Faculty Profiles - KOJIMA Hiroki

Presentations -

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

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

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

Event date： 2016.10

Language：English Presentation type：Poster presentation

Venue：Toronto Country：Canada

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

DOI： 10.1109/CEIDP.2016.7785622

Scopus

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

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

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

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

Event date： 2016.10

Language：English Presentation type：Poster presentation

Venue：Toronto Country：Canada

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

DOI： 10.1109/CEIDP.2016.7785621

Scopus

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

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

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

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

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

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

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

Event date： 2016.9

Language：English Presentation type：Oral presentation (general)

Venue：Suzhou Country：China

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

DOI： 10.1109/DEIV.2016.7748662

Scopus

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

UHF法における部分放電電流波形と電磁波強度との相関

加藤拓，小島寛樹，早川直樹

平成28年度電気・電子・情報関係学会東海支部連合大会