EP0795877B1 - DC bushing - Google Patents

DC bushing Download PDF

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Publication number
EP0795877B1
EP0795877B1 EP19970103464 EP97103464A EP0795877B1 EP 0795877 B1 EP0795877 B1 EP 0795877B1 EP 19970103464 EP19970103464 EP 19970103464 EP 97103464 A EP97103464 A EP 97103464A EP 0795877 B1 EP0795877 B1 EP 0795877B1
Authority
EP
European Patent Office
Prior art keywords
shield
bushing
oil
barrier
voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Revoked
Application number
EP19970103464
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0795877A3 (en
EP0795877A2 (en
Inventor
Masaru Kashiwakura
Kazuo Sekine
Toshimitsu Obata
Hiroaki Kojima
Makoto Tanaka
Hiroshi Sugihara
Masayuki Hatano
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electric Power Development Co Ltd
Kansai Electric Power Co Inc
Shikoku Electric Power Co Inc
Hitachi Ltd
Original Assignee
Electric Power Development Co Ltd
Kansai Electric Power Co Inc
Shikoku Electric Power Co Inc
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
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Application filed by Electric Power Development Co Ltd, Kansai Electric Power Co Inc, Shikoku Electric Power Co Inc, Hitachi Ltd filed Critical Electric Power Development Co Ltd
Publication of EP0795877A2 publication Critical patent/EP0795877A2/en
Publication of EP0795877A3 publication Critical patent/EP0795877A3/en
Application granted granted Critical
Publication of EP0795877B1 publication Critical patent/EP0795877B1/en
Anticipated expiration legal-status Critical
Revoked legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B17/00—Insulators or insulating bodies characterised by their form
    • H01B17/26—Lead-in insulators; Lead-through insulators
    • H01B17/28—Capacitor type

