US3469049A - High voltage vacuum device with improved means for inhibiting sparkover adjacent the edge of a tubular metal part - Google Patents

High voltage vacuum device with improved means for inhibiting sparkover adjacent the edge of a tubular metal part Download PDF

Info

Publication number
US3469049A
US3469049A US552231A US3469049DA US3469049A US 3469049 A US3469049 A US 3469049A US 552231 A US552231 A US 552231A US 3469049D A US3469049D A US 3469049DA US 3469049 A US3469049 A US 3469049A
Authority
US
United States
Prior art keywords
edge
bead
adjacent
vacuum device
high 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.)
Expired - Lifetime
Application number
US552231A
Other languages
English (en)
Inventor
Donald W Crouch
Donald R Kurtz
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.)
General Electric Co
Original Assignee
General Electric Co
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
Application filed by General Electric Co filed Critical General Electric Co
Application granted granted Critical
Publication of US3469049A publication Critical patent/US3469049A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • H01H2033/66284—Details relating to the electrical field properties of screens in vacuum switches
    • 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
    • H01H2033/66292—Details relating to the use of multiple screens in vacuum switches
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49087—Resistor making with envelope or housing

Definitions

  • a high voltage vacuum device comprising a tubular metal part having an. annular end portion located in a region of high dielectric stress.
  • the end portion comprises a thin-walled annulus and an annular bead of arcmelted metal substantially aligned therewith, the bead being formed by locally melting the edge of the annulus with an electric arc to produce large grains and a smooth, rounded external surface.
  • This invention relates to a vacuum device for use in high voltage electrical applications and, more particularly, relates to means and a method for improving the ability of the device to withstand high dielectric stresses without sparking over.
  • the edge of a tubular metal part is located in a region of high dielectric stress. It has been recognized that the dielectric stress adjacent this edge can be reduced by deforming this edge region into the general shape of a tore with a relatively large radius of curvature. But this deforming process is a relatively expensive one. Moreover, it requires a significant amount of otherwise unused metal, and the resulting tore consumes space that might be needed for other'purposes in the vacuum device.
  • An object of the present invention is to increase the dielectric strength of a vacuum device in the region adjacent the edge of such a tubular part by inexpensive means which requires little .or no excess metal and con sumes no significant amount of otherwise usable space.
  • Another object is to provide a new and improved method of treating the edge of such a tubular part to increase the vacuum devices capability of withstanding high voltages in the region adjacent said edge.
  • FIG. 1 is a cross-sectional view through a vacuum type electric circuit interrupter embodying one form of the invention.
  • FIG. 3 is an enlarged cross-sectional view of a portion of FIG. 1..
  • FIG. 1 there is shown a vacuumtype circuit interrupter that is designed for high voltage circuit applications.
  • This vacuum-type circuit interrupter comprises a sealed envelope 10 that has its interior evacuated to a pressure of 10 mm. of mercury or lower.
  • the envelope 10 comprises a tubular casing 11 of insulating material and a pair of metal end caps 12 and 13 sealing off the ends of the casing. The end caps are joined to the casing by suitable vacuum-tight glass-to-metal seals 14.
  • the lower contact 18 is a movable contact suitably joined to a movable operating rod 18a.
  • the operating rod 18a extends freely through an opening 19 in the lower end cap, and a flexible metal bellows 20. is provided thereabout to permit movement of the rod 1821 without impairing the vacuum inside the envelope.
  • The" bellows 18 is joined at its respective opposite ends to the end cap 13 and the rod 18a by means of suitable vacuum-tight joints.
  • the interrupter can be closed by driving the lower contact 18 upwardly into a dotted line position 21 where it engages the upper contact 17.
  • the interrupter is thus closed, current can flow through it via parts 17a, 17 18 and 18a.
  • Contact-opening is elfected by returning the lower contact from its dotted line position of engagement to 'the illustrated solid line position.
  • a tubular metal shield 30 For intercepting this metal vapor, a tubular metal shield 30 is provided.
