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Home > Undergraduate and Graduate Schools > Faculty Members List > Department of Electrical and Electronic Information Engineering > Tomohiro Kawashima

Tomohiro Kawashima

Affiliation Department of Electrical and Electronic Information Engineering
Title Assistant Professor
Fields of Research Electrical insulation, Measurement
Degree Doctor of Engineering (Toyohashi University of Technology)
Academic Societies Department of Electrical and Electronic Information Engineering
E-mail kawashima@ee
Please append ".tut.ac.jp" to the end of the address above.
Laboratory website URL http://dei.ee.tut.ac.jp/
Researcher information URL(researchmap) Researcher information

Research

Electrical insulation technique is a fundamental technology for the stable and highly efficient supply of electrical energy. In this research, based on measurement and evaluation techniques for electrical insulating materials in high electric field, we aim to develop the technologies for transporting and utilizing the generated power with high efficiency, and for condition monitoring and diagnosing of power equipment.

Theme1:Improvement of the electrical insulation systems of superconducting equipment

Overview

Superconducting technology can be supplied the electrical energy with highly efficient due to dramatically reduce electrical losses. Refrigerants are also essential for the stable maintenance of the superconducting state and they often play the role of electrical insulation at the same time. Liquid helium has been adopted as the main refrigerant, but serious shortages and rising prices continue. The future supply of liquid helium is also unclear. In addition, the discovery of high temperature superconductivity has made it possible to use liquid nitrogen, but the cooling performance is low because the temperature range available cooling by taking advantage of sensible heat is narrow and the heat capacity is small. Slash nitrogen is a mixed refrigerant of liquid nitrogen and solid nitrogen particles. It has been well known that slush nitrogen has higher performances in cooling than liquid nitrogen due to solid nitrogen having high melting latent heat. It is also expected that slush nitrogen has also higher electrical insulation performance because the energy of partial discharge can be consumed by melting solid nitrogen particles. In this research, we aim to clarify the electrical insulation performance of slush nitrogen by the evaluation based on the discharge mechanism.

Keywords

Cryogenic electrical insulation, Slush nitrogen, Liquid nitrogen, Breakdown, Partial discharge

Theme2:Development of measurement and evaluation technology for partial discharge phenomenon

Overview

Partial discharge is a precursory phenomenon to breakdown and does not immediately lead to breakdown. However, it is important to prevent the breakdown by measuring partial discharges with high sensitivity and by diagnosing the internal condition in power equipment, because the continuous occurrence of the partial discharges cause the electrical degradation of the insulating material. In addition, in order to determine the ratio of degradation, it is also necessary to understand the difference of generation mechanism of partial discharges depending on the surface shape of the insulating material, contamination, surface charges and so on. In this research, we aim to develop measurement and evaluation technologies that can be analyzed various partial discharge phenomena quantitatively.

Keywords

Waveform of partial discharge, Surface charge, Surface resistivity

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