Definitions

  • the present invention relates generally to a DC bushing employed in an electric power transmission system. More particularly, the invention is concerned with an improved structure of a DC bushing equipped with a shield barrier enclosing a lower insulated shield disposed at a lower portion of the DC bushing.
  • DC-500 kV transmission system structurization of a DC transmission system rated 500 kV (hereinafter also referred to as the DC-500 kV transmission system) is being planned.
  • DC bushings for DC apparatuses and machines are indispensable.
  • FIG. 1 of the accompanying drawings shows a DC bushing in the state mounted in transformer equipment.
  • a transformer 20 composed of a core 21 and a coil 22 is disposed within a tank 11 which is filled with an insulating oil 23.
  • a DC bushing 24 is employed for insulating an output or input line of the transformer 20 from the tank 11.
  • Fig. 2 shows an insulation structure disclosed in JP-A-56-81909.
  • a porcelain tube 1 supported in a tank 11 filled with insulating oil is provided with a barrier 6 at a lower portion of the porcelain tube 1, the barrier 6 being formed by oil-impregnated paper, wherein a shielding electrode 3 which is so disposed as to enclose a metal flange 10 mounted at a bottom end of the porcelain tube 1 is covered with an insulating cover or layer 4 formed of oil-impregnated paper to realize a lower insulated shield 5.
  • a mineral oil is used as the insulating oil, while the solid insulator is formed of kraft paper or pressboard impregnated with mineral oil.
  • volume resistivity of the mineral oil is lower than that of the oil-impregnated paper by one order of magnitude. Consequently, when a DC voltage is applied, a major proportion of the voltage will be borne by the oil-impregnated paper forming the insulating cover 4 of the lower insulated shield 5, resulting in that the electric field which is higher by one order of the electric field appearing in the oil gap 7 acts on the oil-impregnated paper layer.
  • the electric field appearing at an upper end portion of the lower insulated shield 5 immersed in the oil exhibits highest intensity.
  • the insulation certainly can be ensured for the DC voltage of 250 kV with the structure of the conventional DC bushing described above.
  • dielectric breakdown may take place, starting from the upper end portion of the lower insulated shield 5.
  • the invention is directed to a DC bushing which is comprised of a porcelain tube constituting a lower portion of the DC bushing and immersed in an insulating oil contained in a tank, a lower insulated shield provided at a lower end portion of the porcelain tube and including a shielding electrode covered with an insulating cover, and a shield barrier disposed around an outer periphery of the lower insulated shield with an oil gap being defined between the shield barrier and the lower insulated shield.
  • the shield barrier by using a solid insulator which exhibits a higher volume resistivity than that of the oil-impregnated paper.
  • the shield barrier has a structure that upon application of a DC voltage, a proportion of the DC voltage to be borne by the shield barrier is larger than 15 % inclusive.
  • Figure 3 is a sectional view showing a DC bushing which is designed for use in an electric power transmission system rated DC 500 kV according to an exemplary embodiment of the invention.
  • a DC bushing 24 is fixedly mounted in a tank 11 which is filled with an insulating oil, wherein a conductor 2 is secured to a bottom portion of a porcelain tube 1 of the DC bushing 24 by using a metal flange 10.
  • a lower insulated shield 5 is provided in such disposition that outer peripheral portions of the metal flange 10 and the conductor 2 are enclosed by the lower insulated shield 5.
  • the lower insulated shield 5 is composed of a shielding electrode 3 and an insulating cover 4 formed by winding oil-impregnated crepe paper around the shielding electrode 3.
  • a barrier 6 formed of crepe paper is mounted at a lower portion of the porcelain tube 1 in such disposition as to close a gap formed between the porcelain tube 1 and the lower insulated shield 5.
  • a shield barrier 8 made of oil-impregnated paper and serving as a solid insulator is so disposed as to cover a lower end portion of the barrier 6 and an outer peripheral portion of the lower insulated shield 5, wherein an oil gap is defined between the shield barrier 8 and the lower insulated shield 5 for allowing the insulating oil to move through the oil gap 7.
  • Figure 5 is a fragmentary enlarged sectional view showing a major portion of the DC bushing together with a map of electric field which makes appearance in a top end portion of the lower insulated shield 5 and the shield barrier 8 disposed in opposition to the lower insulated shield 5, when a DC voltage of 500 kV is applied to the conductor 2.
  • the shield barrier 8 has a thickness W2 which is greater than a width W1 of the oil gap 7 defined between the lower insulated shield 5 and the shield barrier 8 disposed in opposition to the lower insulated shield 5, as viewed in the direction widthwise of the oil gap 7.
  • Fig. 4 shows a map of electric field making appearance in the conventional DC bushing shown in Fig. 2.
  • the thickness W3 of the shield barrier 8 is smaller than the width W1 of the oil gap 7 defined between the lower insulated shield 5 and the shield barrier 8 for some reasons from the standpoint of manufacturing.
