EP0780868A2 - Elektrisch leitender Schirm für einen Vakuumschalter - Google Patents

Elektrisch leitender Schirm für einen Vakuumschalter Download PDF

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Publication number
EP0780868A2
EP0780868A2 EP96308893A EP96308893A EP0780868A2 EP 0780868 A2 EP0780868 A2 EP 0780868A2 EP 96308893 A EP96308893 A EP 96308893A EP 96308893 A EP96308893 A EP 96308893A EP 0780868 A2 EP0780868 A2 EP 0780868A2
Authority
EP
European Patent Office
Prior art keywords
shield
inner element
domes
unit
lip
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.)
Granted
Application number
EP96308893A
Other languages
English (en)
French (fr)
Other versions
EP0780868A3 (de
EP0780868B1 (de
Inventor
John Rand
Leslie Thomas Falkingham
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.)
GE Power UK
Original Assignee
GEC Alsthom 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
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First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=10785861&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0780868(A2) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by GEC Alsthom Ltd filed Critical GEC Alsthom Ltd
Publication of EP0780868A2 publication Critical patent/EP0780868A2/de
Publication of EP0780868A3 publication Critical patent/EP0780868A3/de
Application granted granted Critical
Publication of EP0780868B1 publication Critical patent/EP0780868B1/de
Anticipated expiration legal-status Critical
Revoked legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/60—Switches wherein the means for extinguishing or preventing the arc do not include separate means for obtaining or increasing flow of arc-extinguishing fluid
    • H01H33/66—Vacuum switches
    • H01H33/662—Housings or protective screens
    • H01H33/66261—Specific screen details, e.g. mounting, materials, multiple screens or specific electrical field considerations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/60—Switches wherein the means for extinguishing or preventing the arc do not include separate means for obtaining or increasing flow of arc-extinguishing fluid
    • H01H33/66—Vacuum switches
    • H01H33/662—Housings or protective screens
    • H01H33/66261—Specific screen details, e.g. mounting, materials, multiple screens or specific electrical field considerations
    • H01H2033/66276—Details relating to the mounting of screens in vacuum switches

