 458 ) 2020年10月

Digest Report of Cooperative Research Committee on EINA Magazine Publication 査読有り

M.Nagao, Y.Inoue, M.Kozako, N.Fuse

2020 International Symposium on Electrical Insulating Materials (ISEIM) ( DR-8 ) 2020年09月

Digest Report of Investigating R&D Committee on Electrical Insulation Reliability of Power Modules 査読有り

M.Kozako, N.Kishi, Y.Hayase

2020 International Symposium on Electrical Insulating Materials (ISEIM) ( DR-4 ) 2020年09月

Dielectric Breakdown Characteristic of Refining Treatment Fullerene Doped Epoxy Plate-like Specimens 査読有り

K.Agung Satria, K.Ozuno, Y.Inoue, M.Kozako, M.Hikita, Suwarno, U.Khayam, T.Igarashi, H.Kaji

2020 International Symposium on Electrical Insulating Materials (ISEIM) ( VF-5 ) 2020年09月

Discharge Inception Characteristics Analysis of Epoxy/Silica Nanocomposites in SF6 Gas Using Volume-time Theory 査読有り

Y.Inoue, K.Ohzuno, M.Kozako, M.Hikita, H.Masui, H.Mitsudome, H.Yanase, K.Okamoto

2020 International Symposium on Electrical Insulating Materials (ISEIM) ( VL-7 ) 2020年09月

Examination of Impulse PD Inception Location by Electric Field Analysis in Ester Oil/Pressboard Composite Insulation System 査読有り

T.Yamada, M.Kozako, M.Hikita, S.Yoshida, H.Hamada, T.Umemoto

2020 International Symposium on Electrical Insulating Materials (ISEIM) ( VL-6 ) 2020年09月

Optimization of Partial Discharge Detection Sensitivity of Transient Earth Voltage Sensors Using FDTD Modeling 査読有り

S.Hari Wibowo, U.Khayam, Suwarno, Y.Kakimoto, M.Kozako, M.Hikita

2020 International Symposium on Electrical Insulating Materials (ISEIM) ( VJ-8 ) 2020年09月

Proposal of Noise Rejection in Automatic Measurement System of Repetitive Partial Discharge Inception Voltage 査読有り

Y.Nishigaki, S.Takenouchi, M.Kozako, M.Hikita, T.Nakamura, J.Sun, A.Izumi, T.Sakurai, K.Karasawa,T.Hirose

2020 International Symposium on Electrical Insulating Materials (ISEIM) ( VJ-7 ) 2020年09月

九州支部における最近の活動状況査読有り

小迫雅裕

電気学会誌 ( 一般社団法人電気学会 ) 140 ( 8 ) 551 - 551 2020年08月

担当区分：筆頭著者記述言語：日本語掲載種別：記事・総説・解説・論説等（学術雑誌）

大会概要第72回電気・情報関係学会九州支部連合大会が2019年9月27日（金）・28日（土）の二日間にわたり天気に恵まれる中，九州工業大学・戸畑キャンパスで開催された。本大

DOI： 10.1541/ieejjournal.140.551

CiNii Article

CiNii Research

その他リンク： https://www.jstage.jst.go.jp/article/ieejjournal/140/8/140_551/_pdf

V-t Characteristics of Twisted-pair with Polyvinyle Formal Wires Undergoing Thermal Stress in Mineral Oil 査読有り

M.Hikita, Y.Nishigaki, S.Takenouchi, T.Matsuzoe, M.Kozako, K.Shimomura, S.Kawakami, T.Tanaka

2020 International Conference on Dielectrics (ICD) 130 - 133 2020年07月

Impulse Flashover Characteristics in SF Gas for Insulating Spacer Model of GIS Fabricated Using Nano-micro Composites 査読有り

Y.Inoue, K.Abe, K.Ohzuno, M.Kozako, M.Hikita, H.Masui, H.Mitsudome, H.Yanase, K.Okamoto

2020 International Conference on Dielectrics (ICD) 810 - 813 2020年07月

Comparison of the Effect of Thermal Aging on Dielectric Properties of Vegetable Oils and Impregnated Kraft Paper 査読有り

C.Méndez Gutiérrez, H.Araki, T.Yamada, M.Tsuchie, M.Kozako, M.Hikita, A.Ortiz Fernández

2020 International Conference on Dielectrics (ICD) 732 - 735 2020年07月

Field Grading Material electrodeposition - challenges 査読有り

G.Belijar, L.Fetouhi, M.Kozako, M.Hikita

2020 International Conference on Dielectrics (ICD) 289 - 292 2020年07月

Partial Discharge Properties till Breakdown of Boehmite Added Enameled Twisted Pair under Bipolar Repetitive Impulse Voltage Application 査読有り国際誌

S.Takenouchi, Y.Nishigaki,T.Matsuzoe, M.Kozako, M.Hikita, N.Fujimoto, N.Hayashizaka, T.Kato, H.Kikuchi

2020 Electrical Insulation Conference (EIC) ( 2286 ) 2020年06月

High Temperature Partial Discharge Inception Voltage under Repetitive Impulse Voltage Applied to Motorette Samples 査読有り国際誌

Y.Nishigaki, T.Matsuzoe, S.Takenouchi, M.Kozako, M.Hikita, T.Nakamura, S.Jintong, A.Izumi, T.Sakurai, K.Karasawa, S.Hiroshima

2020 Electrical Insulation Conference (EIC) ( 2287 ) 2020年06月

前課電による空間電荷蓄積が部分放電開始電圧へ与える影響査読有り

美馬まいみ, 成田迅宏, 三宅弘晃, 田中康寛, 小迫雅裕, 匹田政幸

電気学会論文誌A 140 ( 5 ) 276 - 284 2020年05月

電力線搬送通信を用いた新しいオンライン部分放電監視システムの構築査読有り

吉川雛, 柿本康朝, 小迫雅裕, 匹田政幸, 里秀文, 田頭秀樹, 副田正裕

電気学会論文誌A 140 ( 4 ) 261 - 262 2020年04月

炭化水素系熱硬化性樹脂の電気絶縁特性に及ぼすフラーレン添加の影響査読有り

大角浩太郎, 阿部和馬, 小迫雅裕, 匹田政幸, 亀井伸人

電気学会論文誌A 140 ( 4 ) 241 - 246 2020年04月

Electrical characteristics of double-sided cooling SiC power module using Ni micro plating bonding 査読有り

T.Itose, A.Kawagoe, A.Imakiire, M.Kozako, M.Hikita, K.Tatsumi, T.Iizuka, I.Morisako, N.Sato, K.Shimizu, K.Ueda, K.Sugiura, K.Tsuruta

11th International Conference on Integrated Power Electronics Systems(CIPS) 422 - 427 2020年03月

モールド変圧器におけるUHF法および照射X線走査を用いた新規部分放電位置標定査読有り

匹田政幸, 飯田和生, 梅村時博, 中村勇介, 中前哲夫, 前田照彦, 東山雅一

電気学会論文誌A 140 ( 3 ) 162 - 168 2020年03月

Construction of Novel Online Partial Discharge Monitoring System in Model Power Apparatus Using Power Line Communication 査読有り国際誌

H.Yoshikawa, S.Masuda, Y.Kakimoto, N.Puspitasari, Y.Nakano, M.Kozako, M.Hikita, H.Sato, H.Tagashira, K.Ishida

Proceedings of the 21st International Symposium on High Voltage Engineering 1 635 - 642 2019年11月

Diagnostics For Vacuum Degree Of Vacuum Interrupter Based On Partial Discharge Mechanisms Under Medium Vacuum Level 査読有り国際誌

Y.Nakano, M.Kozako, M.Hikita, T,Tanaka, M.Kobayashi

Proceedings of the 21st International Symposium on High Voltage Engineering 1 673 - 683 2019年11月

Propagation Characteristics of Partial Discharge Radiated Electromagnetic Waves for Insulation Diagnosis of Oil-Filled Bushing 査読有り国際誌

T.Fujimura, S.Masuda, M.Kozako, M.Hikita, T.Yamamoto, S.Okabe, M.Nakahata

Proceedings of the 21st International Symposium on High Voltage Engineering 1 662 - 672 2019年11月

Partial Discharge Measurement and Its High Frequency Characteristics in Cast Resin Transformer 査読有り国際誌

T.Fujimura, S.Masuda, M.Kozako, M.Hikita, T.Umemura, K.Iida, Y.Nakamura, T.Nakamae, T.Maeda, M.Higashiyama

Proceedings of the 21st International Symposium on High Voltage Engineering 1 653 - 661 2019年11月

Identification Of Partial Discharge Source In Power Apparatus In Practical Substation Utilizing Artificial Neural Network 査読有り国際誌

Y.Kakimoto, P.Nuraida, H.Yoshikawa, T.Fujimura, M.Kozako, M.Hikita, O.Eda, Y.Shiina, M.Otsuka, H.Kaneko

Proceedings of the 21st International Symposium on High Voltage Engineering 1 643 - 652 2019年11月

Discharge characteristics and mechanisms under the medium vacuum region in a vacuum interrupter 査読有り

Nakano Y., Masuda S., Kozako M., Hikita M., Tanaka T., Kobayashi M.

IEEJ Transactions on Electrical and Electronic Engineering 14 ( 11 ) e1 - e6 2019年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. This article deals with discharge characteristics and mechanisms in the medium vacuum range of 1–1000 Pa in a vacuum interrupter (VI), which consists of complex electrode configuration with an electrode of floating potential and an insulator. Gas leakage was simulated by enclosing air or SF6 gas. From a measured discharge current and a shield potential, the discharge characteristics inside the VI at each pressure were discussed. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

DOI： 10.1002/tee.23019

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Investigation for influence of space charge accumulation in motor winding coating material on partial discharge inception voltage 査読有り

T.Narita, M.Mima, H.Miyake, Y.Tanaka, M.Kozako, M.Hikita

2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( 6D-2 ) 718 - 721 2019年10月

Estimation of Electron Trap in Hydrocarbon-Based Thermosetting Resin/Fullerene Composite by Computational Science 査読有り

K.Ohzuno, K.Abe, M.Kozako, M.Hikita, N.Kamei

2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( 8-2 ) 839 - 842 2019年10月

Partial Discharge Inception Voltage Characteristics for Nano-micro Composites under Impulse Voltage in SF6 Gas 査読有り

K.Abe, K.Ohzuno, M.Kozako, M.Hikita, H.Mitsudome, H,Yanase, K.Okamoto

2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena(CEIDP) ( 6D-7 ) 738 - 741 2019年10月

DetectingVacuum Degree Condition of Vacuum Interrupter by Partial Discharge Measurement 査読有り

A.S.Habibie, M.Hikita, M.Kozako, Y. Nakano, Suwarno, U. Khayam, M.Kobayashi

5th International Conference on Electric Power Equipment -Switching Technology(ICEPE-ST 2019) ( C-4-1 ) 193 - 196 2019年10月

Niメッキ接合を用いたSiCパワーモジュールの熱抵抗と過渡熱解析査読有り

今給黎明大, 小迫雅裕, 匹田政幸, 巽宏平, 稲垣雅一, 飯塚智徳, 佐藤信明, 清水孝司, 上田和敏, 杉浦和彦, 鶴田和弘, 戸田敬二

電気学会論文誌D 139 ( 10 ) 838 - 846 2019年10月

Estimation method of degraded vacuum in vacuum interrupter based on partial discharge measurement 査読有り

Nakano Y., Kozako M., Hikita M., Tanaka T., Kobayashi M.

IEEE Transactions on Dielectrics and Electrical Insulation 26 ( 5 ) 1520 - 1526 2019年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 1994-2012 IEEE. Loss of vacuum in vacuum interrupter (VI) is becoming an interesting theme for VI used in medium voltage range beyond its lifetime of typically 20-30 years. The early detection of abnormality in the vacuum insulated equipment is important not only for the operating vacuum circuit breakers (VCBs) in medium voltage but also for the development of higher voltage VCBs, such as cubicle type gas insulated switchgear (C-GIS) with compressed gas and/or insulation gas. The purpose of present study is to estimate the vacuum degree in VI by measuring partial discharges (PDs) occurring in medium vacuum range for more than 1 Pa. As a leakage gas, atmospheric air and SF6 gas were sealed into the VI with close-state, whose pressure was regulated through vacuum pump systems, which corresponds to the left region of its PD inception voltage (PDIV) curve. From PD current waveforms measured by detecting resistor connected to plane electrode outside the VI, PD charges, occurrence frequency and phase characteristics of PDs for each applied AC voltage and internal vacuum pressure were determined. It was concluded that, by statistical processing using PD parameters and histogram, a number of occurrence of PD and PD charges would be dominant parameter for determination of the internal pressure of VI with the leakage gas of air.

DOI： 10.1109/TDEI.2019.008142

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Partial Discharge Waveform Identification using Image with Convolutional Neural Network 査読有り国際誌

Puspitasari N., Khayam U., Suwarno , Kakimoto Y., Yoshikawa H., Kozako M., Hikita M.

2019 54th International Universities Power Engineering Conference, UPEC 2019 - Proceedings 2019年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Romania Bucharest 2019年09月03日 - 2019年09月06日

© 2019 IEEE. The use of Neural Network as a tool for Partial Discharge (PD) Identification has been used since the 1990s, where Backpropagation Neural Network (BPNN) with input in the form of data values was the most widely used method. However, for the past five years, Convolutional Neural Network (CNN) has been used to identify Partial Discharge with input in the form of images. Pattern Recognition of Partial Discharge Image Based on One-dimensional Convolutional Neural reported by Wan et al. in CMD 2018 was using images of 5 cycles repeated waveform pattern images as input. In our research, we used two-dimensional images of time domain single PD waveform obtained from experiments using three sensors (High-Frequency Current Transformer (HFCT), Surface Current Sensor (SCS), and Transient Earth Voltage (TEV) sensor) for input to CNN. The images were extracted using Gaussian Filter on the Convolutional layer, then searched the maximum value for each group of pixels to make computing easier on the Pooling Layer, and finally identified on the Fully Connected Layer. The purpose of this study is to develop a PD diagnostic technique that could simplify the identification of PD sources by using a signal waveform image for identification. The experimental results show that the proposed method has sufficient accuracy in identifying Partial Discharge, and it may be possible to identify Partial Discharge in HV voltage equipment by comparing field data.

DOI： 10.1109/UPEC.2019.8893577

Scopus

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Construction of Novel Online Partial Discharge Monitoring System in Model Power Apparatus using Power Line Communication 査読有り

H.Yoshikawa, S.Masuda, Y.Kakimoto, N.Puspitasari, Y.Nakano, M.Kozako, M.Hikita, H.Sato, H.Tagashira, K.Ishida

The 21th International Symposium on High Voltage Engineering(ISH2019) ( 853 ) 1 - 8 2019年08月

Numerical Simulation For Creepage Discharge In Oil/Pressboard Composite Insulation System With Multiple Pressboards 査読有り

S.Yoshida, T.Yamada, Y.Nakano, M.Kozako, M.Hikita

The 21th International Symposium on High Voltage Engineering(ISH2019) ( 1096 ) 2019年08月

Diagnostics For Vacuum Degree Of Vacuum Interrupter Based On Partial Discharge Mechanisms Under Medium Vacuum Level 査読有り

Y.Nakano, M.Kozako, M.Hikita, T,Tanaka, M.Kobayashi

The 21th International Symposium on High Voltage Engineering(ISH2019) ( 887 ) 1 - 11 2019年08月

Propagation Characteristics of Partial Discharge Radiated Electromagnetic Waves for Insulation Diagnosis of Oil-Filled Bushing 査読有り

T.Fujimura, S.Masuda, M.Kozako, M.Hikita, T.Yamamoto, S.Okabe, M.Nakahata

The 21th International Symposium on High Voltage Engineering(ISH2019) ( 881 ) 1 - 10 2019年08月

Partial Discharge Measurement and Its High Frequency Characteristics in Cast Resin Transformer 査読有り

T.Fujimura, S.Masuda, M.Kozako, M.Hikita, T.Umemura, K.Iida, Y.Nakamura, T.Nakamae, T.Maeda, M.Higashiyama

The 21th International Symposium on High Voltage Engineering(ISH2019) ( 872 ) 1 - 8 2019年08月

Identification Of Partial Discharge Source In Power Apparatus In Practical Substation Utilizing Artificial Neural Network 査読有り

Y.Kakimoto, P.Nuraida, H.Yoshikawa, T.Fujimura, M.Kozako, M.Hikita, O.Eda, Y.Shiina, M.Otsuka, H.Kaneko

The 21th International Symposium on High Voltage Engineering(ISH2019) ( 869 ) 1 - 11 2019年08月

Effect of lightning impulse prestress on AC partial discharge characteristics in cast resin transformer 査読有り

Maruyama H., Matsuo K., Kozako M., Hikita M., Iida K., Umemura T., Nakamura Y., Nakamae T., Maeda T., Higashiyama M.

Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) 208 ( 1-2 ) 10 - 16 2019年07月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Wiley Periodicals, Inc. It is crucial for cast resin transformer to detect void and delamination existing in the cast resin because these defects reduce insulation performance of cast resin equipment. Furthermore, defects are likely to be mixed in cast resin because of several surface boundaries between resin and conductor. It is considered that detecting partial discharge (PD) is effective to diagnose equipment of power equipment. However, it is reported that withstand lightning impulse voltage test may give influence on AC partial discharge test, especially partial discharge inception voltage. This paper deals with accumulated charge in a void under AC voltage to investigate the effect of the impulse voltage prestress on subsequent AC PD characteristics in cast resin transformer. AC PD characteristics were compared before and after impulse application. In addition, recovery of PD characteristics was measured to investigate charge decay. As a result, the mechanism of prestress effect is revealed and surface charge density is estimated quantitatively in cast resin transformer.