  • This tubular metal shield 30 surrounds the contacts and is mounted on the casing 11 by suitable mounting means 32.
  • a pair of tubular end shields 34 and 35 are also provided; and these end shields are respectively connected to the end caps 12 and 13. These end shields are shown surrounding the respective oposite ends of the central shield 30.
  • the regions immediately adjacent the exposed edges 40, 41, 42 and 43 of the shields are regions of high dielectric stress. In these regions, the lines of force of the electrical field crowd closely together and produce conditions conducive to a sparkover.
  • the present invention is concerned with increasing the amount of voltage that the interrupter can withstand without a sparkover in the high stress regions.
  • FIG. 2 shows such an are 49 established at the annular edge 41 of the central shield 30.
  • One terminal of the are 49 is attached to the edge of the shield and the other to a refractory electrode 50, which is capable of withstanding the high temperature of the are without melting.
  • the electrode 50 is moved rapidly along a circular path 52 that is in substantial alignment with the annular edge 41.
  • the rate at which the electrode 50 is moved is made high enough to avoid any burning of the edge 41 3 but is kept low enough to melt the portion of the edge engaged by the arc. As soon as the arc moves out of a given region, the molten metal solidifies and forms a bead along the edge.
  • FIG. 3 is an enlarged cross-sectional view which shows the head at 55.
  • this bead 55 of arc-melted metal has a rounded, highly-smooth external surface.
  • the bead is in substantial alignment with the thin-walled section of the shield immediately thereadjacent.
  • the external surface of the bead smoothly merges with the cylindrical internal and external surfaces of the adjacent portion of the shield.
  • a factor that is believed to contribute to the roundness and smoothness of the bead surface is the thinness of the immediately adjacent shied wall. Because of this thinness, the arc can melt the edge of the shield wall across its entire thicknes at a given circumferential logation. The resulting pool of molten metal, aparently because of surface tension, tends to develop a peripheral configuration that is generally semicircular, when viewed in cross-section. This shape persists until solidification, after which it is, of course, permanently preserved, In a practical embodiment of the invention, a shield 30 made of nickel and having a wall thickness of about .05 inch is used.
  • the above-described bead-forming process is performed in an inert atmosphere, preferably an argon atmosphere.
  • This inert atmosphere can be maintained about the localized portionof the edge 41 exposed to the are at any given time, but preferably it is maintained around the entire annular edge.
  • the entire beading operation is performed in a chamber filled with argon.
  • the inert atmosphere should be maintained long enough to allow the molten metal of the head to solidify before exposure to air or oxygen.
  • the inert atmosphere serves to inhibit the formation of oxides and the possible burying of oxides in the metal of the bead
  • the shields are suitably assembled in the vacuum interrupter, after which the interupter is subjected to a conventional high temperature bakeout to remove contaminants from its surfaces.
  • Such bakeout removes easily-decomposable oxides that may have formed on the bead surface after its formation. But such bakeouts cannot effectively remove oxides buried just beneath the surface of the metal, and it is therefore important that such oxide formation be minimized, as above-described, during the bead-forming process. It is highly desirable to avoid contaminants, such as oxides, at or near the surface of highly stressed parts in a vacuum, since these contaminants can cause dielectric breakdown at unduly low voltages.
  • the exceptional smoothness of the arc-melted head is believed to be a factor that contributes to the high dielectric strength.
  • Another significant contributing factor is believed to be the larger grain sizes present in the bead, as was pointed out hereinabove. Grain boundaries may be regions of dielectric weakness, and the number of such. boundaries is drastically reduced because of the much larger grain sizes present in our arcmelted bead than elsewhere in the shield.
  • a high voltage vacuum device comprising:
  • said head having a smooth, rounded external surface that is located in a region of high dielectric stress during periods when said vacuum device is energized
  • said bead being so formed as to improve the ability of said high voltage vacuum device to withstand voltages applied between the edge of said thin-walled annulus and an adjacent part at a different potential spaced therefrom by evacuated space within said envelope.