  • the shield barrier 8 is provided intrinsically for the purpose of preventing the dielectric breakdown which may occur, starting from the lower insulated shield 5 and the conductor 2, and it has heretofore been believed that there is no necessity of increasing the thickness of the shield barrier 8 because of higher intensity of the electric field in the solid insulator as viewed in the direction perpendicularly to the layers of the solid insulator.
  • the thickness W2 of the shield barrier 8 is increased, as described above, a portion of the voltage which is to be borne by the barrier 6 in the case of the conventional DC bushing (see Fig. 4) is transferred to the shield barrier 8, as can be seen from Fig. 5, as a result of which the intensity of the electric field internally of the barrier 6 and the insulating cover 4 is correspondingly mitigated, whereby the dielectric strength of the DC bushing as a whole can be enhanced.
  • Figure 6 is a sectional view showing a DC bushing designed for use in a DC-500-kV transmission system according to another embodiment of the invention.
  • the DC bushing shown in Fig. 6 differs from the structure shown in Fig. 3 in respect to the material and the thickness of the shield barrier. More specifically, in the DC bushing according to the instant embodiment of the invention now under consideration, the shield barrier designated by reference numeral 9 is formed of a solid insulator having a higher volume resistivity than that of the oil-impregnated paper with the thickness of the shield barrier 9 being held substantially same as that of the shield barrier 8 employed in the conventional DC bushing. Except for these differences, the DC bushing according to the instant embodiment of the invention is substantially same as the conventional one. Accordingly, components same as or equivalent to those of the DC bushing shown in Fig. 3 are designated by like reference characters and repeated description thereof is omitted.
  • the insulating cover 4 is formed of oil-impregnated paper such as kraft paper, pressboard or the like which has a volume resistivity ranging from of 10 15 to 10 16 ⁇ cm.
  • the shield barrier 9 is formed of an insulation material having the volume resistivity which is higher than that of the oil-impregnated paper by one order of magnitude.
  • the preferred insulation material for forming the shield barrier 9 there may be mentioned engineering plastic materials such as, for example, PET (polyethylene terephthalate), PTFE (polytetrafluoride ethylene), PPO (polyphenylene oxide), PPS (polyphenylene sulfide), PMP (polymethyle pentene), PE (polyethylene) and the like.
  • the shield barrier 9 may be formed by molding a sheet of the material mentioned above or by winding a film of the material mentioned above. The materials enumerated above have specific inductive capacities falling within a range of "2" to "3".
  • the dielectric constant of these materials is lower than that of the oil-impregnated paper and can not give rise to concentration of the electric field in the oil gap even when an AC voltage is applied to the conductor 2.
  • the materials mentioned above is preferred for forming the shield barrier 9.
  • the proportion of the voltage borne by the shield barrier 9 upon application of DC voltage to the conductor 2 is greater than that to be borne by the shield barrier of the conventional DC bushing.
  • the intensity of the electric field appearing in the insulating cover 4 can be mitigated, whereby the DC dielectric strength of the DC bushing can be improved with the reliability thereof being enhanced.
  • the thickness W3 of the shield barrier 8 is selected to be greater than the width W1 of the oil gap 7 formed between the shield barrier 8 and the lower insulated shield 5, while in the DC bushing shown in Fig. 6, the shield barrier 9 is formed of a solid insulator having a higher volume resistivity than that of the oil-impregnated paper, to thereby realize reduction of the proportion of voltage to be borne by the insulating cover 4.
  • the thickness and/or material of the shield barrier may be determined reversely on the basis of predetermined proportion of voltage to be borne by the shield barrier.
  • the shield barrier 8 is formed of oil-impregnated paper.
  • the insulation material of high volume resistivity such as PET or the like as adopted in the DC bushing shown in Fig. 6 is employed for implementing the shield barrier 8 shown in Fig. 3, the dielectric strength can further be enhanced.
  • the proportion of the voltage to be borne by the shield barrier 8 and hence the DC dielectric strength of the DC bushing on the whole can further be increased by decreasing the width of the oil gap within a range where convection of the insulating oil for heat dissipation is not interfered.
  • the proportion of voltage to be borne by the insulating cover of the lower insulated shield can be reduced by selecting the thickness of the shield barrier to be greater than the width of the oil gap as viewed in the direction widthwise thereof and/or by forming the shield barrier of a solid insulator having a higher volume resistivity than that of oil-impregnated paper, preferably by realizing the shield barrier in such a structure that upon application of a DC voltage, the proportion of the DC voltage to be borne by the shield barrier is higher than 15 % inclusive.
  • the DC dielectric strength in the vicinity of the lower insulated shield can significantly be improved to assure high reliability of the DC bushing.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Insulators (AREA)
  • Insulating Bodies (AREA)
EP19970103464 1996-03-14 1997-03-03 DC bushing Revoked EP0795877B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP8057590A JP2771505B2 (ja) 1996-03-14 1996-03-14 直流ブッシング
JP57590/96 1996-03-14
JP5759096 1996-03-14