DOI： 10.1002/eej.23177

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Discharge characteristics with impulse voltage application in ester oil/pressboard composite 査読有り

T.Yamada, Y.Nakano, M.Kozako, M.Hikita, S.Yoshida, S.Kainaga, M.Yoshimura, K.Suga

IEEE International Conference on Dielectric Liquids (ICDL2019) ( 1198 ) 2019年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Italy Roma 2019年06月23日 - 2019年06月27日

© 2019 IEEE. Partial discharge characteristics as well as breakdown phenomena in a power transformer insulation, i.e. oil and paper insulation, has to be clarified for miniaturization of the apparatus. In recent years, environmental-friendly transformers using ester oil, which shows excellent biodegradability, receive much attention due to the worldwide growing environmental awareness. Considering this, researches on fundamental characteristics of discharge phenomena within the ester oil are required. Although various papers on discharge characteristics in the ester oil have been published by many researchers, there are still few reports on these researches using ester oil and pressboard (PB) composite insulation system. In this paper, the discharge inception field and starting point in the ester oil and PB composite insulation configuration are investigated and the results are compared with those in the mineral oil to discuss the detailed discharge mechanisms.

DOI： 10.1109/ICDL.2019.8796623

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Temperature Dependence of RPDIV of Motorette Sample with Varnish Treatment 査読有り

Y.Nishigaki, T.Matsuzoe , T.Kubo, Y.Nakano, M.Kozako, M.Hikita, T.Nakamura, J.Sun, A.Izumi, T.Sakurai K.Karasawa, K.Nojima

2019 Electrical Insulation Conference (EIC) ( P-1-5 ) 18 - 21 2019年06月

Dielectric and Insulation Propertiesof Polyimide-based Boehmite Nanocomposite Material 査読有り

T.Matsuzoe, N.Kita, Y.Nishigaki,T. Abe, T.Kubo, Y.Nakano, M.Kozako, M.Hikita, N.Fujimoto, N.Hayashizaka, S.Fujimoto, T.Kato

2019 Electrical Insulation Conference (EIC) ( P-3-1 ) 83 - 86 2019年06月

Partial discharge detection method for vacuum leakage diagnosis of a vacuum interrupter 査読有り

Y.Nakano, M.Kozako, M.Hikita, T.Tanaka, M.Kobayashi

IEEJ Transactions on Electrical and Electronic Engineering 14 ( 6 ) 819 - 824 2019年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. Vacuum circuit breakers (VCBs) have been widely used in the medium distribution voltage range of 12–38 kV for more than half a century. Recent interest for them is because of the loss of vacuum in a vacuum interrupter (VI). Generally, the leakage is an improbable event during the expected lifetime of typically 20–30 years, while there are some reports that VIs beyond their expected lifetime have a significantly higher leakage rate. To keep the high reliability of middle voltage VCB, even for the high voltage VCB, it is necessary to develop the earlier detection method of vacuum leakage from VI. In the present study, an experimental setup with a partial discharge (PD) detecting system for detecting vacuum leakage from a test VI was constructed. The internal pressure of VI was arbitrarily regulated in the range of 0.02–100 Pa through an insulating tube using several valves. A detecting resistor of 1 kΩ was connected to a plane electrode located outside 115 mm away from VI to measure the PD current due to discharges inside the VI. A current transformer (CT) was also placed below the plane electrode. Sensors with different specification for PD detection, such as a transient earth voltage sensor, a horn antenna, and an acoustic emission sensor, were investigated and characterized. As a result of pressure dependence of PD inception voltage, it follows the left side of Paschen's Law in the pressure range more than 2.0 Pa, while no discharges occurred below 2.0 Pa. To analyze the PD charge and rise time from measured waveforms, the PD mechanism in the medium voltage range inside the VI was discussed. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

DOI： 10.1002/tee.22870

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開閉インパルス電圧繰返し重畳と油隙内部の状態が油浸紙-絶縁油複合絶縁系の部分放電特性に与える影響査読有り

吉積弘将, 小迫雅裕, 匹田政幸, 藤井祐樹, 中村勇介, 長広明

電気学会論文誌B 139 ( 6 ) 446 - 454 2019年06月

Development and evaluation of SiC inverter using Ni micro plating bonding power module 査読有り

A.Kawagoe, T.Itose, A.Imakiire, M.Kozako, M.Hikita, K.Tatsumi, T.Iizuka, I.Morisako, N.Sato, K.Shimizu, K.Ueda, K.Sugiura, K.Tsuruta, K.Toda

2019 IEEE International Workshop on Integrated Power Packaging, IWIPP 2019 36 - 39 2019年04月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

France Toulouse 2019年04月24日 - 2019年04月26日

© 2019 IEEE. This paper reports on evaluation of inverter system using silicon carbide (SiC) power module with a novel packaging technology of Ni micro plating bonding. The power module is developed to make the structure maximize the performance of SiC attracting attention in recent years. As a result, it was found that the developed inverter reduces the inverter loss and improves the efficiency of the entire inverter system as compared with in-vehicle product using Si-IGBT and the inverter consisting of the conventional package structure using SiC MOSFET. Moreover, it was confirmed that switching was possible even when the chip temperature exceeded 200°C, suggesting that the developed inverter can be driven under the high temperature environment.

DOI： 10.1109/IWIPP.2019.8799079

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Drastic Change in Non-Linear Resistive Materials I(V) Characteristics 査読有り

Belijar G., Hermette L., Kozako M., Hikita M.

2019 IEEE International Workshop on Integrated Power Packaging, IWIPP 2019 97 - 101 2019年04月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

France Toulouse 2019年04月24日 - 2019年04月26日

© 2019 IEEE. Non-linear Resistive Materials are thought to be able to solve aging issues due to intense electric field near triple junction in DBC/AMB substrate of power module. In present study, non-linear I(V) behavior of epoxy/ZnO microvaristor is characterized. Large change in the I(V) characteristic is observed during successive measurements, meaning that material degradation occurred. Optical microscopy of the material surface gave an insight of the phenomenon leading those modifications, an hypothesis on the degradation mechanism is proposed.

DOI： 10.1109/IWIPP.2019.8799097

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Construction and verification of novel insulation defect location system with high space resolution for next generation power module 査読有り

Maki J., Matsuzoe T., Kozako M., Hikita M., Nakamura Y., Taniguchi K., Ikeda Y., Okamoto K.

2019 International Conference on Electronics Packaging, ICEP 2019 325 - 328 2019年04月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Niigata 2019年04月17日 - 2019年04月19日

© 2019 Japan Institute of Electronics Packaging. This paper reports on construction and verification of a high space resolution partial discharge (PD) location system for the next generation power module. A novel PD location method (polarity reversion method) is proposed by calculating electromagnetic wave (EMW) propagation characteristics inside the power module using finite difference time domain (FDTD) analysis. In addition, EMW signal characteristics under AC voltage and impulse voltage application are compared. Based on these results, an automatic PD location system has been successfully constructed under the impulse voltage application.

DOI： 10.23919/ICEP.2019.8733578

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High temperature dielectric property of silicon nitride insulating substrate for next generation power module up to 350 degrees Celsius. 査読有り

Abe T., Nishigaki Y., Kozako M., Hikita M.

2019 International Conference on Electronics Packaging (ICEP2019) 444 - 448 2019年04月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Niigata 2019年04月17日 - 2019年04月19日

© 2019 Japan Institute of Electronics Packaging. Recently, as power module tends to have higher output density, large-capacity and downsizing of the module are demanded. It also tends to operate at higher temperatures. From the above circumstances, evaluation of high temperature electrical properties of ceramic insulating substrates for application of next generation power module becomes important. However, there are very few reports on the high temperature insulation property of the ceramic insulating substrate. This paper presents dielectric properties (relative permittivity ϵr, relative dielectric loss factor ϵr″ and AC conductivity σac) of ceramic insulating substrate consisting of Silicon Nitride (Si3N4) used for next generation power module up to high temperature of 350 °C. Besides, DC conductivity σdc are evaluated as a function of the temperature of the substrate, from which the activation energy Ea was calculated. Thus obtained results are discussed with the temperature dependence of the permittivity and ac conductivity considered. An attempt is also made to evaluate specific properties of the Si3N4 substrate by comparing with the dielectric properties of Aluminum Nitride (A1N) substrate.

DOI： 10.23919/ICEP.2019.8733529

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過渡接地電圧法による部分放電信号の低周波成分伝搬メカニズムの考察査読有り

吉積弘将, 小迫雅裕, 匹田政幸, 藤井祐樹, 中村勇介, 長広明

電気学会論文誌A 139 ( 3 ) 154 - 160 2019年03月

マイクロ発泡皮膜電線の部分放電開始電圧に及ぼす巻付け時の機械的ストレスの影響査読有り

久保智洋, 前田健太, 小迫雅裕, 匹田政幸, 福田秀雄, 池田佳祐, 冨澤恵一, 武藤大介

電気学会論文誌A 139 ( 3 ) 161 - 166 2019年03月

Volume-Time理論を用いた発泡皮膜線ツイストペアのインパルス部分放電開始電圧の推定査読有り

前田健太, 久保智洋, 小迫雅裕, 匹田政幸, 福田秀雄, 池田佳祐, 冨澤恵一, 武藤大介

電気学会論文誌A 139 ( 3 ) 167 - 173 2019年03月

研究調査委員会レポート：パワーモジュールの電気絶縁信頼性に関する調査専門委員会査読有り

小迫雅裕, 早瀬悠二, 岸直哉

電気学会論文誌．　Ａ ( 一般社団法人電気学会 ) 139 ( 9 ) NL9_4 - NL9_4 2019年01月

Study on static electrification of the PFAE-mineral oil mixture 査読有り

Rajab A., Gumilang H., Tsuchie M., Kozako M., Hikita M., Suzuki T.

IOP Conference Series: Materials Science and Engineering 602 ( 1 ) 2018年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Indonesia Padang, 2018年11月08日 - 2018年11月09日

© 2019 IOP Publishing Ltd. The natural ester of tri-ester type has been implemented on a high voltage large power transformer, rated at 420 kV, since 2014. The high voltage transformer is known prone to the static electrification risk. Palm fatty acid ester (PFAE) which is a monoester oil type has also been tried on the high voltage power transformer. For a retrofilling purpose, some portion of the previously used insulating oil (it is mainly mineral oil) will remain in the transformer. It is then demanded to study the static electrification of a mixture of PFAE and mineral oil. This paper presents an investigation results on the static electrification properties of PFAE-mineral oil mixture at various percentage ratios of PFAE. The results show that charging tendency (ECT) increase with the percentage ratio of PFAE, but then decreases for the oil containing only PFAE. On the other side, the resistivity of oil mixtures decreases with the increase of percentage ratio of PFAE but then increases for the oil containing only PFAE.

DOI： 10.1088/1757-899X/602/1/012016

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Discharge Characteristics and Mechanisms under Medium Vacuum Region in Vacuum Interrupter 査読有り

Y.Nakano, S.Masuda, M.Kozako, M.Hikita, T.Tanaka, M.Kobayashi

The 11th International Workshop on High Voltage engineering (IWHV2018) ( ED-18-092 SP-18-044 HV-18-126 ) 2018年11月

Electric Field Relaxation Effect of Micro-varistor/epoxy Composite 査読有り

K.Abe, S.Harada, Y.Nakano, M.Kozako, M.Hikita, T.Yamamoto, S.Okabe

Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) 2018-October 167 - 170 2018年10月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Mexico Cancun 2018年10月21日 - 2018年10月24日

© 2018 IEEE. To reduce the size of electric power equipment and enhance its reliability, the electric field stress around spacer in gas insulated switchgear (GIS) should be considered. For the electric field relaxation to such a solid insulation system, a non-linear resistive material (NRM) seems effective. NRM is a composite of micro-varistor and epoxy, and it has excellent non-linear V-I characteristic. This paper deals with verification of the effect of NRM on the field relaxation using a model simulating epoxy spacer with NRM in comparison with metal embedded spacer. By embedding NRM under the electrode, the electric field of the triple junction (TJ) composed of the electrode, gas and insulator can be relaxed by 72 % under the impulse voltage (10 kV). In addition, it can also reduce the electric field concentration by 73 % at the embedded tip in AC voltage.

DOI： 10.1109/CEIDP.2018.8544813

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Evaluation of Dielectric Strength of Tricyclopentadiene / Silica Microcomposites 査読有り

Y.Ookubo, M.Kozako, M.Hikita, N.Kamei

The 2018 Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) 2018-October 594 - 597 2018年10月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Mexico Cancun 2018年10月21日 - 2018年10月24日

© 2018 IEEE. Hydrocarbon-based thermosetting resins have properties such as low viscosity, low dielectric constant and high heat resistance as compared with epoxy resins and are expected to be applied to electric devices in the future. However, hydrocarbon-based thermosetting resins have not been put into practice as an electrically insulating material yet. Therefore, it is necessary to understand the electrical characteristics. Generally, when organic polymeric material is used as an insulator for high voltage equipment, a large amount of loading of inorganic fillers is needed so as to decrease linear expansion coefficient. Therefore, it is crucial to investigate the effect of inorganic filler loading on the various properties such as mechanical, thermal, and electrical properties for higher voltage and longer term operation of highvoltage equipment. From the viewpoints, this paper deals with electrical insulation properties of the hydrocarbon-based thermosetting resin with loaded micro silica particles. As a result, breakdown strength of hydrocarbon-based thermosetting resin is equal or higher than that of the epoxy resin. As a result, it can be said that the hydrocarbon-based thermosetting resin with lower viscosity and lower dielectric constant than the epoxy resin is promising as an insulating material for the next generation high voltage equipment.

DOI： 10.1109/CEIDP.2018.8544821

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Basic Study on Partial Discharge Detection with High Sensitivity using Ferrite Core 査読有り

H.Yoshikawa, S.Masuda, Y.Nakano, M.Kozako, M.Hikita, T.Mawatari, T.Matsumoto

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P62 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

© 2018 IEEE. Recently, deterioration of insulation in power equipment such as power cables due to partial discharge (PD) can give rise to crucial accident in power systems. To prevent serious failures in power equipment, on-site monitoring and early PD detection is important. In the present study, a new PD detection method using ferrite core (FC), which is inexpensive and easy to install, is proposed. FC is generally used to remove high frequency noises using its resistance component increasing with the frequency. As basic study on PD detection with various kinds of FCs, the frequency dependence of impedance was investigated. As a result, FC was found to provide much higher PD detection sensitivity than a high frequency current transformer (HFCT). The number of FC installed and its type were also found to give a great influence on the sensitivity and frequency band in PD detection. In conclusion, it was shown that FC is applicable for PD detection in power equipment.

DOI： 10.1109/CMD.2018.8535822

Scopus

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Design and Fabrication of 3-D Cube UHF Antenna for Partial Discharge Detection 査読有り

A.Fauzan, U.Khayam, Suwarno, M.Kozako, M.Hikita

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P68 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

Simulation of Electromagnetic Wave and Surface Current Caused by PD for Seeking Better Detection Sensitivity by TEV Sensor Attached with a Bucket 査読有り

A.Fauzan, U.Khayam, Suwarno, H.Yoshizumi, M.Kozako, M.Hikita

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P12 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

© 2018 IEEE. Partial discharge (PD) is one of electrical phenomena which might occur in high voltage (HV) cable joint. Many methods have been tried to detect PD for cable joints installed in a manhole. Among them, an attempt is made to detect PD by transient earth voltage (TEV) sensor attached inside a metal bucket which is brought down into the manhole. This PD detection method can be used to diagnose the cable joint condition and to ensure safety of the personnel before entering the manhole. This paper presents simulation of electromagnetic wave emitted by PD and induced surface current flowing on the surface of the metal bucket to enhance the PD detection sensitivity. The simulation was made with a three-dimension finite difference time domain (FDTD) simulation software (CTC Co.; MAGNA TDM version 8.3) by changing the bucket depth, diameter, aperture angle and material, as well as excitation frequency of PD source and distance from the bucket. As a result, it was found that an optimal metal bucket shape providing the highest detection sensitivity in terms of the surface current is bucket with 0° aperture angle (cylindrical shape), outer diameter 300 mm, bucket depth 150 mm for iron material with 1mm in thickness under the circumstances of the manhole in which the cable joints are installed.

DOI： 10.1109/CMD.2018.8535615

Scopus

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Partial Discharge Location in Cast Resin Transformer by Multiple Small Loop Sensors 査読有り

T.Fujimura, S.Masuda, Y.Nakano, Μ.Kozako, Μ.Hikita, Y.Nakamura, K.Iida, T.Umemura, T.Maeda, M.Higashiyama

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P64 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

© 2018 IEEE. In epoxy cast resin power apparatus, there exist unexpected insulation defects of voids and delamination. Existence of such defects can generate partial discharge (PD) with degradation of the epoxy, which eventually leads to electrical breakdown with crucial damage to the insulation systems. Thus, early PD detection and specifying the location for such defects is important. This study presents PD location in epoxy cast resin transformer of rated voltage of 6.6 kV by detecting electromagnetic (EM) wave emitted by PD using several small loop sensors. As a result, it was found that the signal intensity and arrival time difference of EM wave detected with two loop sensors can confine the defect area. Furthermore, the arrival order of EM waveforms by sensor position was measured using arrayed four loop sensors, which can locate PD in more detail. Other experimental results on PD location using X-ray irradiation to the cast resin transformer including voids was found to correspond to that provided by the present four loop sensors' PD location method. In addition, the advantage of defect location of LS was confirmed by comparison with other sensors.

DOI： 10.1109/CMD.2018.8535916

Scopus

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Estimation of Internal Pressure of Vacuum Interrupter by Measuring Partial Discharge Current 査読有り

Y.Nakano, S.Masuda, M.Kozako, M.Hikita, T.Tanaka, M.Kobayashi

28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV2018) 2 611 - 614 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Germany Greifswald 2018年09月23日 - 2018年09月28日

© 2018 IEEE. Loss of vacuum in vacuum interrupter (VI) is becoming an interesting theme for VI used in medium voltage range beyond its lifetime of typically 20-30 years. The early detection of abnormality in the vacuum insulated equipment must be important for the development of higher voltage vacuum circuit breakers (VCBs), such as cubicle type gas insulated switchgear (C-GIS) with compressed gas and/or insulation gas. In the present study, for the purpose of diagnosing the vacuum pressure in VI by a partial discharge (PD) measurement, PD characteristics in medium vacuum range of 1 Pa to 100 Pa were investigated. As a leakage gas, air was sealed into the VI, and its pressure was regulated from 2.2 Pa to 100 Pa, which corresponds to the left region of Paschen curve. From PD current waveforms by detecting resistor connected to plane electrode outside the VI, the charges, occurrence frequency and phase characteristics of PDs for each applied AC voltage and internal vacuum pressure were determined. It was concluded that a number of occurrence of PD and PD charges would be dominant parameter for determination of the internal pressure of VI.

