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ABSTRACT: Functionally graded materials (FGM) have spatial distribution of a material property in order to achieve efficient stress control. An application of the FGM to a solid insulator (spacer) for a gaseous insulation system, like gas insulated switchgear, is expected to improve electric field (E-field) distribution around the spacer. In this paper, we describe the applicability of the FGM spacer to gas insulated power equipment. In the FGM spacer, we gave spatial distribution of dielectric permittivity to control the E-field distribution inside and outside the spacer. This paper includes following key results for the applications of the FGM. Firstly, E-field simulation results when applying the FGM by a finite element method are presented, in which we show the effective reduction of the maximum field strength by applying the FGM. Next, a fabrication technique of the FGM spacer sample with not only step-by-step but also continuous changes of permittivity is presented by use of centrifugal force. Finally, dielectric breakdown tests using FGM samples which are accurately controlled the spatial distribution of permittivity are carried out under lightning impulse voltage applications. The test result indicates the increase of breakdown voltage (BDV). From these results, we verified the applicability and the fabrication technique of FGM spacer for improvement of the dielectric strength in the gaseous insulation system.
IEEE Transactions on Dielectrics and Electrical Insulation 05/2006; · 1.09 Impact Factor
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ABSTRACT: For electrical insulation design of GIS spacer, we need to control electric field distribution around the solid spacer, especially around the triple junction (TJ). For this purpose, we proposed the application of functionally gradient materials (FGM), which has spatial distribution of dielectric permittivity, to the spacer of SF<sub>6</sub> GIS. In this paper, we discussed applicability of FGM with numerical simulation and fabrication conditions. We firstly investigated the field control effect of the FGM spacer with a conical shape, by finite element method (FEM). Secondly, we fabricated FGM spacer with continuously graded distribution of permittivity by applying the centrifugal force. As for the filler material to control the permittivity, we selected TiO<sub>2</sub> rutile crystal particle. In order to obtain the optimum permittivity distribution, centrifugal forces, their application duration, the diameter distribution of filler particles, volume ratio of filler versus resins and so on were controlled.
Properties and Applications of Dielectric Materials, 2003. Proceedings of the 7th International Conference on; 07/2003
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ABSTRACT: Functionally gradient materials (FGM) have a spatial distribution of permittivity in order to achieve an efficient stress control. The application of FGM to solid spacers for gas insulated switchgear (GIS) is expected to improve electric field distribution around the spacer. In this paper, we discussed the applicability of FGM with experimental results and fabrication conditions. We firstly investigated the field control effect of the double-layer distribution FGM spacer by dielectric breakdown experiments under the application of lightning impulse voltage. Secondly, we confirmed the effect of FGM on the enhancement of electric field utilization experimentally. Thirdly, we succeeded in the fabrication of continuously graded distribution of permittivity by applying the centrifugal force technique.
Electrical Insulation and Dielectric Phenomena, 2002 Annual Report Conference on; 02/2002
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ABSTRACT: Functionally gradient materials (FGM) have a spatial distribution of permittivity in order to achieve an efficient stress control. Application of FGM for solid spacer of electric apparatus is expected to improve electric field distribution around the spacer. This paper presents the applicability of FGM to solid spacer model in SF<sub>6</sub> gas, both by numerical simulation and breakdown experiments. The effect of FGM on the enhancement of electric field utilization is presented in this study
Electrical Insulation and Dielectric Phenomena, 2001 Annual Report. Conference on; 02/2001