Publications (3)

Publication Number Publication Date
EP0795877A2 EP0795877A2 (en) 1997-09-17
EP0795877A3 EP0795877A3 (en) 1998-09-16
EP0795877B1 true EP0795877B1 (en) 2001-12-05

Family

ID=13060071

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19970103464 Revoked EP0795877B1 (en) 1996-03-14 1997-03-03 DC bushing

Country Status (4)

Country Link
EP (1) EP0795877B1 (zh)
JP (1) JP2771505B2 (zh)
CN (1) CN1075659C (zh)
DE (1) DE69708727T2 (zh)

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005021255B4 (de) * 2005-05-02 2007-08-16 Siemens Ag Barrierensystem für die Leitungsdurchführung einer elektrischen Anlage
US7994427B2 (en) 2006-03-24 2011-08-09 Abb Technology Ltd. High voltage insulation system and a method of manufacturing same
CN101136269B (zh) 2006-08-31 2013-03-27 Abb研究有限公司 高压套管
CN101373659B (zh) * 2007-08-20 2012-08-22 特变电工股份有限公司 一种电抗器线圈的出线装置及含有该出线装置的铁心电抗器
CN101373655B (zh) 2007-08-20 2013-12-04 特变电工股份有限公司 一种铁心电抗器
CN101409120B (zh) * 2008-11-20 2011-09-14 武汉市德赛电力设备有限公司 一种能提高外绝缘电气强度的绝缘子
FR2947092B1 (fr) * 2009-06-18 2016-08-26 Areva T & D Sa Structure apte a ameliorer la tenue dielectrique de composants electriques.
DE102011008459A1 (de) * 2011-01-07 2012-07-12 Siemens Aktiengesellschaft Leitungsdurchführung für die Kesselwand einer HGÜ-Komponente
DE102011008456A1 (de) * 2011-01-07 2012-07-12 Siemens Aktiengesellschaft Leitungsführung für HGÜ-Transformatorspulen oder HGÜ-Drosselspulen
DE102011008461A1 (de) * 2011-01-07 2012-07-12 Siemens Aktiengesellschaft Trennstelle einer Leitungsdurchführung für eine HGÜ-Komponente
EP2528071B1 (en) * 2011-05-27 2018-08-08 ABB Schweiz AG High voltage arrangement comprising an insulating structure
CN102682934B (zh) * 2011-12-01 2014-01-22 湖北鑫德赛绝缘技术有限公司 一种带组合式屏障的绝缘子
EP2620958B1 (de) * 2012-01-26 2014-11-26 Siemens Aktiengesellschaft Abschirmvorrichtung für ein elektrisch leitfähiges Verbindungselement
CN102543390B (zh) * 2012-02-27 2014-06-04 中国西电电气股份有限公司 一种特高压换流变压器交流750kV端部出线结构
KR101363930B1 (ko) * 2012-09-24 2014-02-19 주식회사 상원 이중망 구조의 부싱용 쉴드
CN104485210B (zh) * 2014-12-15 2016-06-22 中国西电电气股份有限公司 一种特高压换流变压器网侧750kV引出线配套结构

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55136411A (en) * 1979-04-11 1980-10-24 Tokyo Shibaura Electric Co Bushing pocket
JPS5681909A (en) * 1979-12-10 1981-07-04 Hitachi Ltd Terminal conductor connecting system
EP0285895B1 (de) * 1987-04-09 1992-03-11 Siemens Aktiengesellschaft Hochspannungsisolationsanordnung fuer Transformatoren und Drosselspulen, insbesondere zur Hochspannungs-Gleichstrom-Uebertragung (HGUE)
JPH09153314A (ja) * 1995-11-29 1997-06-10 Kansai Electric Power Co Inc:The 直流用油入ブッシング

Also Published As

Publication number Publication date
CN1075659C (zh) 2001-11-28
EP0795877A3 (en) 1998-09-16
EP0795877A2 (en) 1997-09-17
JPH09251814A (ja) 1997-09-22
DE69708727D1 (de) 2002-01-17
CN1162183A (zh) 1997-10-15
DE69708727T2 (de) 2002-08-29
JP2771505B2 (ja) 1998-07-02

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