DOI： 10.1109/DEIV.2018.8537045

Scopus

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Discussion on Partial Discharge Measurement Technique of Cable Joint in Three Phase High Voltage Overhead Transmission Line 査読有り

S.Masuda, T.Fujimura, Y.Nakano, M.Kozako, M.Hikita, H.Haruyama, K.Miyazaki, H.Sat, F.Aono

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P61 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

© 2018 IEEE. Cable joint in high voltage overhead transmission line connecting a pole transformer is one of the important accessories. Reliable diagnostic technique for possible insulation failures in cable joint due to the long-term operation and aging is required. The purpose of this research is to establish the insulation diagnostic technique for the cable joint by measuring partial discharge (PD), which is a precursor phenomenon of dielectric breakdown. In this paper, PD signals in three-phase high voltage overhead transmission lines with 6.6 kV cable joints, actually used in electric power company, were measured by using various sensors, i.e., high frequency current transformer (HFCT), monopole antenna, and transient earth voltage (TEV) sensor. As a result, it is shown that HFCT shows the highest sensitivity for PD detection among three kinds of sensors. It is also shown that the arrival time difference of the PD signals detected by several HFCTs enables to determine the PD source in neighboring two utility poles. Furthermore, the intensity and the polarity of first arrival part of the PD signals detected by several HFCTs enable to determine the PD source in a particular cable joint among the three ones in a utility pole.

DOI： 10.1109/CMD.2018.8535875

Scopus

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Determination of Type of Partial Discharge in Cubicle-Type Gas Insulated Switchgear (C-GIS) using Artificial Neural Network 査読有り

T.R.Sukma, U.Khayam, Suwarno, R.Sugawara, H.Yoshikawa, M.Kozako, M.Hikita, O.Eda, M.Otsuka, H.Kaneko, Y.Shiina

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P10 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

© 2018 IEEE. Partial discharge (PD) measurement is performed as one of diagnostic tool for condition monitoring in cubicle-type gas insulated switchgear (C-GIS). This paper presents artificial neural network (ANN) to identify the type of PD occurring in C-GIS. PD measurement results obtained from C-GIS in a field were fed to the ANN as input parameters to determine the type of PD or external noises. The C-GIS consists of two compartments of power cables and two compartments of transformers. PD measurements were conducted in the C-GIS using a commercial PD measurement system consisting of an oscilloscope and three different kinds of sensors (transient earth voltage sensor, surface current sensor and high frequency current transformer) to generate input signal waveform parameters for ANN (field data). An attempt was made to locate the PD source using the output of the sensors set at different sites. PD measurements using four kinds of artificial PD sources were also conducted in laboratory using the same PD measurement system to obtain another signal waveform parameters (laboratory data) which were used for training the ANN. Thereafter, an attempt was also made to identify PD source occurring in C-GIS using field data as input for the trained ANN. As a result, the developed ANN was found to predict the kind of PD source as void-discharge with 99% probability.

DOI： 10.1109/CMD.2018.8535657

Scopus

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Determination of Partial Discharge Location in Stator Core using Loop Sensors 査読有り

J.Maki, T.Kubo, T.Matsuzoe, Y.Nakano, M.Kozako, M.Hikita, T.Ueno, J.Sun, A.Izumi, K.Karasawa

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P175 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

© 2018 IEEE. Inverter drive motors with higher voltage, higher-speed switching and efficiency are required in various industrial sectors. The problem in inverter drive motors is the inverter surge voltage due to high-speed switching, which can cause partial discharge (PD) and degradation of insulation performance of motors. The purpose of present research is to establish the diagnostic technique for high voltage equipment, based on PD detection by loop sensors. Determination of a PD location in an actual stator core provides its optimal insulation design. In the present paper, the PD location in an actual stator core was determined by detecting the electromagnetic (EM) wave using several loop sensors, located in the depth direction and the circumferential direction of the actual stator core. As a result, the arrival time difference of EM wave was measured at each sensor. The arrival time of EM wave was calculated by cumulative energy method. It can be seen EM waveform arrival time difference method allows PD location with accuracy of 1/48 in the actual stator core.

DOI： 10.1109/CMD.2018.8535958

Scopus

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Consideration of Generation Mechanism of Low Frequency Component of Partial Discharge Signal Detected by Transient Earth Voltage 査読有り

H.Yoshizumi, Y.Nakano, M.Kozako, M.Hikita, Y.Fujii, Y.Nakamura, H.Cho

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P63 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

© 2018 IEEE. Transient earth voltage (TEV) detection method is drawing attention for its readiness to be installed just on the outer wall of existing equipment, and is useful for partial discharge (PD) detection. The purpose of this research is to establish reliable insulation diagnosis technique of high voltage equipment based on partial discharge detection using TEV method. Our previous study showed that TEV sensor dominantly detects high (several 100 MHz) and low frequency (several 10 MHz) components attributed to the electromagnetic wave propagating through space and discharge current flowing through the ground line, respectively. To investigate a mechanism of generated low frequency components further, this paper deals with the effect of the length of PD measurement circuit on the low frequency component detected by TEV sensor by experiments and simulation of electromagnetic wave propagation using finite difference time domain (FDTD) method. As a result, it was found that the low frequency component includes two different kinds of dominant resonance frequencies determined by assuming the measurement circuit to act as a lumped constant electric circuit and as an antenna such as dipole antenna and loop antenna.

DOI： 10.1109/CMD.2018.8535989

Scopus

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Classification of Partial Discharge Sources using Waveform Parameters and Phase-Resolved Partial Discharge Pattern as Input for the Artificial Neural Network 査読有り

T.R.Sukma, U.Khayam, Suwarno, R.Sugawara, H.Yoshikawa, M.Kozako, M.Hikita, O.Eda, M.Otsuka, H.Kaneko, Y.Shiina

The 2018 International Conference on Condition Monitoring and Diagnosis (CMD2018) ( P9 ) 2018年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Australia Perth 2018年09月23日 - 2018年09月26日

© 2018 IEEE. Partial discharge (PD) is one of electrical phenomena which might occur in high voltage (HV) equipment and can be used for diagnosing the condition of the equipment. Artificial neural network (ANN) is then utilized to classify PD source in HV equipment. PD measurements were conducted to generate waveform parameters in laboratory using four kinds of artificial PD sources, three kinds of noise sources by three kinds of sensors (transient earth voltage (TEV) sensor, surface current sensor (SCS) and high frequency current transformer (HFCT)). Nine waveform parameters from one PD event were used for training and testing the ANN (ANN- WP). For further comparison, phase-resolved partial discharge (PRPD) pattern was also generated and used as input data for training and testing the other ANN (ANN-PR). Results reveal that ANN- WP provides >96% of recognition rate while ANN-PR gives >90% of recognition rate. Furthermore, the ANNs are then tested using new different artificial void defect. The results show that the ANN- WP predicted new PD data as void defect with 92 % probability while the ANN-PR prediction probability was found 96%. These results indicate that the waveform parameters can be used as an input data for ANN as well as PRPD pattern to provide sufficient accuracy for identifying the PD source. The results suggest a possibility that developed ANNs can be used as a decision-support tool in HV equipment diagnosis by comparing PD data obtained in the field.

DOI： 10.1109/CMD.2018.8535675

Scopus

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モールド変圧器の交流部分放電特性に及ぼす雷インパルスプレストレスの影響査読有り

丸山裕史, 松尾賢介, 小迫雅裕, 匹田政幸, 飯田和生, 梅村時博, 中村勇介, 中前哲夫, 前田照彦, 東山雅一

電気学会論文誌A 138 ( 8 ) 422 - 427 2018年08月

Impedance Network Modeling of non-linear Restistive Material 査読有り

G.Belijar, L.Hermette, M.Kozako, M.Hikita

International Conference on Dielectrics (ICD2018) ( 203 ) 2018年07月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Hungary Budapest 2018年07月01日 - 2018年07月05日

© 2018 IEEE. Advances in high voltage / high power density apparatus is required for the energy transition challenge. Facing this challenge of intense electrical constraint, non-linear resistive materials are valuable to perform functions such as field grading or surge protection. If great advances have been made regarding these materials, some effort are still necessary on simulating their behavior. In this article, an impedance network modelling method is presented to simulate the response of epoxy/zinc oxide composite.

DOI： 10.1109/ICD.2018.8468501

Scopus

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Partial Discharge Inception Voltage of Enameled Cellular Wire under Impulse Voltage 査読有り

K.Maeda, T.Kubo, T.Uchimura, H.Mizoguchi, M.Kozako, M.Hikita, D.Mutou, K.Tomizawa, K.Ikeda

International Conference on Dielectrics (ICD2018) ( 3 ) 2018年07月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Hungary Budapest 2018年07月01日 - 2018年07月05日

© 2018 IEEE. In order to suppress partial discharge (PD) generated in the wedge gap between an inverter drive motor windings due to overvoltage, the authors have developed a low permittivity film with micro cellular in an insulating layer resin. An attempt is made to measure partial discharge inception voltage (PDIV) for twisted pair sample of insulating film with micro cellular in the resin. This paper deals with experimental and analytical investigation on improved PDIV owing to micro cavities in the insulating layer under AC and impulse voltage application. Measured PDIV under AC and impulse voltage application is interpreted quantitatively in terms of Volume-Time theory which considers the generation probability of initial electrons supplied from both the solid insulating material surface and the wedge gap volume as well as a streamer inception criterion.

DOI： 10.1109/ICD.2018.8470057

Scopus

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Influence of Electromagnetic Sensor Location on Repetitive Partial Discharge Inception Voltage in Actual Stator Core of Inverter Fed Motor 査読有り

M.Hikita, H.Mizoguchi, T.Kubo, T.Uchimura, M.Kozako, J.Sun, A.Izumi, K.Karasawa, T.Hirose, T.Ueno, S.Hiroshima

2018 IEEE Electrical Insulation Conference (EIC2018) 435 - 438 2018年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

USA San Antonio 2018年06月17日 - 2018年06月20日

© 2018 IEEE. Repetitive partial discharge inception voltage (RPDIV) measurement is indispensable for inverter-fed motor when testing the insulation dignity according to IEC 60034-18-41 IS. Our previous study showed detection sensitivity comparison among kinds of electromagnetic (EM) sensors for PD measurement in an actual motor core. This paper deals with an influence of the location of EM sensors on the sensitivity of detected EM wave to quantitatively evaluate RPDIV. As a result, it was found that employing the EM wave sensor located at the furthest position from the PD source on Z axis to detect PD can result in estimating higher RPDIV by 7.5 % at most than an actual one, depending on the sensor location. The possibility of location of a PD source using multiple LSs placed in the actual core is also suggested from differences in the signal strength and time for EM signal to reach multiple LSs.

DOI： 10.1109/EIC.2018.8481091

Scopus

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Properties of thermally aged natural esters used as insulating liquid 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

International Journal on Electrical Engineering and Informatics 10 ( 2 ) 220 - 231 2018年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018, School of Electrical Engineering and Informatics. All rights reserved. An accelerated aging test is an important test to assess a long time performance of an insulation system. This paper deals with the investigation results on thermally aged natural esters insulating liquid used for transformator. Two kinds of monoesters, palm fatty acid ester (PFAE) and stearic/oleic/linoleic acids methyl esters (M182), and one tri-ester, Envirotemp (FR3), were aged at the temperature of 120°C for 60 days. An as-received oil was used as a sample for aging test, so that the presence of a limited amount of air, and thus oxygen, in oil sample could not be avoided. The important properties like appearance, moisture content, acid value, volume resistivity, and breakdown voltage are evaluated at each 15 days interval. Experiment on mineral oil under the same condition was also conducted for comparison. It was observed that the color of the FR3 was changed from light-green to dark-green. PFAE, M182 and mineral oils which were initially transparent became yellow-green, light yellow and brown, respectively. A sludge formation was observed in the mineral oil, whereas the increase in acidity was found in the PFAE and M182 oils. The moisture content of aged PFAE and M182 oils decreased whereas that of aged FR3 and mineral oils increased. The volume resistivity of all tested oils decreased with aging time, whereas their breakdown voltage showed a different behaviours. The breakdown voltage of M182 and mineral oils increased and decreased, respectively, whereas that of PFAE and FR3 relatively unchanged.

DOI： 10.15676/ijeei.2018.10.2.2

Scopus

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PD behaviors of monoester insulating oil under different moisture contents 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

Telkomnika (Telecommunication Computing Electronics and Control) 16 ( 2 ) 481 - 487 2018年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 Universitas Ahmad Dahlan. One of the problems encounters in implementing vegetable oils (natural esters) as a transformer insulating oil is their viscosity which is high. To address this problem, monoester derived from vegetable oil was introduced. This paper deals with partial discharge (PD) behaviors of dry and moist samples of a monoester type insulating oil, palm fatty acid ester (PFAE), under AC high voltage utilizing a needle plane electrode configuration. Variations of average PD charge and PD number against the variation of voltage application, as well as their polarity discrimination under both dry and moist sample conditions are analyzed. PD pulses phase distributions of both dry and moist sample oils are elaborated. Finally, a mechanism of the water molecules effect on PD behavior is proposed based on experimental results and shown schematically.

DOI： 10.12928/TELKOMNIKA.v16i2.7356

Scopus

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Simulation of Electrical Characteristics for Misalignment of Coil in Wireless Power Transfer System Using Repeating Coil 査読有り

A.Imakiire, H.Tokunaga, A.Kawagoe, M.Kozako, M.Hikita

The 6th IIAE International Conference on Industrial Application Engineering 2018( ICIAE2018) ( 18 ) 81 - 88 2018年03月

Novel Partial Discharge Location Algorithm for Next Generation Power Module using Small Loop Sensors 査読有り

J.Maki, Y.Akinaga, M.Kozako, M.Hikita, Y.Nakamura, K.Taniguchi, Y.Ikeda, K.Okamoto

10th International Conference on Integrated Power Electronics Systems(CIPS) ( P2.12 ) 186 - 191 2018年03月

Dielectric Properties and Partial Discharge Inception Voltage of Aluminum Nitride Insulating Substrate at High Temperatures 査読有り

T.Abe, M.Suenaga, A.Imakiire, M.Kozako, M.Hikita, H.Shiota, T.Nishimura, H.Muto

10th International Conference on Integrated Power Electronics Systems(CIPS) ( P2.6 ) 155 - 160 2018年03月

Thermal Characteristic Evaluation and Transient Thermal Analysis of Next-generation SiC Power Module at 250 °C 査読有り

A.Imakiire, M.Kozako, M.Hikita, K.Tatsumi, M.Inagaki, T.Iizuka, H.Narimatsu, N.Sato, K.Shimizu, K.Ueda, K.Sugiura, K.Tsuruta, M.Iida, K.Toda

10th International Conference on Integrated Power Electronics Systems(CIPS) ( P2.9 ) 174 - 179 2018年03月

Aging properties of monoesters and comparison with tri-ester and mineral oil 査読有り

Rajab A., Tsuchie M., Kozako M., Hikita M., Suzuki T.

2017 IEEE 19th International Conference on Dielectric Liquids, ICDL 2017 2017-January 1 - 4 2017年11月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Two types of esters derived from vegetable oil, triglyceride (tri-ester) and monoester, have been implemented as insulation in the oil filled transformer. Tri-ester type is superior in flash point but inferior in viscosity and pour point compared to the monoester type. An accelerated aging test is an important test to assess a long time performance of an insulation system. Two kinds of monoesters, palm fatty acid ester (PFAE) and stearic/oleic/linoleic acids methyl esters (M182), and one tri-ester, Envirotemp (FR3), were thermally aged at the temperature of 120 °C for 60 days. The aging test was performed with the presence of a limited amount of air in oil sample by using as-received oil. The important properties like breakdown voltage, resistivity, and moisture content are evaluated at each 15 days interval. Experiment on mineral oil under the same condition was also conducted for comparison.

DOI： 10.1109/ICDL.2017.8124718

Scopus

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量子化学計算を用いた炭化水素系熱硬化性樹脂の誘電率推定の検討査読有り

渕裕樹, 中迫椋太, 小迫雅裕, 匹田政幸, 亀井伸人

電気学会論文誌A 137 ( 11 ) 626 - 631 2017年11月

記述言語：日本語掲載種別：研究論文（学術雑誌）

© 2017 The Institute of Electrical Engineers of Japan. In recent years, understanding of the characteristic mechanism of electrical insulating materials using quantum chemical calculation has attracted increasing interest. Dielectric properties are one of the important properties in practical use of electrical insulating materials, but there is no precedent investigation for the dielectric properties using quantum chemical calculation. In this paper, the relative permittivity of dicyclopentadiene and tricyclopentadiene resin is estimated by mean of density functional theory and Clausius-Mossotti's, Onsager's or Kirkwood's equations. As a result, estimated values of the relative permittivity are in reasonable agreement with experimental ones. In addition, in order to investigate the dependency of estimated values on molecular modeling, the influence of the number of repeating units was examined. As a result, it was found that the estimated values is almost independent of the number of repeating units. In other words, the calculation model for the permittivity prediction may be sufficient for a small molecular chain as dealt with in this paper.

DOI： 10.1541/ieejfms.137.626

Scopus

CiNii Article

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PD Pattern of Various Defects measured by TEV sensor 査読有り

H.Prasetia, U.Khayam, Suwarno, A.Itose, M.Kozako, M.Hikita

International Conference on High Voltage Engineering and Power Systems (ICHVEPS2017) ( TS1-3 ) 12 - 17 2017年10月

Basic study on measurement of electromagnetic waves emitted by partial discharge in cable joint for high voltage overhead transmission 査読有り

S.Masuda,T.Koga, M.Kozako, M.Hikita, H.Haruyama, I.Kato, H.Sato, F.Aono

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 547 - 550 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. Insulation failure may occur due to aging in cable joint for high voltage overhead transmission. From the view point, this paper deals with the insulation diagnostics by measuring electromagnetic (EM) waves emitted by partial discharge (PD), which is precursory phenomenon of dielectric breakdown. The intensity and frequency spectra of PD radiated EM wave were measured with three different monopole antennas (MA) in three different frequency bands and a high frequency current transformer as a function of the distance between the antenna and PD source located in the cable joint. Experimental results revealed that difference in the arrival time between two MAs was estimated by changing the distance ? d of the three MAs located at 300, 600, and 900mm. It elucidated that the distance dependence of the PD signal can be acquired by the MA, and the method using the multi MAs provides an insight into diagnostics at the insulation failure in the cable joint.

