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STUDIES ON INSULATION DESIGN OF HIGH VOLTAGE DIELECTRIC SPACERS USED IN VACUUM

Research Project

Project/Area Number 11650284
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 電力工学・電気機器工学
Research InstitutionKYOTO UNIVERSITY

Principal Investigator

YAMAMOTO Osamu  KYOTO UNIVERSITY, Dept.of Engineering, Research Associate, 工学研究科, 助手 (70093333)

Co-Investigator(Kenkyū-buntansha) HAMADA Shoji  KYOTO UNIVERSITY, Dept.of Engineering, Lecturer, 工学研究科, 講師 (20246656)
TAKUMA Tadasu  KYOTO UNIVERSITY, Dept.of Engineering, Professor, 工学研究科, 教授 (50221370)
Project Period (FY) 1999 – 2000
Project Status Completed (Fiscal Year 2000)
Budget Amount *help
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥2,700,000 (Direct Cost: ¥2,700,000)
KeywordsVacuum / surface discharge / charging / Surface roughness / insulation design / compact spacer / Spacer shape / cathode electric field / 固体材料 / スペーサ
Research Abstract

The charging of a dielectric insulator is considered to be a critical phenomenon leading bridged vacuum gaps to flashover. The goal of this study is to obtain an engineering aspect for designing the shape of spacer taking the charging phenomena into account. To investigate the charging process, we have employed an electrostatic method, which uses a small isolated part of the cathode as a probe. This probe technique enables us a real-time observation of surface charging under a ramped or stepwise DC voltage excitatin. We have also employed a simulation technique that analyzes the charge distribution on the insulator based on the secondary emission electron avalanche (SEEA) model.
First, the influence of surface roughness on the charging of an insulator in vacuum has been investigated. A cylindrical insulating spacer made of acryl resin (PMMA), Teflon (PTFE) or alumina ceramics (92% Al_2O_3) is exarnined under rarnped, or stepped DC voltage application. Each sample has a roughness ranging … More from 0.15 to 50 μm. The results exhibit that the surface roughness decisively affects the charging, which is more pronounced for more highly polished insulators. For instance, the smooth surface of a cylindrical specimen made of PMMA or alumina acquires charge several times higher than that with rough surface. The specimen made of PIFE is hard to acquire the surface charge irrespective of its surface roughness. When an insulator is subjected to a stepwise DC voltage, the probe signal shows that the charging occurs with considerable delay, ranging from 10^<-5>s up to 10 s depending on the material, the voltage height and also the surface roughness of the insulator. Two-dimensional Monte Carlo simulation based on the secondary emission electron avalanche model has been performed to analyze the progress of the charging. During the delay period, positive charge accumulates on the surface of the insulator near the cathode, which further accelerates the charging.
Second, the specimen in the shape of a conical frustum has been investigated. The spacer with a slight positive or a negative cone angle (-25゜≦α≦+2゜ ) acquires a positive charge of which density increases almost linearly with the applied voltage. The more positively angled spacer acquires no charge. These results agree with the theoretical prediction based on the SEEA mechanism. On the contrary, the spacer with a cone angle α<-25゜ acquires a localized negative charge. This result differs from the theoretical prediction in which a considerably high-density negative charge accumulates over the surface. We have shown that the progress of negative charging ceases due to the relaxation of the electric field near the cathode TJ.
These results clearly show the importance of surface treatments and the spacer shape in the insulation design. Overall results show that insulators that are hard to acquire the surface charge have very good insulation performance. Less

Report

(3 results)
  • 2000 Annual Research Report   Final Research Report Summary
  • 1999 Annual Research Report

Research Products

(14 results)

All Other

All Publications (14 results)

  • [Publications] 山本修: "真空中の固体誘電体帯電現象における表面粗さの影響響"電気学会論文誌A. 119巻. 1221-1228 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Osamu Yamamoto: "Delay characteristics of surface charging on a cylindrical Insulator in Vacuum"IEEE Trans.on Dielectrics and Electrical Insulation. Vol.7. 812-817 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] 山本修: "真空中円錐台形スペーサの帯電特性-角度依存性に関する理論と実験結果の比較-"電気学会論文誌A. 120巻. 1070-1075 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] O.Yamamoto, T.Takuma, S.Hamada et al.: "Influence of Surface Roughness on Charging of an Insulating Spacer in Vacuum"Trans.IEE of Japan. Vol.119, No.10. 1221-1228 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] O.Yamamoto, T.Takuma, S.Hamada, Y.Tanabe, Y.Kakehashi, S.Ikoma, K.Nishimura: "Delay characteristics of surface charging on a cylindrical insulator in vacuum"Proc.of the 11th Int.Symp.on High Voltage Engineering (ISH), London. No.3.341. 4 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] O.Yamamoto, T.Takuma et al.: "Delay Characteristics of Surface Charging on a Cylindrical Insulator in Vacuum"IEEE Trans.on Dielectrics and Electrical Insulation. Vol.7, No.6. 812-817 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] O.Yamamoto, T.Takuma et al.: "Charging Characteristics of a Conical Insulating Spacers in Vacuum - Comparison of measured and theoretical results on the influence of contact angle"Trans.IEE of Japan. Vol.129, No.12. 1070-1075 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] O.Yamamoto, T.Takuma et al.: "Charging characteristics of a conical insulating spacer in vacuum-comparison of measured and theoretical results-"Proc.of the 19th Int.Symp.on Discharges and Electrical Insulation in Vacuum, Xi'an. 108-112 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] O.Yamamoto, T.Takuma, Y.Kakehashi, S.Ikoma, A.Nishimoto, T.Iida: "Charging Characteristics and Dielectric Strength of a Conical Insulating Spacer in Vacuum Proc.of the 10th Asian Conf."Electrical Discharge (ACED), Kyoto. C-303 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] 山本修: "真空中の固体誘電体帯電現象における表面粗さの影響響"電気学会論文誌A. 119巻. 1221-1228 (1999)

    • Related Report
      2000 Annual Research Report
  • [Publications] Osamu Yamamoto: "Delay characteristics of surface charging on a cylindrical Insulator in Vacuum"IEEE Trans. on Dielectrics and Electrical Insulation. Vol.7. 812-817 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] 山本修: "真空中円錐台形スペーサの帯電特性-角度依存性に関する理論と実験結果の比較-"電気学会論文誌A. 120巻. 1070-1075 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] 山本 修,他: "真空中絶縁スペーサの表面粗さと帯電・フラッシオーバ特性"電気学会放電研究会資料. ED-99-187. 25-30 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] 山本 修,他: "真空中円錐台形スペーサの帯電特性"電気学会放電研究会資料. ED-99-194. 31-36 (1999)

    • Related Report
      1999 Annual Research Report

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Published: 1999-03-31   Modified: 2016-04-21  

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