Landscapes

  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
US552231A 1966-05-23 1966-05-23 High voltage vacuum device with improved means for inhibiting sparkover adjacent the edge of a tubular metal part Expired - Lifetime US3469049A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US55223166A 1966-05-23 1966-05-23

Publications (1)

Publication Number Publication Date
US3469049A true US3469049A (en) 1969-09-23

Family

ID=24204445

Family Applications (1)

Application Number Title Priority Date Filing Date
US552231A Expired - Lifetime US3469049A (en) 1966-05-23 1966-05-23 High voltage vacuum device with improved means for inhibiting sparkover adjacent the edge of a tubular metal part

Country Status (3)

Country Link
US (1) US3469049A (ja)
JP (1) JPS459975B1 (ja)
GB (1) GB1110888A (ja)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3917470A (en) * 1970-09-28 1975-11-04 Pavel Xmris Electrostatic precipitator
US4158911A (en) * 1978-04-13 1979-06-26 General Electric Company Method of manufacturing a vacuum-type circuit interrupter
US5594224A (en) * 1993-12-24 1997-01-14 Hitachi, Ltd. Vacuum circuit interrupter

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1273015A (en) * 1913-08-29 1918-07-16 Percy H Thomas Electric insulator.
US2050416A (en) * 1933-07-29 1936-08-11 Harry G Blanchard Rounding an end of a metal part
US2892912A (en) * 1956-12-24 1959-06-30 Gen Electric Vacuum type circuit interrupter
US3209195A (en) * 1961-03-13 1965-09-28 Rca Corp High voltage electron discharge diode
US3307246A (en) * 1963-12-23 1967-03-07 Ibm Method for providing multiple contact terminations on an insulator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1273015A (en) * 1913-08-29 1918-07-16 Percy H Thomas Electric insulator.
US2050416A (en) * 1933-07-29 1936-08-11 Harry G Blanchard Rounding an end of a metal part
US2892912A (en) * 1956-12-24 1959-06-30 Gen Electric Vacuum type circuit interrupter
US3209195A (en) * 1961-03-13 1965-09-28 Rca Corp High voltage electron discharge diode
US3307246A (en) * 1963-12-23 1967-03-07 Ibm Method for providing multiple contact terminations on an insulator

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3917470A (en) * 1970-09-28 1975-11-04 Pavel Xmris Electrostatic precipitator
US4158911A (en) * 1978-04-13 1979-06-26 General Electric Company Method of manufacturing a vacuum-type circuit interrupter
US5594224A (en) * 1993-12-24 1997-01-14 Hitachi, Ltd. Vacuum circuit interrupter

Also Published As

Publication number Publication date
DE1640226B2 (ja) 1975-08-21
GB1110888A (en) 1968-04-24
JPS459975B1 (ja) 1970-04-10
DE1640226A1 (de) 1970-05-27

Similar Documents

Publication Publication Date Title
US3210505A (en) Electrode structure for an electric circuit interrupter
US3622724A (en) Vacuum-type circuit interrupter having contacts with improved arc-revolving means
US3980850A (en) Vacuum interrupter with cup-shaped contact having an inner arc controlling electrode
US3089936A (en) Contact structure for an electric circuit interrupter
US3462572A (en) Vacuum type circuit interrupter having contacts provided with improved arcpropelling means
JPH0652761A (ja) 開閉器
US3889080A (en) Vacuum interrupter shield protector
CN108352272B (zh) 通过将接触间隙远离中心凸缘轴向位置移动来最大化cu-cr浮动中心罩组件的壁厚
US2892912A (en) Vacuum type circuit interrupter
EP0138478B1 (en) Vacuum-type circuit interrupters
US3489873A (en) Triggered vacuum type circuit interrupter
US3185797A (en) Vacuum-type circuit interrupter with improved arc splitting means
JPH07123016B2 (ja) 回路遮断器用真空ボトル
US3792214A (en) Vacuum interrupter for high voltage application
EP0468294B1 (en) Puffer type gas-insulated circuit breaker
EP0088442A2 (en) Puffer type gas-blast circuit breaker
US3469049A (en) High voltage vacuum device with improved means for inhibiting sparkover adjacent the edge of a tubular metal part
US4020304A (en) Two-material vapor shield for vacuum-type circuit interrupter
US4088860A (en) Vacuum interrupter for high voltage application
US3845262A (en) Contact structures for vacuum-type circuit interrupters having cantilevered-supported annularly-shaped outer arc-running contact surfaces
US3546407A (en) Vacuum-type circuit interrupter
US2972032A (en) Vacuum interrupter
US4478347A (en) Unitary end closure and seal shield member for vacuum interrupter
CA1068754A (en) Compact high-current vacuum circuit interrupter comprising a metal housing that is electrically connected to one contact of the interrupter
US4574169A (en) Bimetallic arc shield