DOI： 10.23919/ISEIM.2017.8166547

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Comparison of insulation characteristics in electrode system with silica filled hydrocarbon-based thermosetting resin 査読有り

Y.Okubo, Y.Fuchi, R.Nakasako, M.Kozako, M.Hikita, N.Kamei

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 532 - 534 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. In order to meet the demand for further high temperature operation and withstand voltage against electric insulating materials, the authors focus on Tricyclopentadiene (TCP) and Dicyclopentadiene (DCP) resins, which belong to hydrocarbon thermosetting resins. We have reported that TCP resin has lower dielectric constant and lower dielectric loss factor while having higher heat resistance than conventional epoxy resin. Our previous report revealed that insulation characteristics of TCP resin with molding the high voltage electrode depend on the interface state between the electrode and the resin. From the viewpoints, this report presents investigation of inherent insulation performance (electric breakdown strength) of the TCP resin using recessed type specimen.

DOI： 10.23919/ISEIM.2017.8166543

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Digest Report of Investigating R&D Committee on Advancing Tailor-made Composite Insulation Materials 査読有り

T.Tanaka, M.Kozako, T.Imai, M.Kurimoto

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) ( DR-5 ) xiv 2017年09月

Digest Report of Cooperative Research Committee on EINA Magazine 査読有り

M.nagao, Y.Inoue, M.kozako

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) ( DR-1 ) x 2017年09月

Repetitive Impulse Voltage Supply and Automatic RPDIV Measuring System 査読有り

K.Umezu, A.Takeshita, M.Hikita, M.Kozako, T.Ueno

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) ( DM-7 ) 794 - 795 2017年09月

The influence of switching impulse voltage superimposition on partial discharge characteristics of oil impregnated paper insulation system and conditions inside its oil gap defect 査読有り

Y.Iwashita, A.Tokudome, N.Yamaguchi, Y.Makino, T.Kurihara, T.Takahashi, M.kozako, M.hikita

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 1 399 - 402 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

The authors have evaluated the possibility of deterioration diagnosis of Oil-filled (OF) cable systems by PD measurement so far. In our previous studies, we confirmed continuous occurrence of PDs even under the design electric field of 275 kY OF cables. Also we confirmed the progress of intermittent occurrence of PDs to continuous one by repeated superimpositions of lightning impulse voltage corresponding to switching surge. However, correlation between PD characteristics and internal conditions of the oil gap defect was not obtained. Therefore, in this study, we experimentally investigated the effects of the switching impulse voltage superimposition that can occur in practical operation of 275 OF cable systems on PD characteristics and we observed the conditions inside the oil gap defect by a CCD camera.

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Sensitivity characteristics of partial discharge electromagnetic sensor located in stator core 査読有り

T.Kubo, T.Uchimura, M.Kozako, M.Hikita, T.Ueno, J.Sun, A.Izumi, K.Karasawa, T.Hirose, S.Hiroshima

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 680 - 683 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. Repetitive partial discharge inception voltage (RPDIV) measurement is indispensable for inverter-fed motor when testing according to IEC 60034-18-41 IS. Our previous study showed sensitivity comparison between kinds of electromagnetic (EM) sensors and a partial discharge (PD) measuring device in an actual motor core. This paper deals with an influence of the position and distance of EM sensor on the sensitivity of detected EM wave to quantitatively evaluate RPDIV. Results revealed that the detected signal attenuation is affected by not only the distance between the PD source and the sensor location but also the existence of the actual core. Furthermore, RPDIV provided by a loop sensor located at 135° around the circumference direction from the bottom of the core was estimated by 10% higher than that determined with a reference LS located just above the PD source which was placed at the bottom of the core. Namely, it is indicated that employing EM wave sensor to detect PD can result in estimating higher RPDIV than actual one. In other words, a correction is necessary for estimating precise RPDIV by multiplying a given factor depending on the size of the core and the location of the EM sensor to measure RPDIV.

DOI： 10.23919/ISEIM.2017.8166582

Scopus

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Propagation characteristics of acoustic wave induced by partial discharge in IGBT module 査読有り

J.Maki, Y.Akinaga, M.kozako, M.Hikita, Y.Nakamura, K.Taniguchi, Y.Ikeda, K.Okamoto

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 668 - 671 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. The next-generation power module is expected to be used in high voltage applications. The key issue in high-voltage power module is the existence of partial discharge (PD). Therefore identifying a PD location leads to a higher voltage operation of power module. PD location could be made by measuring acoustic wave detected by acoustic emission sensors. This paper deals with propagation characteristics of acoustic wave emitted by PD in an IGBT power module.

DOI： 10.23919/ISEIM.2017.8166579

Scopus

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Preparation of fullerene/epoxy resin composite with fine dispersion and its breakdown strength 査読有り

S.Harada, M.Kozako, M.Hikita, T.Igarashi, H.Kaji

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 654 - 656 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. Fullerene is likely to form aggregates so that it is difficult to disperse it well in a polymer matrix, and few reports have been made on electrical insulation properties of fullerene filled composite as electrical insulating material. This paper deals with fullerene dispersion method in conventional epoxy resin (EP) and breakdown strength (BDS) of the composite with different filler loading of fullerene. Composite materials added with fullerenes of 0.1, 0.3, and 0.6 weight% were prepared in a plate shape with a thickness of 0.5 mm using two different dispersion methods, i.e. fullerene dissolved and fullerene direct mixing methods, and neat specimen was also prepared for comparison so as to investigate BDS. As a result, it was found that BDS of fullerene/EP composite with good dispersion greatly increased by 30 %. The increase in BDS of the composite is discussed in terms of the inter-particle distance as an index of the dispersion degree.

DOI： 10.23919/ISEIM.2017.8166575

Scopus

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Permittivity estimation of hydrocarbon-based thermosetting resin using quantum chemical calculation 査読有り

Y.Fuchi, R.Nakasako, Y.Okubo, M.Kozako, M.Hikita, N.Kamei

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 524 - 527 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. In recent years, development of computers and progress of calculation algorithms promote understanding of the various mechanisms of characteristics of electrical insulating materials using quantum chemical calculation. This paper deals with quantum chemical calculation of the relative permittivity ϵrof dicyclopentadiene and tricyclopentadiene resins expected as the next generation electrical insulating materials based on density functional theory and Clausius-Mossotti's, Onsager's or Kirkwood's equation. As a result, estimated values of the relative permittivity are found to reasonably agree with experimental ones. In addition, we investigate the influence of the number of repeating units in the molecular structure on ϵr. As a result, it is found that the estimated ϵris almost independent of the number of repeating units.

DOI： 10.23919/ISEIM.2017.8166541

Scopus

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Influence of electrode interface on insulation property of hydrocarbon-based thermosetting composite with silica filler 査読有り

R.Nakasako, Y.Fuchi, Y.Okubo, M.Kozako, M.Hikita, N..Kamei

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 528 - 531 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. We have been studying electrical insulation properties of hydrocarbon-based thermosetting composite as a development of new functional polymeric insulating material. Our previous reports showed that the composite has advantages in high heat resistance, low dielectric constant and low dielectric loss. These evaluations were performed for the specimen with a shape of plane. Practical application of the composite to the insulation system of high voltage power apparatus needs to estimate properties for molded electrode configuration. However, the hydrocarbon-based thermosetting resin has relatively poor adhesiveness with a metallic material such as a high voltage conductor. Thus, poor adhesion to metal material may cause lowering of the insulation properties. This paper deals with influence of the electrode interface on the insulation properties of the composite specimen filled with silica filler. As a result, it was found that both the rough surface treatment on the electrode and the adhesive monomer loading can avoid formation of void at the interface between the electrode and specimen, resulting in relatively high breakdown strength.

DOI： 10.23919/ISEIM.2017.8166542

Scopus

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Grounding effect on transient earth voltage signal induced by partial discharge in metal box model 査読有り

H.Yoshizumi, T.Koga, M.Kozako, M.Hikita, Y.Fujii, Y.Nakamura, H.Cho

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 555 - 558 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. This paper deals with advancement of insulation diagnosis technology for high voltage equipment by partial discharge (PD) detection using transient earth voltage (TEV) detection method. Our previous study showed that detected TEV signal contains both high-frequency and low-frequency components around 500 MHz and 30 MHz, respectively. To further investigate the principle of detecting the low frequency components, this paper presents experiment and finite difference time domain analysis of TEV signal propagation. Results revealed that the signal intensity detected by TEV sensor with grounding is about five to six times as much as that without the grounding. Furthermore, when grounded, the low frequency components tend to be strongly detected. In other words, it is suggested that PD current including the low frequency component is induced on the surface of the metal box via the ground line, and this component greatly influences the TEV detection intensity.

DOI： 10.23919/ISEIM.2017.8166549

Scopus

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Evolution of PD properties till breakdown in silicon nitride substrate molded with resin 査読有り

Y.Akinaga, J.Maki, M.Kozako, M.Hikita, Y.Nakamura, K.Taniguchi, T.Ikeda, K.Okamoto

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 2 664 - 667 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

© 2017 Institute of Electrical Engineers of Japan. All rights reserved. This paper deals with evolution of partial discharge (PD) occurrence phase and charge (φ-q) characteristics of 0.32 mm thick Si 3 N 4 substrate molded with resin by applying ac 9 kVrms at 60 Hz until breakdown to quantitatively evaluate the degradation degree as well as the lifetime. Experimental results revealed that all specimens broke down just after PD magnitude suddenly increased. This means difficulty to expect the lifetime from only the PD magnitude. On the other hands, it was also found that φ-q characteristics changed continuously until breakdown. Namely, the shape of φ-q characteristics exhibited a rabbit-like pattern a few minutes before breakdown. In addition, the skewness of the pattern of PD distribution was analyzed in the positive and negative phases separately. As a result, the positive and negative skewness has increased three to four times with approaching to the breakdown. Thus, the present research indicates that a statistical parameter skewness of PD occurrence distribution can provide a possibility for expecting the lifetime of Si 3 N 4 insulation substrate molded with resin.

DOI： 10.23919/ISEIM.2017.8166578

Scopus

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Effects of tracking and erosion resistance of nano-boehmite added silicone rubber 査読有り

R.Inoue, T.Kondo, M.Kozako, M.Hikita

2017 International Symposium on Electrical Insulating Materials (ISEIM2017) 1 29 - 31 2017年09月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Japan Toyohashi 2017年09月11日 - 2017年09月15日

The aim of this study is to develop new room temperature vulcanization (RTV) silicone rubber nanocomposites for application to outdoor polymer insulator. This paper deals with effects of addition of nano-scale boehmite filler on tracking, erosion resistance and arcing resistance of silicone rubber. The inclined plane test and the arc resistance test were performed. As a result, it was elucidated that the addition of small amount of nano-boehmite filler is able to increase tracking, erosion and arcing resistance.

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到達時間差法を用いたパワーモジュール内部の部分放電発生位置評定の高精度化検討査読有り

秋永優也, 真木洵耶, 満留博, 小迫雅裕, 匹田政幸, 岡本健次, 池田良成, 谷口克己, 中村瑤子

スマートプロセス学会誌 6 ( 5 ) 175 - 180 2017年09月

AC Partial Discharge Characteristics and Accumulation Charge after Lightning Impulse in Cast Resin Transformer 査読有り

H.Maruyama, M.Kozako, M.Hikita, K.Iida, T.Umemura, Y.Nakamura, T.Maeda, M.Higashiyama, T.Nakamae

The 20th International Symposium on High Voltage Engineering(ISH2017) ( 416 ) 1 - 5 2017年08月

PARTIAL DISCHARGE INCEPTION VOLTAGE MEASUREMENT AND ITS ESTIMATION BY VOLUME-TIME THEORY FOR SF6/PET INSULATED WEDGE GAP UNDER IMPULSE VOLTAGE 査読有り

K.Maeda, M.Kozako, M.Hikita, S.Yoshida, T.Chigiri

The 20th International Symposium on High Voltage Engineering(ISH2017) ( 441 ) 1 - 6 2017年08月

Dielectric properties and creepage discharge of epoxy/silica nanocomposite in mineral oil 査読有り

M.Kurachi, K.Jang, T.Akahoshi, M.Kozako, M.Hikita

19th IEEE International Conference on Dielectric Liquids 2014 (ICDL2017) 2017-January ( 1196 ) 1 - 4 2017年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

UK Manchester 2017年06月25日 - 2017年06月29日

© 2017 IEEE. This paper deals with the effect of the nano filler loading in epoxy resin (EP) on creepage discharge properties of the epoxy/silica nanocomposite (EP/S-NC) in mineral oil under standard lightning impulse voltage application using needle-bar electrode arrangement. Experimental results allow to estimate discharge occurrence probability (Pd) at each voltage level. The relative permittivity and dielectric loss are measured at 50 Hz - 5 MHz for EP/S-NC with a good dispersion of nanoparticles in the base epoxy matrix. As a result, it is found that Pd decreases with increasing the filler loading up to 1 wt%, and then increases. Namely, the nano filler content of 1 wt% produces the best insulation performance in terms of Pd. The relative permittivity of the composite decreases with decreasing the filler loading below 1 wt%, while further increasing nano silica filler loading results in increased έr above 3 wt%.

DOI： 10.1109/ICDL.2017.8124663

Scopus

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Aging Properties of Monoesters and Comparison with Tri-ester and Mineral Oil 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

19th IEEE International Conference on Dielectric Liquids 2014 (ICDL2017) ( 1201 ) 2017年06月

Electrical insulation performance evaluation of PVF wire under thermal and electrical accelerated aging 査読有り

T.Uchimura, T.Kubo, M.Kozako, M.Hikita, K.Shimomura, S.Kawakami, T.Tanaka

19th IEEE International Conference on Dielectric Liquids 2014 (ICDL2017) 2017-January ( 1180 ) 1 - 4 2017年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

UK Manchester 2017年06月25日 - 2017年06月29日

© 2017 IEEE. It is crucial to understand degradation factors under actual operation in the lifetime evaluation of the coil winding of transformer. Polyvinyl formal (PVF) wire is used in oil-immersed transformer. Main degradation factor is considered to be oxidation and damage of the insulation coating due to thermal stress and partial discharge (PD). This paper deals with electrical insulation performance evaluation of twisted-pair specimen with PVF wire after thermal and electrical stress in the insulating oil. This research also deals with evaluation of a relation between the thermal stress and PD inception voltage (PDIV). Furthermore, Voltage-time (V-t) characteristics of twisted-pair specimen is investigated.

DOI： 10.1109/ICDL.2017.8124729

Scopus

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Effect of discharge trace on creeping discharge characteristics in oil/pressboard composite insulation system under impulse voltage application 査読有り

S.Kainaga, S.Yoshida, T.Umemoto, M.Yoshimura, T.Tsurimoto, T.Akahoshi, K.Jang, M.Kurachi, M.Kozako, M.Hikita

19th IEEE International Conference on Dielectric Liquids 2014 (ICDL2017) 2017-January ( 1126 ) 1 - 5 2017年06月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

UK Manchester 2017年06月25日 - 2017年06月29日

© 2017 IEEE. In order to improve the insulation performance of oil-immersed power transformers, the characteristics of the creeping discharge under impulse voltage have been investigated. In this work, by using streak camera, investigations of the influence of the white discharge trace on the creeping discharge characteristics were implemented. The results showed that the velocity of the discharge developing along the white trace was about a thousand times larger than that of the discharge progressing on the pressboard surface. The results also showed that the length of the discharge progressing on the pressboard surface after the white trace formation was shorter than that before the white trace formation. On the other hand, the discharge time delay became larger. These results are thought to be explained by the residual charge generated by the discharge developing along the white trace.

DOI： 10.1109/ICDL.2017.8124708

Scopus

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High accuracy partial discharge location in power module using multiple loop sensors 査読有り

H.Mitsudome, Y.Akinaga, M.Kozako, M.Hikita, Y.Ikeda, K.Taniguchi, Y.Nakamura, K.Okamoto

IEEE International Workshop On Integrated Power Packaging (IWIPP2017) ( 1009 ) 2017年04月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Netherlands Delft 2017年04月05日 - 2017年04月07日

© 2017 IEEE. Existence of partial discharge (PD) is one of the key issues in high-voltage power module. Thus, identifying a PD location in a power module leads to a higher voltage operation of a power module. An attempt is made to identify PD location in an IGBT power module by measuring electromagnetic wave (EMW) detected by multiple loop sensors. In this paper, a novel technique for identification of PD source is proposed by utilizing the polarity reversal of the first rising part of detected EMW signals and Time of Flight (TOF) method with four loop sensors. As the result, it is found that the method utilizing the polarity reversal of EM waveform allows PD location with accuracy of 1 mm. And it is found that TOF method with sampling frequency of 80 GS/s allows PD location with accuracy of 1 mm.

DOI： 10.1109/IWIPP.2017.7936749

Scopus

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Investigation of prototype SiC power module structure for low inductance and high heat operation 査読有り

A.Imakiire, K.Nakamura, H.Tanabe, H.Kaisyakuji, T.Kubo, M.Kozako, M.Hikita

IEEE International Workshop On Integrated Power Packaging (IWIPP2017) ( 1032 ) 2017年04月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Netherlands Delft 2017年04月05日 - 2017年04月07日

© 2017 IEEE. This paper deal with structure for low inductance and high heat operation of silicon carbide (SiC) power module, which attracts attention in terms of high withstand voltage, high efficiency and high heat operation in recent years. First, the parasitic inductance of the power module of two types of structure; a conventional structure which forms the current path in a planar manner and a structure formed three-dimensionally is investigated using electromagnetic field analysis. In addition, thermal resistance of two types of power modules are experimentally evaluated from heat radiation performance. Experimental and simulated results reveals that the three-dimensionally formed power module is superior in the current path, resulting in lower parasitic inductance as well as smaller switching loss. Moreover, on state resistance and leakage current are evaluated at the junction temperature of 250 °C and the problems of power module package under high temperature environment is also investigated.