Definitions

  • the invention concerns an electrically conductive shield for a vacuum switching device, in particular a vacuum interrupter, also a unit to be assembled by brazing and a method for assembling a unit by brazing.
  • Vacuum interrupters are commonly used in electrical equipment for interrupting an AC supply in the event of a fault, e.g. a short-circuit on a power line.
  • a typical vacuum interrupter is shown in very general terms in Figure 1.
  • the interrupter comprises an insulator 10, normally a ceramic, housing two electrically conductive contacts 11, 12. Contacts 11, 12 are taken out of the interrupter unit by means of respective stems 13, 14, the sterns terminating in end-portions 15, 16 for connection to further electrical equipment (not shown).
  • the end-portions 15, 16 may have external or internal threads for effecting the connections.
  • the bellows unit 17 allows axial movement of the stem 14 to make and break, selectively, electrical contact between the contacts 11 and 12, contact 11 and stem 13 being fixed relative to the insulator 10.
  • the shield 18 is an electrically conductive component which serves two main purposes: to prevent an arc, which is drawn when the contacts are separated, from striking the insulator, and to impede the deposition of metal vapour, which is given off from the contacts when the arc is present, on the insulator.
  • an electrically conductive shield for a vacuum interrupter unit comprising means for effecting self-centering of the shield within said vacuum interrupter unit upon application of heat to said shield.
  • the shield may be substantially circular cylindrical, said means for effecting self-centering comprising three outwardly facing domes formed from said shield as dimples therein, said domes being disposed at substantially equal distances around a circumference of said shield.
  • the domes may be formed from a portion of the shield which lies substantially parallel to a longitudinal axis of the shield.
  • the shield may comprise first and second shield members, said first and second shield members each comprising means for effecting self-centering of the respective shield member within the vacuum interrupter upon application of heat to said shield.
  • Said shield members may be substantially circular cylindrical, a portion of at least said first shield member being substantially parallel to a longitudinal axis of the shield, said means for effecting self-centering of said first shield member comprising three outwardly facing domes made from said portion of said first shield member as dimples therein, said domes being disposed at substantially equal distances around a circumference of said portion, and said means for effecting self-centering in said second shield member comprising an outwardly turned lip at one end of said second shield member.
  • Said first and second shield members may have corresponding first ends to be positioned adjacent each other, said substantially parallel portion of said first shield member being disposed at the first end of said first shield member and said outwardly turned lip of said second shield member being disposed at the first end of said second shield member.
  • the first shield member may comprise an attachment means for allowing attachment of said first shield member to an insulating wall of the vacuum interrupter.
  • the attachment means may comprise a brazable, outwardly facing lip disposed at said first end of said first shield member.
  • a maximum outside diameter of said first shield member, taking into account said domes, may be substantially the same as an outside diameter of the outwardly turned lip of said second shield member.
  • the shield may be made from a soft, high-expansion material, which may be copper.
  • a vacuum switching device comprising an electrically conductive shield as described above.
  • a unit to be assembled by brazing comprising an outer, substantially circular cylindrical, housing arrangement and an inner, substantially circular cylindrical element disposed within said housing arrangement, said inner element having a higher coefficient of thermal expansion than said housing arrangement, said inner element comprising an attachment means for attaching said inner element to said housing arrangement by brazing and a means for effecting self-centering of the shield within said unit upon application of heat to said unit.
  • Said means for effecting self-centering may comprise three outwardly facing domes formed from said inner element as dimples therein, said domes being disposed at substantially equal distances around a circumference of said inner element, said inner element having when cold, and taking account of said domes, a maximum outside diameter less than an inside diameter of said housing arrangement.
  • the domes may be formed from a portion of said inner element which lies substantially parallel to a longitudinal axis of the inner element.
  • Said housing arrangement may comprise two outer, substantially circular cylindrical, concentric elements, and said attachment means may comprise a brazable, outwardly facing lip for sandwiching between said outer elements.
  • Said inner element may be composed of a softer material than said housing arrangement.
  • Said inner element may be made from copper, and said housing arrangement may be made from a ceramic.
  • said lip of said inner element may be secured by brazing between said outer elements and said domes may touch one of said outer elements and be distorted at a point of contact with said one of said outer elements.
  • a method of assembling a unit by brazing comprising two outer circular cylindrical elements of a first, internal diameter, the outer elements having brazable end faces, and an inner circular cylindrical element, said inner element having a higher coefficient of thermal expansion than, and being of a softer material than, said outer elements and comprising at one end a brazable, outwardly facing lip substantially perpendicular to a longitudinal axis of said inner element, said inner element comprising three outwardly facing domes made from said inner element as dimples therein, said domes being disposed at substantially equal distances around a circumference of said inner element, said inner element having when cold, and taking account said domes, a second, outside diameter less than said first, internal diameter, the method comprising the steps of:
  • Said unit may comprise a further circular cylindrical inner element having at one end thereof an outwardly facing lip, said lip of said further inner element having when cold a third, outside diameter less than said first, inside diameter, the method including after step (a) the step of positioning said further inner element on top of said inner element such that the lip of said further inner element touches the lip of said inner element, the method in step (b) allowing said third, outside diameter to increase until the lip of said further inner element touches one of said outer elements, and the method in step (c) allowing an end-portion of said further inner element adjacent said lip to distort in shape during said increase in temperature.
  • Said unit may be a vacuum switching device, said outer elements may be ceramic insulators and said inner elements may constitute a conductive shield.
  • a vacuum interrupter according to an aspect of the invention is illustrated comprising a pair of contacts 11, 12 on stems 13, 14 (these components being shown by dotted lines) with associated end-stubs 15, 16, two outer ceramic insulator elements 8, 9 making up an insulator housing arrangement 10, and an electrically conductive shield 18 consisting of first and second shield members 19, 20.
  • Two end-rings 23 and 24 form anchoring points for their associated stems and end-stubs relative to the ceramic insulators 8, 9.
  • the whole interrupter assembly is meant to be brazed together in one operation, and in order to maintain a central position of the shield members within the assembly, the shield members are equipped with self-centering means as shown in Figure 3.
  • Figure 3(a) shows the preferred form of the first shield member 19, which is circular cylindrical like the ceramic insulator elements and includes portions 30, 31 substantially parallel to a longitudinal axis 26 of the assembly and non--parallel, i.e. tapering, portions 32, 33.
  • the most notable feature of this shield member is the presence of small domes 33 (see also Figure 1) in the substantially parallel portion 30 of the shield.
  • Domes 33 are made from the shield wall itself and form dimple-like structures viewed from inside the shield member 19 and roughly hemispherical projections when viewed from outside the shield member.
  • the height of the domes from the wall of the shield portion 30 is such that an outside diameter 34 of the shield member is, when the assembly is cold and in an unbrazed state, slightly less than an inside diameter of the ceramic insulator elements 8, 9 and significantly less than an outside diameter 35 of a lip 36 formed in the end of the shield member 29 nearest the domes 33 (see Figure 4).
  • the lip 36 is designed to be sandwiched between brazable end-faces of the insulator elements 8, 9, and to this end the outside diameter 35 is arranged to be approximately equal to the outside diameter of the insulator elements 8, 9 (see Figure 2).
  • Figure 3(b) shows a view of the second shield member 20.
  • This member has an outwardly turned lip 40 which is approximately of the same outside diameter as that of the first shield member 19, taking into account the domes 33, i.e. the outside diameter 34.
  • the interrupter is assembled with the aid of a jig 50, which comprises a base 51, three location rods 52 (only two are shown) fixed to the base 51 at equidistant points around its circumference and three location discs 53.
  • the lower two discs 53 are maintained at a desired spacing relative to each other by way of spacers 54 (only one is shown).
  • Assembly is commenced by the insertion of the end-stub 15 of the interrupter into the base 51.
  • the fixed end-ring 23 i.e. the end-ring associated with the fixed contact 11
  • the fixed conductor arrangement consisting of the contact 11 and the stem 13 is mounted on the end-ring 23.
  • the fixed-end ceramic 8 is positioned on top of the end-ring 23, being guided by the lowest of the three location discs 53, and the first shield member 19 is positioned on top of the ceramic 8 so that the lip 36 rests on the upper brazable surface of the ceramic 8.
  • the domes 33 on the shield member 19 are dimensioned so that there is a clearance fit between that member and the ceramic element 8 when the member 19 is positioned in the jigged assembly.
  • the moving conductor arrangement consisting of the contact 12 and the stem 14 is placed on top of the contact 11, followed by positioning of the second shield member 20 on top of the first shield member 19.
  • the upper ceramic element 9 is then placed on top of the lip 36 of the first shield member, being located by the middle locating ring 53. Again, there is a clearance fit between the second shield member and the upper ceramic element 9.
  • a bellows unit (not shown) is then fitted, then the end-stub 16.
  • the bellows unit is held in position by the upper locating ring 53.
  • the end-ring 24 is mounted on the upper ceramic 9.
  • brazing ring is supplied in series with the components concerned.
  • a large weight 55 is placed on top of the end-ring 24 to squeeze the outer joints (e.g. the joint between the ceramic elements 8 and 9 and the lip 36 of the first shield member 19).
  • the whole jigged assembly is then placed into an oven, which is evacuated down to 10 -6 mbar and then heated to a temperature of up to 800° C.
  • both the shield members 19, 20 and the insulator elements 8, 9 expand, but at different rates, the shield members, being copper, expanding at a greater rate than the ceramic elements 8, 9.
  • the brazing agent melts, the shield members start to "float" with respect to the ceramic insulators and, as the temperature increases, the domes 33 of the first shield member and the lip 40 of the second shield member touch the inner walls of their respective ceramic elements to provide an interference fit between these parts, the shield members being then centralised within the assembly.
  • a further increase in temperature causes both the domes 33 and the lip 40 to strain against the ceramic walls; however, because the shield is made from soft copper, the domes and the end-portion of the second shield member adjacent the lip both distort, so that no damage is caused to the ceramic.
  • Figure 6 shows the distortion process of the first and second shield members, whereby the domes 33 are flattened against the ceramic 8, while the end-portion 41 of the second shield member 20 near the lip 40 distorts as shown.
  • the assembly is then allowed to cool to a temperature at which the brazing agent sets and the assembly is made rigid. Upon further cooling, the metal parts of the assembly contract toward their normal dimensions, except those parts which are secured by brazing, e.g. the lip 36 of the first shield member 19 and the lip 40 of the second shield member 20.
  • domes on the first shield member have been described as being essentially hemispherical in shape, in practice any convenient shape may be employed which allows easy deformation on contact with the ceramic housing.