DOI： 10.1109/IWIPP.2017.7936767

Scopus

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Evaluation on Applicability to Electrical Insulating Material of Hydrocarbon-Based Thermosetting Resin 査読有り

K.Yoshida, M.Kozako, S.Ishibe, M.Hikita , N.Kamei

Electronics and Communications in Japan 100 ( 4 ) 83 - 90 2017年04月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 Wiley Periodicals, Inc. This paper deals with dielectric properties of hydrocarbon-based thermosetting resin to evaluate the applicability to electrical insulating materials. Moreover, higher withstand voltage, lower dielectric constant, and lower moisture absorption are required for the electrical insulating materials. One of the candidate polymer materials satisfying such demands is hydrocarbon-based thermosetting resin, that is, polydicyclopentadiene (P-DCP) and polytricyclopentadiene (P-TCP). We measured the dielectric properties such as dielectric constant, dielectric loss, volume resistivity, and breakdown strength (BDS), and other properties such as moisture absorption, viscosity, mechanical strength, glass transition temperature, and coefficient of linear expansion of those specimens. It was found from the results in particular that P-DCP and P-TCP have the lower dielectric constant and the lower moisture absorption as compared with epoxy resin, while the volume resistivity and the BDS of P-DCP and P-TCP are not different to those of epoxy resin. As a result, it is elucidated that two kinds of hydrocarbon-based thermosetting resin have a potential for application to an electrical insulating material.

DOI： 10.1002/ecj.11953

Scopus

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油/プレスボード複合絶縁系におけるインパルス沿面放電特性に及ぼす白色放電生成物の影響査読有り

赤星卓勇, Jang Kyunghoon, 小迫雅裕, 匹田政幸, 海永壮一朗, 吉田成是, 梅本貴弘, 吉村学, 釣本崇夫

電気学会論文誌A 137 ( 4 ) 188 - 195 2017年04月

記述言語：日本語掲載種別：研究論文（学術雑誌）

© 2017 The Institute of Electrical Engineers of Japan.We have investigated the effect of white discharge trace remaining on pressboard (PB) surface on the impulse creeping discharge characteristics in oil/PB composite insulation system. This paper deals with the effect of the white trace on the partial discharge inception voltage (PDIV), the number of discharge pulses, the discharge charge amount, and the time delay of discharge occurrence under the standard lightning impulse voltage application. Then, we also investigated the mechanism how the white trace affected the creeping discharge characteristics.

DOI： 10.1541/ieejfms.137.188

Scopus

CiNii Article

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Impulse creepage discharge properties of solid coated pressboard/oil composite insulation with rod-plane electrode system 査読有り

K.Jang, T.Akahoshi, M.Kozako, M.Hikita

電気学会論文誌A 137 ( 2 ) 113 - 118 2017年02月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2017 The Institute of Electrical Engineers of Japan.The surface of oil immersed pressboard (PB) influences partial discharge (PD) inception voltage and creepage discharge properties. This paper deals with surface modification of insulating paper by thin solid layer coating such as epoxy resin, Teflon and nano size silica /epoxy resin composites on PB surface to improve electrical insulation properties of oil /pressboard composite insulation system. Five kinds of specimens are prepared with different coating materials to investigate creepage discharge initiation and propagation under positive standard lightning impulse voltage (1.2 /50 μs) using a rod-plane electrode arrangement in mineral oil. Creepage discharge properties of conventional PB in oil/ PB composite insulation system are compared with that of the solid layer coated PB in terms of discharge final propagation length (ld) and PD inception voltage (PDIV) as an inception probability (Pi). The results show that PDIV of the solid layer coated PB increases at all applied impulse voltage levels compared with that of conventional PB. Especially, when the filler content of nano silica added in base epoxy was SP-0.2wt%, PDIV characteristic was improved. The effect of solid layer coating of PB surface on the creepage discharge properties is also discussed in terms of the effects of introduced deep electron traps due to the nano composites coating as well as the drying effect to remove water content and the surface roughness of PB.

DOI： 10.1541/ieejfms.137.113

Scopus

CiNii Article

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Non-empirical (ab initio) molecular orbital method 査読有り

Kozako M.

Advanced Nanodielectrics: Fundamentals and Applications 345 - 351 2017年01月

Low thermal fault gases of various natural monoesters and comparison with mineral oil 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

IEEE Transactions on Dielectrics and Electrical Insulation 23 ( 6 ) 3421 - 3428 2016年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2016 IEEE.Natural ester oils began to be implemented in higher voltage of power transformer in 2002. Gases generated by such oils need to be examined in order to anticipate the use of dissolved gas analysis (DGA) method to diagnose the presence of faults in natural ester filled transformer in service. This paper deals with an analysis of the gas generations of natural monoesters of different molecular structures derived from palm and rice bran oils under localized and low thermal faults ranging from 200 to 300 °C. Types of gases and their generation rates at various temperature levels were investigated. An attempt is made to compare the gas generation tendency between tested oils and commercially available natural ester insulation oil reported in the previous literature as well as mineral oil. The phenomenon of ethane generation by fatty acid monoesters having C-C double bond in their hydrocarbon chains and those without C-C double bond are discussed. Due to the expectation of overheating temperature, the possible implementation of CO/CH4 gas ratio is also evaluated.

DOI： 10.1109/TDEI.2016.006068

Scopus

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Experimental Verification of Operation and Method of Decision of Maximum DC Link Voltage in Wireless Power Transfer System 査読有り

H.Tokunaga, H.Tanabe, A.Imakiire, M.Kozako, M.Hikita

IEEE TENCON 2016 - Technologies for Smart Nation 797 - 800 2016年11月

Dependence of Silica Nano Filler added to Epoxy Resin on Creepage Discharge Properties in Mineral Oil 査読有り

K.Jang, T.Akahoshi, M.Kozako, M.Hikita

10th International Workshop on High Voltage Engineering　and 2016 Japan-Korea Joint Symposium on Electrical Discharge and High Voltage Engineering (IWHV2016 ＆ JK2016） ( ED-16-116 SP-16-045 HV-16-101 ) Vol.1,73 - Vol.1,76 2016年11月

EARLY DETERIORATION OF PALM FATTY ACID ESTERS (PFAE) OIL 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

10th International Workshop on High Voltage Engineering　and 2016 Japan-Korea Joint Symposium on Electrical Discharge and High Voltage Engineering (IWHV2016 ＆ JK2016） ( ED-16-142 SP-16-071 HV-16-127 ) Vol.2,37 - Vol.2,40 2016年11月

Comparison of Electrical Insulation Properties of Hydrocarbon-based - Thermosetting Resin and Epoxy Resin 査読有り

Y.Fuchi, K.Yoshida, M.Kozako, M.Hikita, N.Kamei

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2016) ( 3A-18 ) 133 - 136 2016年10月

Partial Discharge and Breakdown Characteristics of Inverter-fed Motor Winding with Micro Cellular Coating 査読有り

M.Hikita, N.Yanaze, T.Uchimura, M.Kozako, K.Tomizawa, M.Ohya

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2016) ( 4B-36 ) 482 - 485 2016年10月

Partial Discharge Properties of Resin Molded Insulation Substrate after Long Term Voltage Application 査読有り

Y.Akinaga, H.Mitsudome, M.Kozako, M.Hikita, K.Taniguchi, Y.Nakamura, Y.Ikeda, K.Okamoto

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2016) ( 4B-29 ) 453 - 456 2016年10月

Comparison of Sensor Detection Sensitivity in Repetitive Partial Discharge Inception Voltage Measurement for Twisted Pair Placed in Stator 査読有り

K.Nakamura, T.Uchimura, M.Kozako, M.Hikita, T.Ueno, J.Sun, T.Sakurai, K.Nakayama, T.Ikegami, K.Karasawa

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2016) ( 3C-19 ) 239 - 242 2016年10月

Partial Discharge Detection and Induced Surface Current Analysis Using Transient Earth Voltage Method for High Voltage Equipment 査読有り

A.Itose, M.Kozako, M.Hikita

The 2016 International Conference on Condition Monitoring and Diagnosis (CMD2016) ( P1-27 ) 455 - 459 2016年09月

Degradation Diagnosis of Electrical Insulation Performance of 6.6 kV Class Epoxy Resin Insulator Contaminated with Iron Powder and Moisture 査読有り

T.Koga, A.Itose, H.Prasetia, M.Kozako, M.Hikita

The 2016 International Conference on Condition Monitoring and Diagnosis (CMD2016) ( P2-52 ) 803 - 806 2016年09月

Partial Discharge Characteristics of Oil Impregnated Paper Insulation System with Oil Gap under Repetive Impulse Voltage Superimposed on AC Voltage 査読有り

Y.Iwashita, M.Kozako, M.Hikita, Y.Makino, T.Kurihara, T.Takahashi, T.Okamoto

The 2016 International Conference on Condition Monitoring and Diagnosis (CMD2016) ( P1-43 ) 522 - 525 2016年09月

Development of Diagnostic Methods for Vacuum Leakage from Vacuum Interrupter by Partial Discharge Detection 査読有り

S.Yokomichi, M.Kozako, M.Hikita, K.Sato, T.Moriyama, H.Urai, T.Nakaoka, K.Tsuchiya

27th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV2016) ( C1-P-21 ) 611 - 614 2016年09月

Partial Discharge Characteristics Of Wedge-Shaped Gap Between Coated Electrodes In SF6 Under Lightning Impulse Voltage 査読有り

K.Maeda, S.Nakamura, M.Kozako, M.Hikita, S.Yoshida, T.Chigiri

21st International Conference on Gas Discharges and Their Applications (GD2016) ( B6 ) 301 - 304 2016年09月

電界下のエポキシ溶液中無機粒子の挙動に与える各種パラメータの影響査読有り

米須大吾, 松岡直哉, 小迫雅裕, 匹田政幸

電気学会論文誌Ａ 136 ( 9 ) 586 - 591 2016年09月

Basic study on partial discharge location in power module 査読有り

Mitsudome H., Akinaga Y., Matsuo K., Kozako M., Hikita M., Ikeda Y., Taniguchi K., Nakamura Y., Okamoto K.

Proceedings of the 2016 IEEE International Conference on Dielectrics, ICD 2016 1 451 - 454 2016年08月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

© 2016 IEEE. This paper deals with partial discharge (PD) location in a power module by measuring electromagnetic (EM) wave of PD using four loop sensors. As the distance between the sensor and PD source decreases, the peak to peak magnitude of the first wave of detected EM wave was found to increase using four sensors array. An attempt is made to locate PD source using output electromagnetic waves detected four loop sensors by the time of flight method. As a result, the present method is found to allow PD location with location identification error of 5 mm.

DOI： 10.1109/ICD.2016.7547640

Scopus

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Effect of Permittivity Variation on Surface Flashover of GIS Epoxy Spacer Model in SF6 Gas 査読有り

N.Matsuoka, Y.Fuchi, M.Kozako, M.Hikita

International Conference on Dielectrics (ICD2016) ( 1-10 ) 96 - 99 2016年07月

PD Properties and Gases Generated by Palm Fatty Acids Esters (PFAE) Oil 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

International Conference on Dielectrics (ICD2016) ( 6-4 ) 816 - 819 2016年07月

Simulation Analysis of Surface Current as TEV signal caused by Partial Discharge on Post Insulator in Bus Duct 査読有り

H.Prasetia, U.Khayam, Suwarno, A.Itose, M.Kozako, M.Hikita

International Conference on Dielectrics (ICD2016) ( 5a-8 ) 480 - 484 2016年07月

Impulse and Subsequent AC Partial Discharge Properties in Cast Resin Transformer 査読有り

K.Matsuo, A.Inatomi, M.Kozako, M.Hikita, K.Iida, T.Umemura, Y.Nakamura, T.Maeda, M.Higashiyama, T.Nakamae

International Conference on Dielectrics (ICD2016) ( 5a-2 ) 455 - 458 2016年07月

Basic Study on Partial Discharge Location in Power Module 査読有り

H.Mitsudome, Y.Akinaga, K.Matsuo, M.Kozako, M.Hikita, K.Okamoto, K.Taniguchi, Y.Ikeda, Y.Nakamura

International Conference on Dielectrics (ICD2016) ( 5a-1 ) 451 - 454 2016年07月

Study on Streaming Electrification Properties of Palm Fatty Acid Ester (PFAE) Oil due to Aging 査読有り

H.Maryono, A.Rajab, U.Khayam, Suwarno, M.Tsuchie, M.Kozako, M.Hikita, T.Suzuki

International Conference on Dielectrics (ICD2016) ( 3b-4 ) 410 - 413 2016年07月

Nano SiO2/epoxy Coating Effect on Creepage Discharge Characteristics in Oil/Pressboard Composite Insulation System 査読有り

K.Jang, T.Akahoshi, M.Kozako, M.Hikita

International Conference on Dielectrics (ICD2016) ( 3a-5 ) 394 - 397 2016年07月

Effect of Discharge Trace Formation on Creepage Discharge Characteristics in Oil/Pressboard Composite Insulation System under Impulse Voltage Application 査読有り

T.Akahoshi, K.Jang, M.Kozako, M.Hikita, S.Kainaga, S.Yoshida, T.Umemoto, M.Yoshimura, T.Tsurimoto

International Conference on Dielectrics (ICD2016) ( 4-11 ) 342 - 345 2016年07月

炭化水素系熱硬化性樹脂の電気絶縁材料への適用評価査読有り

吉田圭佑, 小迫雅裕, 石辺信治, 匹田政幸, 亀井伸人

電気学会論文誌Ａ 136 ( 5 ) 324 - 329 2016年05月

Characteristics of Discharge Inception across Barrier in the Oil/Pressboard Composite Insulation System 査読有り

S.Yoshida, M.Kozako, M.Hikita, T.Umemoto, S.Kainaga, T.Ishikura, H.Muto, T.Tsurimoto

電気学会論文誌A vol.136 ( No.2 ) 105 - 106 2016年02月

Simulation on the microvaristor chain formation in liquid epoxy under electric field 査読有り

D.Komesu, M.Mori, S.Ishibe, M.Kozako, M.Hikita

IEEE Transactions on Dielectrics and Electrical Insulation 23 ( 1 ) 216 - 221 2016年02月

Study on PD Properties of Palm Fatty Acids Esters Oil 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, T. Suzuki

International Symposium on EcoTopia Science 2015 2015年11月

Impulse Creepage Discharge Properties of Solid Coated Pressboard/Oil Composite Insulation with rod-plane Electrode System 査読有り

K. H. Jang, T. Akahoshi, M. Kozako, M. Hikita

2015 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering ( O-003 ) 2015年11月

Partial Discharge Inception Voltage and Breakdown Voltage of Micro Cellular Resin 査読有り

N.Yanaze, M.Kozako, M.Hikita, K.Tomizawa, M.Ohya

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2015) ( 4B-13 ) 370 - 373 2015年10月

Repetitive Impulse Voltage Generator Development and Waveform Analysis for Testing Insulation Dignity of Inverter-fed Low Voltage Motor 査読有り

M.Hikita, K.Nakamura, M.Kozako, T.Ueno, S.Fukumoto, K.Nakayama, T.Sakurai, T.Ikegami, T.Yoshimitsu, T.Hirose, S.Hiroshima

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2015) ( 4B-14 ) 374 - 378 2015年10月

Partial Discharge Characteristics of Epoxy Composite with Micro-meter Size Hollow Glass Particles 査読有り

T.Hori, N.Yanaze, M.Kozako, M.Hikita, J.Wada, S.Okabe

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2015) ( 4B-12 ) 366 - 369 2015年10月

Effect of Thin Solid Layer Coating on Creepage Discharge Characteristics in Oil/Pressboard Composite Insulation System 査読有り

K.H.Jang, S.Yoshida, M.Kozako, M.Hikita

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2015) ( 8C-5 ) 832 - 835 2015年10月

Partial Discharge Detection by TEV Sensors and Signal Propagation Analysis in Transformer Model 査読有り

A.Itose, Y.Tai, M.Kozako, M.Hikita

19th International Symposium on High Voltage Engineering (ISH) ( 567 ) 2015年08月

Study on Static Electrification of Palm FattyAcid Ester (PFAE) Oil 査読有り

H.Gumilang, M.Tsuchie, M.Kozako, M.Hikita, A.Rajab, T.Suzuki, S.Hatada, A.Kanetani, H.Futakuchi, U.Khayam Suwarno

The 5th International Conference on Electrical Engineering and Informatics 2015 (ICEEI2015) ( 43 ) 234 - 237 2015年08月

Design of Dipole Antenna Model for Partial Discharge Detection in GIS 査読有り

K.Khotimah, U.Khayam, Suwarno, Y.Tai, M.Kozako, M.Hikita

The 5th International Conference on Electrical Engineering and Informatics 2015 (ICEEI2015) ( 36 ) 196 - 201 2015年08月

Electrical Insulation Properties Evaluation of Poly-tricyclopentadiene under High Temperature 査読有り

K.Yoshida, M.Kozako, S.Ishibe, M.Hikita, N.Kamei

11th International Conference on The Properties and Applications of Dielectric Materials (ICPADM2015) ( SC0-17 ) 2015年07月

Comparison of Low Thermal Fault Gases of Various Fatty Acid Mono Esters 査読有り

A.Rajab, M.Tsuchie, M.Kozako, M.Hikita, S.Hatada, T.Suzuki, A.Kanetani

11th International Conference on The Properties and Applications of Dielectric Materials (ICPADM2015) ( MD1-2 ) 2015年07月

Electric Field Grading of Gas Insulated Switchgears with Microvaristor Composites 査読有り

N.Matsuoka, D.Komes, M.Mori, M.Kozako, M.Hikita, S.Ishibe

11th International Conference on The Properties and Applications of Dielectric Materials (ICPADM2015) ( IE2-4 ) 2015年07月

Partial Discharge Inception Voltage of Pressurized Gas Insulation Encapsulation Used for High-Temperature and High-Voltage Power Module 査読有り

H.Mitsudome, K.Koyanagi, A.Imakiire, M.Kozako, M.Hikita, Z.Valdez-Nava, S.Dinculescu, T.Lebey

The 11th IEEE International Conference on Power Electronics and Drive Systems (PEDS 2015) ( 387 ) 118 - 121 2015年06月

Characterization of Contactless Power Transfer System and Investigation of Core Shape for AGV Application 査読有り

T.Kojima, H.Tanabe, A.Imakiire, K.Fuji, M.Kozako, M.Hikita, Y.Imoto, K.Honda

The 11th IEEE International Conference on Power Electronics and Drive Systems (PEDS 2015) ( 284 ) 703 - 706 2015年06月

Comparison Performance of Si-IGBT and SiC-MOSFET Used for High Efficiency Inverter of Contactless Power Transfer System 査読有り

H.Tanabe, T.Kojima, A.Imakiire, K.Fuji, M.Kozako, M.Hikita

The 11th IEEE International Conference on Power Electronics and Drive Systems (PEDS 2015) ( 419 ) 707 - 710 2015年06月

Evaluation of Novel Impulse Voltage Generator for Qualification Test of IEC60034-18-42 査読有り

T.Ueno, H.Nakaya, M.Kozako, M.Hikita, T.Tsuda, T.Kisakibaru, T.Yoshimitsu, T.Hirose, S.Hiroshima

2015　IEEE Electrical Insulation Conference (EIC2015) ( P2-18 ) 297 - 300 2015年06月

Effect of X-ray Irradiation on Partial Discharge Inception and Extinction Characteristics in Cast Resin 査読有り

A.Inatomni, M.Kozako, M.Hikita, K.Iida, T.Umemura, Y.Nakamura, T.Maeda, M.Higashiyama

2015　IEEE Electrical Insulation Conference (EIC2015) ( 24.4 ) 575 - 578 2015年06月

エナメル皮膜リボン線の部分放電開始電圧特性と発生箇所の同定査読有り

中屋裕貴, 小迫雅裕, 匹田政幸, 冨澤恵一, 大矢真, 武藤大介

電気学会論文誌A vol.135 ( No.2 ) 107 - 112 2015年02月

エポキシ中のµバリスタ粒子チェーン制御法に関する検討査読有り

森匡史, 米須大吾, 小迫雅裕, 匹田政幸, 石辺信治

電気学会論文誌A vol.135 ( No.2 ) 115 - 116 2015年02月

オレフィン系熱硬化性ポリジシクロペンタジエンとエポキシ樹脂の誘電特性の比較査読有り

増崎裕季, 大木義路, 田付強, 小迫雅裕, 亀井伸人

電気学会論文誌A vol.135 ( No.2 ) 82 - 87 2015年02月

Comparative study of partial discharge characteristics and dissolved gas analysis on palm-based oil as insulating material 査読有り国際誌

A.Susilo, J.Muslim, M.Hikita, M.Kozako, M.Tsuchie, Y.Arief, N.Muhamad, T.Suzuki, S.Hatada, A.Kanetani, T.Kano, Suwarno, U.Khayam

2nd IEEE Conference on Power Engineering and Renewable Energy 2014(ICPERE) ( 10B2-4 ) 232 - 236 2014年12月

ナノフィラーが拓く新しい絶縁材料の世界

今井隆浩, 栗本宗明, 小迫雅裕, 水谷嘉伸, 田中祀捷

Polyfile ( 株式会社大成社 ) 51 ( 609 ) 50 - 55 2014年11月

Partial Discharge Phenomena in Medium Vacuum Region of Vacuum Interrupter and Application to Fault Diagnosis 査読有り

T.Nakaoka, Y.Tai , M.Kozako, M.Hikita, M.Kamarol, K.Sato, N.Tetsu, H.Urai, K.Tsuchiya

The 9th International Workshop on High Voltage Engineering (IWHV) Vol.2 ( ED-14-118 SP-14-74 HV-14-130 ) 57 - 62 2014年11月

Partial Discharge Inception Voltage Measurement and Location Identification of Enamel Coating Ribbon Wire Used for Low-Voltage Motors 査読有り

N.Yanaze, N.Nakaya, M.Hikita, M.Kozako, K.Tomizawa, M.Ohya

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2014) ( 3B-12 ) 192 - 195 2014年10月

Simulation on the Formation of Microvaristor Chains in Liquid Epoxy Resin Under Electric Field 査読有り

D.Komesu, M.Mori, S.Ishibe, M.Kozako, M.Hikita

IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2014) ( 8A-7 ) 691 - 694 2014年10月

Development of Partial Discharge Detection and Diagnostic Methods of Vacuum Circuit Breaker 査読有り

T.Nakaoka, K.Mohamad, M.Kozako, M.Hikita, K.Sato, N.Tetsu, H.Urai, K.Tsuchiya

26th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV2014) ( C1-P-154 ) 485 - 488 2014年09月

Construction of Measurement System of PD Phenomena in Medium Vacuum Region of Vacuum Interrupter 査読有り

M.Kamarol, T.Nakaoka, M.Kozako, M.Hikita, K.Sato, N.Tetsu, H.Urai, K.Tsuchiya

26th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV2014) ( C1-P-176 ) 489 - 492 2014年09月

Study on Detection Signal Identification of Prototype Online Partial Discharge Monitoring and Diagnosis System in High Voltage Electric Equipment 査読有り

Y.Tai, N.Yasukochi, M.Kozako, M.Hikita, A.Suizu, N.Yamamura

The 2014 International Conference on Condition Monitoring and Diagnosis (CMD2014) ( OF-04 ) 443 - 446 2014年09月

Fundamental Characteristics of Repetitive Impulse Generator for Detecting Partial Discharge 査読有り

T.Ueno, H.Nakaya, M.Kozako,M.Hikita, T.Ikegami, T.Yoshimitsu, T.Hirose, S.Hiroshima

5th Euro Asian Pulsed Power Conference ( P1-23 ) 2014年09月

Characteristics of Discharge Progress across Barrier in the Oil/Pressboard Composite Insulation System under Impulse Voltage Application 査読有り

S.Yoshida1, M.Kozako, M.Hikita, T.Umemoto, S.Kainaga, H.Muto, T.Tsurimoto

18th IEEE International Conference on Dielectric Liquids 2014 (ICDL2014) ( 156 ) 2014年06月

Characteristics of Partial Discharge in the Oil Gap Separated by Pressboard Barrier in Oil/Pressboard Composite Insulation System 査読有り

T.Umemoto, S.Kainaga, H.Muto, T.Tsurimoto, S.Yoshida, M.Kozako, M.Hikita

18th IEEE International Conference on Dielectric Liquids 2014 (ICDL2014) ( 154 ) 2014年06月

Study on Influence of Oxidation on Static Electrification in Transformer Oil 査読有り

K.Shima, M.Tsuchie, M.Kozako, M.Hikita, Y.Gosho

18th IEEE International Conference on Dielectric Liquids 2014 (ICDL2014) ( 159 ) 2014年06月

Study on The Formation of Microvaristor Chains in Composite Varistors and Their Electrical Characteristics 査読有り

M.Mori, D.Komesu, S.Ishibe, M.Kozako, M.Hikita

2014　IEEE Electrical Insulation Conference (EIC2014) ( S15-4 ) 483 - 487 2014年06月

Characteristics of Discharge Generation across Insulation Barrier in the Oil/Pressboard Composite Insulation System 査読有り

S.Yoshida, M.Kozako, M.Hikita, T.Umemoto, S.Kainaga, H.Muto, T.Tsurimoto

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( VA12 ) 225 - 228 2014年06月

Effects of Nano-alumina Hydrate Coating for Conductive Fillers on Dielectric Properties of Epoxy Composite Materials 査読有り

M.Kozako, M.Hikita, M.Sato, G.Sato, Z.Valdez-Nava, S.Diaham, T.Lebey

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( C5 ) 77 - 80 2014年06月

Evaluation of Partial Discharge Inception Voltage of Bonding-less Gas Insulation Packaging for High Temperature and High Voltage Power Module 査読有り

K.Koyanagi, A.Yamane, A.Imakiire, M.Kozako, M.Hikita, S.Dinculescu, Z.Valdez-Nava, T.Lebey

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( VB17 ) 425 - 428 2014年06月

Dielectric Properties of Olefin-based Thermosetting Resin for Application to Electrical Insulating Material 査読有り

K.Yoshida, M.Kozako, S.Ishibe, M.Hikita, N.Kamei

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( VB5 ) 378 - 380 2014年06月

Comparison of Dielectric Properties among Polydicyclopentadiene Resin, Epoxy Resin and Their Composites with Microsized SiO2 Fillers 査読有り

Yuki Masuzaki, Yoshimichi Ohki, and Masahiro Kozako

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( VB4 ) 374 - 377 2014年06月

Orientation Effect of Nano-Alumina Coated Conductive Fillers on Dielectric Properties of Epoxy Composites 査読有り

K.Ushijima, M.Kozako, M.Hikita

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( PA10 ) 323 - 326 2014年06月

Effects of Motorette Structure and Vanish Treatment on Repetitive Partial Discharge Inception Voltage Measurement Test in Inverter Surge Insulation 査読有り

H.Nakaya, N.Yanaze, M.Kozako, M.Hikita, T.Ueno, T.Yoshimitsu, K.Nakayama, T.Sakurai, T.Hirose, S.Hiroshima

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( VA23 ) 268 - 271 2014年06月

Study of Direction Identification of Partial Discharge Using Multi Small Loop Sensors 査読有り

A.Inatomi, S.Makki, M.Kozako, M.Hikita, T.Umemura, K.Iida, Y.Nakamura, T.Hirose, T.Maeda, M.Higashiyama

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( VA17 ) 245 - 248 2014年06月

UHF Sensor Optimization Used for Detecting Partial Discharge Emitted Electromagnetic Wave in Gas Insulated Switchgear 査読有り

I.Suprianto,U.Khayam, Suwarno, K.Nishigouchi, M.Kamaro, M.Kozako, M.Hikita

2014 International Symposium on Electrical Insulating Materials (ISEIM2014) ( VA13 ) 229 - 232 2014年06月

Modeling of Early Stage Partial Discharge and Overheating Degradation of Paper-oil Insulation 査読有り

M.Tsuchie, M.Kozako, M.Hikita, E.Sasaki

IEEE Transactions on Dielectrics and Electrical Insulation 21 ( 3 ) 1342 - 1349 2014年06月

Basic Investigation of Epoxy Resin Coatings with Dispersed Carbon Nanotubes 査読有り

M.Kozako, H.Nakatsu, H.Toda, S.Yamada, K.Yoshinaga, M.Hikita, D.Hirata, T.Miyamoto, M.Takei

Electronics and Communications in Japan 97 ( 6 ) 24 - 32 2014年06月

A New Concept Varistor With Epoxy/Microvaristor Composite 査読有り

S.Ishibe, M.Mori, M.Kozako, M.Hikita

IEEE Transactions on Power Delivery 29 ( 2 ) 677 - 682 2014年04月

Evaluation of Detection Signal Characteristics on Prototype Online Partial Discharge Monitoring and Diagnosis System in High Voltage Electric Equipment 査読有り

Y.Tai, N.Yasukochi, M.Kozako, M.Hikita, A.Suizu, N.Yamamura

International Symposium on EcoTopia Science 2013 ( 1296 ) 2013年12月

Barrier Effect on Creeping Discharge under Impulse Voltage Application in Oil/Pressboard Composite Insulation System 査読有り

S.Yoshida, M.Kozako, M.Hikita, T.Umemoto, S.Kainaga, H.Muto, T.Tsurimoto

International Symposium on EcoTopia Science 2013 ( 1298 ) 2013年12月

Effect of the presence of epoxy spacer on transmission rate of electromagnetic wave propagating through T-branch of 66 kV GIS model tank 査読有り

U.Khayam, M.Kozako, M.Hikita, T.Hoshino, S.Maruyama, J.Wada, S.Okabe

IEEE Transactions on Dielectrics and Electrical Insulation 20 ( 6 ) 2254 - 2261 2013年12月

Waveform Estimation of Particle Discharge Currents in Straight 154 kV GIS Using Electromagnetic Wave Propagation Simulation 査読有り

K.Nishigouchi, M.Kozako, M.Hikita, T.Hoshino, S.Maruyama, T.Nakajima

IEEE Transactions on Dielectrics and Electrical Insulation 20 ( 6 ) 2239 - 2245 2013年12月

Co-fired AlN-TiN assembly as a new substrate technology for high-temperature power electronics packaging 査読有り

Zarel Valdez-Nava, Sophie Guillemet-Fritsch, Marc Ferrato, Masahiro Kozako, Thierry Lebey

Ceramics International 39 ( 8 ) 8743 - 8749 2013年12月

Partial Discharge Inception Voltage of Enamel Twisted-pair Samples with Several Laminated Insulation layers 査読有り

H.Nakaya, M.Kozako, M.Hikita, M.Ohya, D.Muto, K.Tomizawa

IEEE Conference on Electrical Insulation and Dielectric Phenomena ( 8B-29 ) 1270 - 1273 2013年10月

Evaluation of Novel Impulse Voltage Generator for Detecting Partial Discharge 査読有り

T.Ueno, H.Nakaya, M.Kozako, M.Hikita, T.Ikegami, T.Sakurai, H.Ogawa, T.Kisakibaru, S.Yamada, T.Yoshimitsu, T.Hirose, S.Hiroshima

IEEE Conference on Electrical Insulation and Dielectric Phenomena ( 8B-15 ) 1213 - 1216 2013年10月

Enhanced Bowtie UHF Antenna for Detecting Partial Discharge in Gas Insulated Substation 査読有り

J.Muslim, A.Susilo, K.Nishigouchi, M.Kozako, M.Hikita, Y.Z.Arief, U.Khayam, Suwarno

2013 48th International Universities' Power Engineering Conference (UPEC) ( 97 ) 2013年09月

Investigation of partial discharge characteristics induced by X-ray irradiation in artificial cavity in epoxy resin 査読有り

Masakazu Higashiyama, Hajime Takada, Masayuki Hayashi, Masahiro Kozako, Masayuki Hikita, Shuhei Nakamura, Tokihiro Umemura, Yusuke Nakamura, Tatsuya Hirose

Electrical Engineering in Japan 184 ( 4 ) 1 - 9 2013年09月

Characteristics of Creepage Discharge under Impulse Voltage Application in Oil/Pressboard Composite Insulation System 査読有り

S.Yoshida, N.Morita, M.Kozako, M.Hikita, T.Umemoto, S.Kainaga, H.Muto, T.Tsurimoto

18th International Symposium on High Voltage Engineering (ISH) ( PC-15 ) 635 - 640 2013年08月

Current Waveform Estimation of PD in Straight 154 kV GIS Using Electromagnetic Wave Propagation Simulation 査読有り

K.Nishigouchi, M.Kozako, M.Hikita, T.Hoshino, S.Maruyama, T.Nakajima

18th International Symposium on High Voltage Engineering (ISH) ( PD-30 ) 1031 - 1036 2013年08月

Electrical Characteristics and Voltage Limiting Effect of Epoxy/ZnO-particle Composite Varistors 査読有り

M.Mori, S.Ishibe, M.Kozako, M.Hikita

18th International Symposium on High Voltage Engineering (ISH) ( OE1-05 ) 1166 - 1171 2013年08月

Study on Static Electrification of Aged Oil and Restrain Mechanism of BTA through Acceleration Test 査読有り

K.Shima, M.Tsuchie, M.Kozako, M.Hikita, H.Fukuda

18th International Symposium on High Voltage Engineering (ISH) ( OE6-05 ) 1338 - 1342 2013年08月

Effects of Addition of Nano-scale Silica Filler on Erosion, Tracking Resistance and Mechanical Properties of Silicone Rubber 査読有り

R.Inoue, T.Kondo, T.Nakamura, M.Kozako, M.Hikita

18th International Symposium on High Voltage Engineering (ISH) ( PE-16 ) 1511 - 1515 2013年08月

Application of UHF Method for the Measurement of Partial Discharges in the Transformer Model 査読有り

S.Yoshida, K.Kono, M.Uchiyama, S.Yamada, N.Morita, M.Kozako, M.Hikita

18th International Symposium on High Voltage Engineering (ISH) ( OF4-06 ) 1856 - 1860 2013年08月

Construction and Evaluation of Prototype Online PD Monitoring and Diagnosis System in High Voltage Electric Equipment 査読有り

Y.Tai, M.Kozako, M.Hikita, I.Nakamura, N.Yamamura, A.Suizu

18th International Symposium on High Voltage Engineering (ISH) ( PF-42 ) 2145 - 2149 2013年08月

Partial Discharge Induced Electromagnetic Wave Propagation Analysis and Detection Using UHF Sensor in Transformer 査読有り

M.Hikita, N.Morita, M.Kozako, S.Yoshida, M.Uchiyama, S.Yamada

18th International Symposium on High Voltage Engineering (ISH) ( OF4-01 ) 1829 - 1832 2013年08月

Experimental Investigation on Erosion Resistance and Hydrophobicity of Silicone Rubber Nanocomposite 査読有り

T.Nakamura, M.Kozako, M.Hikita, R.Inoue, T.Kondo

The 11th IEEE International Conference on Solid Dielectrics ( 19 ) 230 - 233 2013年06月

Effect of X-ray irradiation on partial discharge inception and extinction voltage characteristics of cast resin transformer insulation system 査読有り

S.Makki, M.Kozako, M.Hikita, K.Iida, T.Umemura, S.Nakamura, Y.Nakamura, T.Hirose, T.Maeda, M.Higashiyama

The 11th IEEE International Conference on Solid Dielectrics ( 55 ) 79 - 82 2013年06月

Charge Behavior of Epoxy/Silica Nanocomposites under AC High Fields 査読有り

Y.Watanabe, K.Tohyama, M.Kozako, S.Kawano, K.Ito, H.Miyake, Y.Tanaka, Y.Hirose, Y.Ohki

The 11th IEEE International Conference on Solid Dielectrics ( 220 ) 892 - 895 2013年06月