Landscapes

  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
EP19960308893 1995-12-21 1996-12-06 Elektrisch leitender Schirm für einen Vakuumschalter Revoked EP0780868B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9526232A GB2308498B (en) 1995-12-21 1995-12-21 Electrically conductive shield for a vacuum switching device
GB9526232 1995-12-21

Publications (3)

Publication Number Publication Date
EP0780868A2 true EP0780868A2 (de) 1997-06-25
EP0780868A3 EP0780868A3 (de) 1999-04-28
EP0780868B1 EP0780868B1 (de) 2004-02-25

Family

ID=10785861

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19960308893 Revoked EP0780868B1 (de) 1995-12-21 1996-12-06 Elektrisch leitender Schirm für einen Vakuumschalter

Country Status (3)

Country Link
EP (1) EP0780868B1 (de)
DE (1) DE69631641T2 (de)
GB (1) GB2308498B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19946570B4 (de) * 1999-09-29 2007-07-05 Abb Patent Gmbh Vacuumkammer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8039771B2 (en) 2008-08-11 2011-10-18 Eaton Corporation Vacuum envelope including self-aligning end shield, vacuum interrupter, vacuum circuit interrupter and method including the same

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4002867A (en) * 1972-11-01 1977-01-11 Westinghouse Electric Corporation Vacuum-type circuit interrupters with condensing shield at a fixed potential relative to the contacts
NL178680C (nl) * 1979-03-05 1986-05-01 Hazemeijer Bv Werkwijze voor het tot stand brengen van een stompe hardsoldeerverbinding tussen metaal en keramisch materiaal.
DE3173186D1 (en) * 1980-06-30 1986-01-23 Meidensha Electric Mfg Co Ltd A vacuum interrupter and methods of manufacturing the same
DE3202429A1 (de) * 1982-01-26 1983-07-28 Klaus 4232 Xanten Dietzel Schraubverbindung fuer rohrarmaturen und verfahren ihrer herstellung
US4500383A (en) * 1982-02-18 1985-02-19 Kabushiki Kaisha Meidensha Process for bonding copper or copper-chromium alloy to ceramics, and bonded articles of ceramics and copper or copper-chromium alloy
US4665287A (en) * 1985-11-08 1987-05-12 General Electric Company Shield assembly of a vacuum interrupter
DE3806921A1 (de) * 1988-03-03 1989-09-14 Calor Emag Elektrizitaets Ag Vakuumschalterkammer
DE3926619C2 (de) * 1989-07-15 1993-11-04 Calor Emag Elektrizitaets Ag Verfahren zur herstellung einer vakuumschaltkammer
DE3931774A1 (de) * 1989-09-23 1991-04-04 Calor Emag Elektrizitaets Ag Verfahren zur herstellung einer vakuumschaltkammer
US5137202A (en) * 1991-07-15 1992-08-11 Purdy Iii Robert J Pipe joint lead stop and method
US5377900A (en) * 1993-12-29 1995-01-03 At&T Corp. Method of precisely positioning and mating two workpieces

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19946570B4 (de) * 1999-09-29 2007-07-05 Abb Patent Gmbh Vacuumkammer

Also Published As

Publication number Publication date
DE69631641T2 (de) 2004-12-16
GB2308498A (en) 1997-06-25
EP0780868A3 (de) 1999-04-28
GB9526232D0 (en) 1996-02-21
GB2308498B (en) 2000-04-19
DE69631641D1 (de) 2004-04-01
EP0780868B1 (de) 2004-02-25

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