Improvement of Bowtie UHF Antenna Model for Detecting PD in GIS 査読有り

J. Muslim A.Susilo, K.Nishigouchi, Yanuar Z. Ariefd, U.Khayam, Suwarno, M.Kozako, M.Hikita

The 4th International Conference on Electrical Engineering and Informatics 2013(ICEEI2013) ( 1 ) 227 - 234 2013年06月

Automatic Repetitive PD Inception Voltage Measurement of Motorette Sample Simulating Inverter-fed Motor Insulation by Using a Repetitive Voltage Impulse Generator 査読有り

M.Hikita, T.Ueno, Y.Kudo, M.Kozako, H.Ogawa, T.Sakurai, K.Nakayama, T.Yoshimitsu, T.Hirose, S.Hiroshima

The 12thInternational Electrical Insulation Conference 24 - 28 2013年05月

Fabrication and Evaluation of SiC Inverter Using SiC-MOSFET 査読有り

A.Yamane, K.Koyanagi, M.Kozako, K.Fuji, M.Hikita

The IEEE 10th International Conference on Power Electronics and Drive Systems 1029 - 1032 2013年04月

Development of A New Package for Next Generation Power Semiconductor Devices: toward High Temperature and High Voltage Applications 査読有り

K.Koyanagi, A.Yamane, M.Kozako, I.Omura, M.Hikita, Z.Valdez-Nava, S.Dinculescu, T.Lebey

The IEEE 10th International Conference on Power Electronics and Drive Systems ( B2L-G01-9239 ) 512 - 516 2013年04月

高熱伝導エポキシ複合材料の低フィラー化技術

小迫雅裕

Polyfile ( 株式会社大成社 ) 51 ( 588 ) 30 - 33 2013年02月

モールド絶縁系における微小空気ギャップの絶縁特性（２）－MGM,MGI電極系の部分放電挙動－査読有り

東山雅一, 鈴木勇人, 広瀬達也, 前田照彦, 中村修平, 梅村時博, 小迫雅裕, 匹田政幸村時博, 中村勇介, 広瀬達也

電気学会論文誌B vol.133 ( No.2 ) 203 - 209 2013年02月

Effects of nanofiller materials on the dielectric properties of epoxy nanocomposites 査読有り

J. Katayama, Y. Ohki, N. Fuse, M. Kozako, T. Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 20 ( 1 ) 157 - 165 2013年02月

Packaging of SiC-SBD for High Temperature Operation 査読有り

Z. Valdez-Nava, M. Kozako, S. Dinculescu, I.Omura, M. Hikita, T. Lebey

The 14th International Conference on Electronics Materials And Packaging (EMAP2012) ( P082 ) 428 - 431 2012年12月

Partial discharge characteristics in epoxy cast molding insulation system by X-ray irradiation 査読有り

S.Makki, M.Kozako, M.Hikita, S.Nakamura, K.Iida, T.Umemura, Y.Nakamura, T.Hirose, T.Maeda, M.Higashiyama

Joint Conference of IWHV 2012 & JK 2012 on ED & HVE 1 ( ED-12-108 SP-12-034 HV-12-037 ) 13 - 17 2012年11月

Numerical Analysis of PD emitted Electromagnetic wave propagation in Oil-immersed Transformer 査読有り

N.Morita, M.Kozako, M.Hikita, S.Yoshida, M.Uchiyama, S.Yamada

Joint Conference of IWHV 2012 & JK 2012 on ED & HVE 1 ( ED-12-113 SP-12-039 HV-12-042 ) 39 - 43 2012年11月

Effects of coating of epoxy/CNT composites on surface flashover characteristics 査読有り

H.Nakatsu, M.Kozako, M.Hikita, D.Hirata, Y.Sato, M.Takei, H.Toda, K.Yoshinaga

Joint Conference of IWHV 2012 & JK 2012 on ED & HVE 2 ( ED-12-131 SP-12-057 HV-12-060 ) 23 - 26 2012年11月

Effects of Addition of Nano-scale Silica Filler on Erosion, Tracking Resistance and Hydrophobicity of Silicone Rubber 査読有り

T.Nakamura, M.Kozako, M.Hikita, R.Inoue, T.Kondo

Joint Conference of IWHV 2012 & JK 2012 on ED & HVE 2 ( ED-12-144 SP-12-070 HV-12-073 ) 85 - 89 2012年11月

インバータサージ部分放電測定における繰り返しインパルス電圧発生装置の構築と特性評価査読有り

上野崇寿, 工藤祐紀, 小迫雅裕, 匹田政幸, 櫻井孝幸, 小川弘之, 山田慎一郎, 吉満哲夫, 廣瀬達也, 廣島聡

電気学会論文誌A 132 ( 11 ) 965 - 971 2012年11月

Oil Gap Dependence of Partial Discharge Starting Point in the Oil / Pressboard Composite Insulation System 査読有り

T.Umemoto, S.kainaga, T.Tsurimoto, H.Muto, T.Ishikura, N.Sugitani, N.Morita, M.Kozoko, M.Hikita

The 15th International Conference on Electrical Machines and Systems (ICEMS2012) ( LS2E-3 ) 2012年10月

Development of Repetitive Voltage Impulse Generator and Automatic Repetitive PD Inception Voltage Measurement System for Testing Inverter-fed Motor Insulation 査読有り

M.Hikita, T.Ueno, Y.Kudo, M.Kozako, H.Ogawa, T.Sakurai, K.Nakayama, T.Yoshimitsu, T.Hirose, S.Hiroshima

2012 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2012) ( 32 ) 145 - 148 2012年10月

Effect of Electric Field Application during Curing Process on Thermal Conductivity of Epoxy Composite Materials with Low Content Inorganic Particles 査読有り

S.Kinoshita, M.Kozako, M.Hikita, T.Tanaka

2012 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2012) ( 42 ) 187 - 190 2012年10月

Fundamental Investigation of Dielectric Phenomena in Epoxy Composites during Curing Process under a Uniform Electric Field 査読有り

M.Kozako, Z.Valdez-Nava, S.Diaham, S.Dinculescu, T.Lebey

2012 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2012) ( 129 ) 547 - 550 2012年10月

Process Influence on the Moisture Absorption in a Polymer Nanocomposite 査読有り

F.Saysouk, S.Diaham, M.L.Locatelli, B.Schlegel, V.Salles, Z.Valdez-Nava, M.Kozako, T.Lebey, E.Flahaut

2012 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2012) ( 129 ) 547 - 550 2012年10月

Basic discussion for coating of epoxy resin with carbon nano-tube dispersion 査読有り

Kozako M., Nakatsu H., Toda H., Yamada S., Yoshinaga K., Hikita M., Hirata D., Miyamoto T., Takei M.

IEEJ Transactions on Fundamentals and Materials 132 ( 9 ) 773 - 779 2012年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

Multi-walled carbon nano-tubes (CNT)/epoxy nano-composites were fabricated and coated onto epoxy insulating substrates in order to uniformize the surface conductivity. The effects of polymer functionalization of CNT were investigated on the dispersion of CNT in an epoxy matrix and the electrical surface conductivity. It was elucidated that grafting polymer molecules onto the CNT surface improve the dispersion of CNT in an epoxy matrix compared to those containing CNT without functionalization. The surface conductivity of nano-composites decreases thanks to uniform dispersion of CNT. © 2012 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.132.773

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84867068109&origin=inward

Fabrication of Silicone Rubber Nanocomposites and Quantitative Evaluation of Dispersion State of Nanofillers 査読有り

M.Kozako, T.Tominaga, M.Hikita, G.Ueta, S.Okabe, T.Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 19 ( 5 ) 1760 - 1767 2012年10月

Characteristics of PD Induced Electromagnetic Wave Propagating through T-Branch of 154kV GIS in the Presence of Epoxy Spacer 査読有り

U.Khayam, T.Hoshino, T.Nakajima, S.Maruyama, K.Nishigouchi, M.Kozoko, M.Hikita

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( A-53 ) 379 - 382 2012年09月

PD Pattern of Various Defects Measured by UHF External Sensor on 66kV GIS Model 査読有り

W.Anggoro, Sriyono, K.Nishigouchi, U.Khayam, Suwarno, M.Kozako, M.Hikita, K.Urano, M.Chen

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( A-192 ) 954 - 947 2012年09月

Influence of Spacer Aperture Size on PD-Induced Electromagnetic Wave Measured with UHF External Sensor in 66kV GIS Model 査読有り

W.Anggoro, Sriyono, K.Nishigouchi, U.Khayam, Suwarno, M.Kozako, M.Hikita, K.Urano, M.Chen

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( A-191 ) 387 - 391 2012年09月

New Partial Discharge Location Method in Power Tranceformer based on Acoustic Wave Propagation Characteristics using Numerical Simulation 査読有り

M.Kozako, H.Murayama, M.Hikita, K.Kashine, I.Nakamura, H.Koide

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( A-235 ) 854 - 857 2012年09月

Effect of Excitation Current Waveform on PD Induced Electromagnetic Wave Propagation and Attenuation in Straight 154kV GIS Model 査読有り

K.Nishigouchi, M.Kozako, M.Hikita, T.Hoshino, S.Maruyama, T.Nakajima, U.Khayam

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( A-281 ) 309 - 312 2012年09月

Recent Progress in Diagnosis of Transformers using Non-Conventional Partial Discharge Measurements 査読有り

M.Hikita, M.Kozako

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( IL-1 ) 193 - 197 2012年09月

Characteristics of External Loop Sensor Located Near Bushing on Partial Discharge Measurement 査読有り

Sriyono, Y.Kim, U.Khayam, Swarno, M.Hikita

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( A-193 ) 320 - 323 2012年09月

Study of Partial Discharge Induced Electromagnetic Wave Propagation Property in Power Transformer Model 査読有り

N.Morita, M.Kozako, M.Hikita, S.Yoshida, M.Uchiyama, S.Yamada

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( A-136 ) 44 - 47 2012年09月

Sensitivity Verification and Determination of the Best Location of External UHF Sensors for PD Measurement in GIS 査読有り

Sriyono, W.Anggoro, K.Nishigouchi, U.Khayam, Suwarno, M.Kozako, M.Hikita, K.Urano, M.Chen

International Conference on Condition Monitoring and Diagnosis (CMD2012) ( A-190 ) 698 - 701 2012年09月

アルミナ被覆膜で絶縁化した熱伝導フィラー

佐藤護郎、佐藤正淳、匹田政幸、小迫雅裕

日本プラスチックス工業連盟誌　プラスチックス ( 日本工業出版 ) 2012 ( 9 ) 40 - 43 2012年09月

カーボンナノチューブ分散エポキシ樹脂コーティングの基礎的検討査読有り

小迫雅裕, 中津秀幸, 戸田弘明, 山田修平, 吉永耕二, 匹田政幸,　平田大裕, 宮本剛寿, 武井雅文

電気学会論文誌A 132 ( 9 ) 773 - 779 2012年09月

海外駐在記事：仏国ポールサバティエ大学滞在記

小迫雅裕

電気学会論文誌Ｂ ( 電気学会 ) 132 ( 8 ) NL8_4 2012年08月

TiN/AlN ceramic substrates for high temperature power electronics applications 査読有り

Z.Valdez-Nava, M.Ferrato, S.Guillmet-Fritsch, M.Kozako, T.Lebey

The Electroceramics 13 ( P.12 ) 2012年06月

Partial Discharge Properties of Ester Oils Having Different Molecular Structures 査読有り

M.Hikita, J.Tokiyoshi, M.Tsuchie, M.Kozako, T.Suzuki, A.Kanetani, T.Kano

2012 IEEE International Symposium on Electrical Insulation (ISEI2012) ( 7 ) 26 - 29 2012年06月

X線照射によるエポキシ樹脂中の人工ボイド内部分放電特性の検討査読有り

東山雅一，髙田　一, 林　昌幸, 小迫雅裕, 匹田政幸, 中村修平, 梅村時博, 中村勇介, 広瀬達也

電気学会論文誌A 132 ( 4 ) 284 - 290 2012年04月

屋外絶縁用ナノベーマイトアルミナ充填シリコーンゴムの創製とその特性の基礎的検討査読有り

小迫雅裕, 東小路政史, 匹田政幸, 田中祀捷

電気学会論文誌A 132 ( 3 ) 257 - 262 2012年03月

エポキシ樹脂中ボイド放電におけるX線照射効果の物理的考察査読有り

林　昌幸, 髙田　一, 小迫雅裕, 匹田政幸, 中村修平, 梅村時博, 中村勇介, 広瀬達也, 東山雅一

電気学会論文誌A 132 ( 2 ) 154 - 155 2012年02月

Development of Epoxy/BN Composites with High Thermal Conductivity and Sufficient Dielectric Breakdown Strength, Part II -Breakdown strength 査読有り

Zengbin Wang, Tomonori Iizuka, Masahiro Kozako, Yoshimichi Ohki and Toshikatsu Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 18 ( 6 ) 1973 - 1983 2011年12月

Development of Epoxy/BN Composites with High Thermal Conductivity and Sufficient Dielectric Breakdown Strength, Part I -Sample preparation and Thermal conductivity 査読有り

Zengbin Wang, Tomonori Iizuka, Masahiro Kozako, Yoshimichi Ohki and Toshikatsu Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 18 ( 6 ) 1963 - 1972 2011年12月

High Thermal Conductivity Epoxy/BN Composites with Sufficient Dielectric Breakdown Strength 査読有り

T.Tanaka, Z.Wang, T.Iizuka, M.Kozako, Y.Ohki

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2012) ( 7A-11 ) 691 - 694 2011年10月

Comparison of Effects of Nanofiller Materials on the Dielectric Properties of Epoxy Nanocomposites 査読有り

J.Katayama, N.Fuse, M.Kozako, T.Tanaka, Y.Ohki

2011 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2012) ( 3B-5 ) 318 - 321 2011年10月

Study on Time Lag of Void Discharge in Epoxy Resin by Considering Attenuation of X-ray Irradiation Dose 査読有り

M.Hayashi, H.Takada, M.Kozako, M.Hikita, S.Nakamura, T.Umemura, M.Higashiyama

2011 International Symposium on Electrical Insulating Materials (ISEIM2011) ( MVP2-20 ) 405 - 408 2011年09月

Development of Partial Discharge Location System in Oil-Filled Transformer Considering Acoustic Wave Propagation Properties 査読有り

H.Murayama, T.Katayama, K.Yamada, M.Kozako, M.Hikita, K.Kashine, I.Nakamura, H.Koide

2011 International Symposium on Electrical Insulating Materials (ISEIM2011) ( MVP1-13 ) 273 - 276 2011年09月

Quantitative Evaluation of Nano-silica Dispersion in Silicone Nanocomposites and Its Resistance to Erosion and Tracking 査読有り

T.Tominaga, M.Kozako, M.Hikita, R.Inoue, T.Kondo, G.Ueta, S.Okabe

2011 International Symposium on Electrical Insulating Materials (ISEIM2011) ( MVP1-20 ) 301 - 304 2011年09月

Coating of Carbon Nano-tube Filled Epoxy Resin and Its Surface Conductivity 査読有り

H.Nakatsu, M.Kozako, H.Toda, H.Ebihara, K.Yoshinaga, M.Hikita, D.Hirata, T.Miyamoto, M.Takei

2011 International Symposium on Electrical Insulating Materials (ISEIM2011) ( MVP2-6 ) 349 - 352 2011年09月

Development and Evaluation of Small Loop Sensor for Detecting Electromagnetic Field Caused by Partial Discharges in Simulated Insulation System of Inverter-fed Rotating Machine 査読有り

Y.Kudo, N.Yahara, M.Fujimoto, M.Kozako, M.Hikita

2011 International Symposium on Electrical Insulating Materials (ISEIM2011) ( MVP1-11 ) 265 - 268 2011年09月

エポキシモールド絶縁システム中の人工ボイド内部分放電現象の検討査読有り

髙田　一, 林　昌幸, 小迫雅裕, 匹田政幸, 中村修平, 梅村時博, 中村勇介, 広瀬達也, 東山雅一

電気学会論文誌A 131 ( 9 ) 785 - 791 2011年09月

Propagation Property of Partial Discharge Induced Electromagnetic Wave in Power Transformer and Comparison of UHF Sensor Characteristics 査読有り

N.Morita, M.Kozako, M.Hikita, M.Uchiyama, S.Yamada, Y.Tagniguchi

17th International Symposium on High Voltage Engineering (ISH) ( F-008 ) 4 pages 2011年08月

Influence of the Existence of the Epoxy Spacer on the Propagation Property of Partial Discharge Induced Electromagnetic Wave in Straight 154kV 査読有り

U.Khayam, M.Hayashi, M.Kozako, M.Hikita, T.Hoshino, S.Maruyama, T.Sakakibara, J.Wada, S.Okabe

17th International Symposium on High Voltage Engineering (ISH) ( F-026 ) 2011年08月

Preparation and Evaluation of Epoxy/Alumina Composite Materials toward High Thermal Conductivity 査読有り

S.Kinoshita, Y.Okazaki, M.Kozako, M.Hikita, T.Tanaka

The International Conference on Electrical Engineering 2011(ICEE2011) ( A491 ) 4 pages 2011年07月

Development of Compact Evaluation Apparatus for Power Electronics Devices under High Temperature and High Voltage Environment 査読有り

H.Kawano, M.Kozako, I.Omura, M.Hikita, T.Lebey

The International Conference on Electrical Engineering 2011(ICEE2011) ( A510 ) 4 pages 2011年07月

Measuring SiC-MOSFET Inverter Waveform and Efficiency 査読有り

S.Machino, M.Kozako, K,Harada, M.Hikita

The International Conference on Electrical Engineering 2011(ICEE2011) ( A511 ) 4 pages 2011年07月

Toward High Thermal Conductivity Nano Micro Epoxy Composites with Sufficient Endurance Voltage 査読有り

T.Tanaka, M.Kozako, K.Okamoto

2011 International Conference on Electrical Engineering and Informatics (ICEEI2011) ( A032 ) 2011年07月

モールド絶縁における微小空気ギャップの絶縁特性査読有り

東山雅一, 鈴木勇人, 広瀬達也, 中村勇介, 前田照彦, 中村修平, 梅村時博, 小迫雅裕, 匹田政幸

電気学会論文誌B Vol.131 ( No.7 ) 630 - 636 2011年07月

X-ray Irradiation Induced Discharge of Spherical Void in Epoxy Resin 査読有り

M.Hikita, M.Kozako, H.Takada, M.Higashiyama, T.Hirose, Y.Nakamura, S.Nakamura, T.Umemura

2011 Electrical Insulation Conference (EIC2011) ( No.096 S12–ML5 ) 463 - 467 2011年06月

Effect of Epoxy Spacer on Transmission Rate of Electromagnetic Wave Propagating through T-Branch of GIS Model Tank 査読有り

U.Khayam,H.Takada,M.Hayashi,S.Yoshida,T.Hoshino,T.Sakakibara,S.Maruyama,S.Okabe,J.Wada,M.Kozako,M.Hikita

7th International Workshop on High Voltage Engineering (IWHV2010) ( ED-10-87 SP-10-54 HV-10-49 ) 127 - 132 2010年11月

Propagation Properties of Electromagnetic Waves Emitted by Partial Discharge in Oil for Model Transformer Tank with a Practical Coil 査読有り

M.Kozako,A.Morita,S.Ohtsuka,M.Hikita,S.Yamada,Y.Taniguchi

International Conference on Condition Monitoring and Diagnosis (CMD2010) ( A4-3 ) 123 - 126 2010年09月

Dissolved Gas Analysis of Transformer Oil under the Conditions of Partial Discharge and Overheating 査読有り

Y.Abe,M.Kozako,H.Toda,M.Tsuchie,M.Hikita,E.Sasaki

International Conference on Condition Monitoring and Diagnosis (CMD2010) ( A4-5 ) 131 - 134 2010年09月

Development of PD Location System of Power Cable Incorporating PD Charge Distribution Measurement by Utilizing GPS and Atomic Clocks 査読有り

T.Katayama,M.Kozako,M.Hikita,K.Abe,H.Suzuki

International Conference on Condition Monitoring and Diagnosis (CMD2010) ( B1-2 ) 255 - 258 2010年09月

Partial-discharge Recognition in Three-Phase GIS using Neural Network 査読有り

D.Hamdani,U.Khayam,Suwarno,M.Kozako,M.Hikita,N.Otaka,Y.Takehara

International Conference on Condition Monitoring and Diagnosis (CMD2010) ( C1-1 ) 455 - 458 2010年09月

Influence of Different Diameter Bus Conductor Part of GIS on Propagation Property of PD-Induced Electromagnetic Wave 招待有り査読有り

M.Hikita, Y.Yamamura, M.Kozako, M.Hayashi, S.Ohtsuka, T.Hoshino, S.Maruyama, T.Sakakibara

International Conference on Condition Monitoring and Diagnosis (CMD2010) ( C2-1 ) 477 - 480 2010年09月

Switching Characteristics of SiC-VJFET and Manufacture of Inverter 査読有り

K.Harada,K.Maki,S.Pounyakhet,J.Tokiyoshi,M.Kozako,S.Ohtsuka,M.Hikita

The 2010 International Power Electronics Conference ECCE ASIA- (IPEC-Sapporo 2010) ( 22P2-23 ) 176 - 179 2010年07月

High Temperature High Voltage Packaging of Wideband Gap Semiconductors 査読有り

T.Lebey,I.Omura,M.Kozako,H.Kawano,M.Hikita

The 2010 International Power Electronics Conference ECCE ASIA- (IPEC-Sapporo 2010) ( 22P2-24 ) 180 - 186 2010年07月

Effects of Addition of Nano-scale Alumina and Silica Fillers on Thermal Conductivity and Dielectric Strength of Epoxy / Alumina Microcomposites 査読有り

Y.Okazaki,M.Kozako,M.Hikita,T.Tanaka

2010 IEEE International Conference on Solid Dielectrics (ICSD2010) ( B2-28 ) 279 - 282 2010年07月

Preparation and Evaluation of Epoxy Composite Insulating Materials toward High Thermal Conductivity 査読有り

M.Kozako,Y.Okazaki,M.Hikita,T.Tanaka

2010 IEEE International Conference on Solid Dielectrics (ICSD2010) ( F2-22 ) 2010年07月

Breakdown Voltage of Interelectrode Gap between Sphere-plane Electrodes under AC Voltage 査読有り

M.Higashiyama,T.Hirose,T.hayama,S.Nakamura,T.Umemura,M.Hikita,M.Kozako

2010 IEEE International Symposium on Electrical Insulation (ISEI2010) ( 44 ) 2010年06月

Partial Discharge Phenomena in Artificial Cavity in Epoxy Cast Resin Insulation System 査読有り

M.Hikita,M.Kozako,H.Takada,M.Higashiyama,T.Hirose,S.Nakamura,T.Umemura

2010 IEEE International Symposium on Electrical Insulation (ISEI2010) ( 138 ) 2010年06月

Research for Switching Phenomena in University 査読有り

K.Harada, H.Toda, M.kozako, S.Ohtsuka, M.Hikita, H.Ikeda

IEEJ-EIT Joint symposium advanced Technology inpower Systems ( SA-09-113 SP-09-095 FTE-09-050 PE-09-211 HV-09-104 PSE-09-219 ) 2009年11月

Low Temperature Operation of Self-recovering Micro Fuse in Liquid Nitrogen and its ON Resistance Properties 査読有り

S.Mitarai,N.Sugitani,M.Kozako,M.Hikita,S.Ohtsuka

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 346 - 349 2009年11月

Identification of Propagation Path of Acoustic Wave Signals in Simulated Transformer using Wavelet Analysis 査読有り

K.Yamada,A.Morita,M.Kozako,S.Ohtsuka,M.Hikita,K.Kashine,I.Nakamura,H.Koide

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 79 - 82 2009年11月

Corona Inception Electric Field of Arcing Horn Model by Electric Field Calculation Based On 2D and 3D Models 査読有り

H.Shirai,N.Touamoua,M.kozako,M.Hikita,M.Uehara,Y.Tsuji,S.Ohtsuka

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 126 - 199 2009年11月

Development of Partial Discharge Location System of Power Cable Using GPS and Atomic Clock 査読有り

T.Katayama,M.Kozako,S.Ohtsuka,M.Hikita,K.Abe,H.Suzuki

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 268 - 271 2009年11月

Gas Pressure Dependence of Negative Lightning Impulse PD Properties in SF6 Gas Observed by Time and Spatial-resolved Spectroscopic Measurement System 査読有り

Y.Suzuki,T.Hara,M.Fukuhara,A.Sogabe,M.Kozako,M.Hikita,S.Ohtsuka

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 276 - 279 2009年11月

Propagation Properties of PD-induced Electromagnetic Wave in Model 66kV GIS with T-Branch Structure 査読有り

Y.Yamamura,T.Nakano,S.Ohtsuka,M.Kozako,M.Hikita,T.Hoshino,S.Maruyama,T.Sakakigara,G.Ueta,S.Okabe

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 292 - 295 2009年11月

Electromagnetic Wave Propagation Characteristics Emitted from Partial Discharge by Needle-Plane Electrode in Transformer Tank Model with Practical Coil 査読有り

A.Morita,K.Yamada,Y.Abe,M.Kozako,S.Ohtsuka,M.Hikita,S.Yamada,Y.Taniguchi

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 296 - 299 2009年11月

Comparsopn of Partial Dischrge Quantity Between Tio2Filler Filled and SiO2 Filler Filled Enameled Wired Under High-frequency AC Voltage　Simulating Inverter Surge Voltage 査読有り

K.Yamaguchi,M.Fujimoto,M.Kozako,S.Ohtsuka,M.Hikita,M.Ohya,K.Tomizawa,N.Fushimi

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 300 - 303 2009年11月

Preparation and Fundamental Investigation of Characteristics of Silicon Rubber Nanocomposite for Outdoor Insulation 査読有り

M.Higashikoji,M.Kozako,S.Ohtsuka,M.Hikita,T.Tanaka

2009 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 342 - 345 2009年11月

Partial Discharge Endurance Test on Several Kinds of Nano-Filled Enameled Wires Under High-Frequency AC Voltage Simulating Inverter Surge Voltage 査読有り

M.Hikita,K.Yamaguchi,M.Fujimoto,M.Kozako,S.Ohtsuka,M.Ohya,K.Tomizawa,N.Fushimi

2009 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP2009) ( 304 ) 2009年10月

Electromagnetic Wave Propagation Characteristics Emitted from Air PD Caused by Simulated PD Source in Transformer Tank Model with Practical Coil 査読有り

M.Hikita,A.Morita,M.Kozako,S.Ohtsuka,S.Yamada,Y.Taniguchi

16th International Symposium on High Voltage Engineering (ISH) ( C-7 ) 2009年08月

Influence of a Disconnecting Part on Propagation Properties of PD-Induced Electromagnetic Wave in Model GIS 査読有り

S.Ohtsuka,H.Ikeda,M.Hikita,T.Nakano,K.Omori,M.Sawada,Y.Yamamura,M.Kozako,T.Hoshino,S.Maruyama,T.Sakakibara,G.Ueta,S.Okabe

16th International Symposium on High Voltage Engineering (ISH) ( D-52 ) 2009年08月

Influence of External Noises on Insulation Diagnosis of GIS When UHF PD Detection Method is Used 査読有り

M.Hikita,T.Nakano,K.Omori,M.Sawada,S.Ohtsuka,M.Kozako,H.Ikeda,H.Koyama,T.Hoshino,S.Maruyama,Y.Taniguchi,T.Sakakibara

16th International Symposium on High Voltage Engineering (ISH) ( A-40 ) 2009年08月

Influence of T-Branch Structure of Model GIS on Propagation Properties of PD-Induced Electromagnetic Wave 査読有り

T.Nakano,K.Omori,M.Sawada,Y.Yamamura,S.Ohtsuka,M.Kozako,H.Ikeda,M.Hikita,T.Hoshino,S.Maruyama,T.Sakakibara,G.Ueta,S.Okabe

16th International Symposium on High Voltage Engineering (ISH) ( D-49 ) 2009年08月

Fundamental study on Partial Discharge Induced Acoustic Wave　Propagation in Simulated Transformer Composite Insulation System 査読有り

M.Kozako,K.Yamada,A.Morita,S.Ohtsuka,M.Hikita,K.Kashine,I.Nakamura,H.Koide

The 9th International Conference on Properties and Applications of Dielectric Materials(ICPADM2009) ( E-19 ) 477 - 480 2009年07月

University Approach for Circuit Breaker Development 査読有り

H.Ikeda,K.Harada,S.Ohtsuka,M.Kozako,M.Hikita

20th International Conference on Electricity Distribution(CIRED2009) ( 0794 ) 2008年06月

Possible mechanisms of superior resistance of polyamide nanocomposites to partial discharges and plasmas 査読有り

N.Fuse, Y. Ohki, M. Kozako, T. Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 15 ( 1 ) 161 - 169 2008年01月

いくつかの生分解性高分子の部分放電劣化査読有り

布施則一、藤田慎二郎、平井直志、田中祀捷、小迫雅裕、向當政典、岡部成光、大木義路

電気学会論文誌A 127 ( 2 ) 389 - 396 2007年08月

ラム波解析に基づいたGIS 内自由金属異物の位置標定システムの構築査読有り

小迫雅裕,大塚信也,金子周平,岡部成光,匹田政幸

電気学会論文誌Ｂ 127 ( 2 ) 389 - 396 2007年02月

Preparation and Various Characteristics of Epoxy/ Alumina Nanocomposites 査読有り

M.Kozako,Y.Ohki,M.Kohtoh,S.Okabe,T.Tanaka

電気学会論文誌A 126 ( 11 ) 1121 - 1127 2006年11月

Treeing Phenomena in Epoxy/Alumina Nanocomposite and Interpretation by a Multi-core Model 査読有り

T.Tanaka、 A.Matsunawa、 Y.Ohki、 M.Kozako、 M.Kohtoh and S.Okabe

電気学会論文誌A 126 ( 11 ) 1128 - 1135 2006年11月

Approach by Nano- and Micro-filler Mixture toward Epoxy Based Nanocomposites as Industrial Insulating Materials 査読有り

T.Imai、 F.Sawa、 T.Ozaki、 T.Shimizu、 S.Kuge、 M.Kozako and T.Tanaka

電気学会論文誌A 126 ( 11 ) 1136 - 1143 2006年11月

Influence of Temperature on Mechanical and Insulation Properties of Epoxy-Layered Silicates Nanocomposite 査読有り

T.Imai、 F.Sawa、 T.Ozaki、 T.Shimizu、 R.Kido、 M.Kozako and T.Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 13 ( 2 ) 445 - 452 2006年02月

Effects of Epoxy/Filler Interface on Properties of Nano- or Micro-composites 査読有り

T.Imai、 F.Sawa、 T.Ozaki、 T.Shimizu、 S.Kuge、 M.Kozako and T.Tanaka

電気学会論文誌A 126 ( 2 ) 84 - 91 2006年02月

Effects of Nano- and Micro-Filler Mixture on Electrical Insulation Properties of Epoxy Based Composites 査読有り

T.Imai、 F.Sawa、 T.Nakano、 T.Ozaki、 T.Shimizu、 M.Kozako and T.Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 13 ( 2 ) 319 - 326 2006年02月

Proposal of a Multi-core Model for Polymer Nanocomposite Dielectrics 査読有り

T.Tanaka、 M.Kozako、 N.Fuse and Y.Ohki

IEEE Transactions on Dielectrics and Electrical Insulation 12 ( 4 ) 669 - 681 2005年04月

画期的な絶縁特性の向上が期待される高分子ナノコンポジット

小迫雅裕、田中祀捷

放電学会誌 ( 放電学会 ) 47 ( 4 ) 1 - 4 2004年11月

Surface Degradation of Polyamide Nanocomposites Caused by Partial Discharges Using IEC (b) Electrodes 査読有り

M.Kozako, N.Fuse, Y.Ohki, T.Okamoto and T.Tanaka

IEEE Transactions on Dielectrics and Electrical Insulation 11 ( 5 ) 833 - 839 2004年05月

超音波伝搬特性を考慮したGIS内自由金属異物の挙動およびサイズ評価査読有り

尾野本道雄、國武義高、大塚信也、小迫雅裕、湯浅禎之、岡部成光、匹田政幸

電気学会論文誌Ｂ 123 ( 11 ) 1387 - 1393 2003年11月

Motion Analysis and Size Estimation of a Free Moving Metallic Particle in GIS based on Propagation Properties of Acoustic Wave 査読有り

M.Hikita,M.Onomoto,Y.Kunitake,M.Kozako,S.Yuasa,S.Okabe,S.Ohtsuka

13th International Symposium on High Voltage Engineering (ISH) 2003年08月

UHF法で測定された電磁波第一波の振幅比に基づくGIS絶縁異常の診断査読有り

大塚信也、竹中賢司、小迫雅裕、趙孟佑、松久高士、匹田政幸

電気学会論文誌Ｂ 122 ( 6 ) 769 - 775 2002年06月

GIS内の部分放電およびフリー異物により発生するラム波の時間周波数解析査読有り

小迫雅裕、大塚信也、松久高士、匹田政幸

電気学会論文誌B 122 ( 6 ) 719 - 724 2002年06月

Time-Frequency Analysis of Lamb Waves using Wavelet Transform for Location Identification of Defects in GIS 査読有り

M.Kozako, S.Ohtsuka, K.Sawai, M.Hikita

2001 International Symposium on High Voltage Engineering (ISH) 6 ( 52 ) 991 - 994 2001年08月

GIS中の超音波伝搬特性とそれに基づく新しい部分放電発生位置標定査読有り

小迫雅裕，大塚信也，澤井浩司，匹田政幸

電気学会論文誌B 121 ( 5 ) 677 - 682 2001年05月

Risk Assessment of GIS based on Amplitude Ratio of PD-induced Electromagnetic Wave Measured by UHF Method 査読有り

K.Takenaka,M.Kozako,S.Ohtsuka,M.Cho,K.Sawai,M.Hikita

International Workshop on High Voltage Engineering (IWHV2000) 1 ( ED-00-139 ) 111 - 116 2000年11月

Identification of Partial Discharge Location based on Propagation Properties of Acoustic Waves in GIS 査読有り

M.Kozako,S.Ohtsuka,K.Sawai,M.Hikita

International Workshop on High Voltage Engineering (IWHV2000) 1 ( ED-00-137 ) 99 - 104 2000年11月

ディジタルフィルタを用いた部分放電放射電磁波からの連続周期的ノイズの除去査読有り

小迫雅裕，田志海，大塚信也，柴田信之，匹田政幸

電気学会論文誌B 120 ( 7 ) 975 - 981 2000年07月

Identification of Partial Discharge Location in Consideration of Propagation Properties of Acoustic Waves in GIS 査読有り

M.Kozako,G.F.Xiang,S.Ohtsuka,H.Suzuki,M.Hikita

2000 International High Voltage Workshop 2000年04月

Reduction of Continuous and Pulse-shape Noise by Digital Signal Proceeding for Reliable PD Detection in HV Substations 査読有り

M.Kozako, Z.H.Tian, N.Shibata, M.Hikita

11th International Symposium on High Voltage Engineering (ISH) 5 168 - 171 1999年08月

Partial Discharge Measurements and Assessment of SF6 GIS by Acoustic and Electrical Techniques 査読有り

Z.H.Tian, M.Kozako, G.F.Xiang, N.Shibata, M.Hikita

1998 Korea-Japan Joint Symposium on Electrical Discharge and High Voltage Engineering 49 - 52 1998年10月

Noise Reduction and PD Measurements using Digital Filter and Signal Processing Technique in HV Substations 査読有り

M.Kozako, Z.H.Tian, H.Okubo, N.Shibata, M.Hikita

1998 International Symposium on Electrical Insulating Materials (ISEIM) ( E2-2 ) 561 - 564 1998年09月

Application of Digital Signal Processing to Noise Reduction of Partial Discharge Detection in SF6 Gas 査読有り

M.Kozako, H.Okubo, N.Shibata, M.Hikita

1997 Japan-Korea Joint Symposium on Electrical Discharge and High Voltage Engineering 63 - 66 1997年10月

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