US3624325A - Vacuum-type circuit interrupter with weld-resistant contact material consisting essentially of copper and beryllium - Google Patents

Vacuum-type circuit interrupter with weld-resistant contact material consisting essentially of copper and beryllium Download PDF

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Publication number
US3624325A
US3624325A US888398A US3624325DA US3624325A US 3624325 A US3624325 A US 3624325A US 888398 A US888398 A US 888398A US 3624325D A US3624325D A US 3624325DA US 3624325 A US3624325 A US 3624325A
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beryllium
contacts
copper
vacuum
alloy
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US888398A
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English (en)
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Fordyce H Horn
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General Electric Co
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General Electric Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/02—Contacts characterised by the material thereof
    • H01H1/0203—Contacts characterised by the material thereof specially adapted for vacuum switches

Definitions

  • n ABSTRACT Discloses a vacuum-type circuit interrupter having a pair of contacts relatively movable into and out of engagement with each other.
  • the contacts have their circuitmaking and breaking regions formed of an allo sentially of copper and beryllium, the berylliu in a quantity of about 6 to 19 percent b y consisting esm being present WELD-RESISTANT CONTACT MATERIAL CONSISTING ESSENTIALLY OF COPPER AND y weight of the alloy.
  • BERYLLIUM ditional metallic constituents that are substantially insoluble in the solid state in copper and beryllium and have effective freezin than 860 C.
  • the alloy is substantially free of ad 6 Claims, 2 Drawing Figs.
  • This invention relates to a vacuum-type circuit interrupter and, more particularly, to contact structure for such an inter rupter.
  • the aforesaid application discloses and claims vacuum-gap electric discharge devices having arc electrodes made of a copper-beryllium alloy containing 0.1 to l 1.5 percent beryllium by weight.
  • the purpose of the beryllium in such alloy is to serve as a getter that reacts with any oxygen present in the alloy, both during processing and during operation of the discharge device, to maintain the device essentially free of evolved oxygen during the crucial stages of its operation.
  • the present application is also concerned with a discharge device that has arc-electrodes containing beryllium. But in the electrodes of the present application, the beryllium acts not only as a getter but as an antiweld agent, as will soon be described.
  • the vacuum discharge device is a vacuum interrupter with electrodes, or contacts, movable into and out of engagement with each other, animportant requirement that must be met is that the contacts must not weld together with objectionable welds, even under the most severe operating conditions. In meeting this requirement, it is important to prevent the formation not only to those welds that are so strong that they cannot be broken except with excessive force during a subsequent opening operation but also those welds that cannot be fractured cleanly and without production of a jagged interface between the two contacts. The production of such a jagged interface leads to excessive contact wear and also to reduced dielectric strength.
  • One way of meeting the aforesaid antiweld requirement is to form the contacts of one of the alloys disclosed and claimed in US. Pat. No. 3,246,979-Lafferty et al., assigned to the assignee of the present invention.
  • Each of these alloys consists essentially of a major constituent which is a good-conductivity, nonrefractory metal and a minor constituent which is a metal having a lower freezing temperature than the major con stituent and little or no solid-state solubility in the major constituent, the minor constituent being present in a quantity of a few per cent or less by weight of the alloy.
  • Such alloys are copper-bismuth, copper-lead, silver-bismuth, and silver-lead, each alloy containing a few per cent or less by weight of the second-mentioned or minor constituent.
  • the main purpose of the minor constituent is to act as a weld-inhibiting agent that weakens any weld formed between the contacts.
  • an object of this invention is to provide a vacuum interrupter that has contacts capable of meeting the above-described antiweld requirement and yet are free of the low-freezing point, relatively volatile, insoluble minor constituents of the aforesaid Lafferty et al. patent.
  • Another object is to provide the vacuum interrupter with contacts that contain beryllium to act as an effective getter of oxygen, as described in my aforesaid application, and that are also capable of meeting the object set forth in the immediately preceding paragraph.
  • the vacuum interrupter is provided with contacts relatively movable into and out of engagement and having their circuit-making and cricuit breaking regions made of an alloy consisting essentially of copper and beryllium, the beryllium being present in a quantity of between about 6 and 19 per cent by weight of the alloy.
  • the alloy is substantially free of additional metallic constituents that are insoluble in the solid state in copper or beryllium and have effective freezing points lower than that of the copper-beryllium eutectic (i.e., 860 C).
  • FIG. 1 is a sectional view of a vacuum-type circuit interrupter embodying one form of the invention.
  • FIG. 2 is an enlarged perspective view of one of the contacts of the interrupter of FIG. 1.
  • a highly evacuated envelope 10 comprising a casing 11 of a suitable insulating material, such as glass, and a pair of metallic end caps 12 and 13, closing off the ends of the casing.
  • Suitable seals 14 are provided between the end caps and the casing to render the envelope l0 vacuum-tight.
  • the normal pressure within the envelope 10 under static conditions is lower than 10 mm. of mercury so that a reasonable assurance is bad that the mean free path for electrons will be longer than the potential breakdown paths in the envelope.
  • casing 11 The internal insulating surfaces of casing 11 are protected from the condensation of arc-generated metal vapors thereon by means of a tubular metallic shield 15 suitably supported on the casing 11 and preferably isolated from both end caps 12 and 13. This shield acts in a well-known manner to intercept arcgenerated metallic vapors before they can reach the casing 11.
  • the upper contact 17 is a stationary contact suitably attached to a conductive rod 170, which at its upper end is united to the upper end cap 12.
  • the lower contact 18 is a movable contact joined to a conductive operating rod 180 which is suitably mounted for vertical movement. Downward motion of the contact 18 separates the contacts and opens the interrupter, whereas return movement of contact 18 reengages the contacts and thus closes the interrupter.
  • a typical gap length when the contacts are fully open is about one-half inch.
  • the operating rod 18a projects through an opening in the lower end cap 13, and a flexible metallic bellows 20 provides a seal about the rod 18a to allow for vertical movement of the rod without impairing the vacuum inside the envelope 10.
  • the bellows 20 is secured in sealed relationship at its respective opposite ends to the operating rod 180 and the lower end cap 13.
  • All of the internal parts of the interrupter are substantially free of surface contaminants. These clean surfaces are obtained by suitably processing the interrupter, as by baking it out during its evacuation. A typical bakeout temperature is 400 C.
  • the contacts 17 and 18 are effectively freed of gases absorbed internally of the contact body so as to preclude evolution of these gases during high current arcing. The manner in which these internal gases are removed will be referred to in more detail hereinafter.
  • each contact is of a disk shape and has one of its major surfaces facing the other contact.
  • the central region of each contact is formed with a recess 29 in this major surface and an annular circuit-making and circuit breaking area 30 surrounds this recess.
  • These annular circuit-making and breaking areas 30 abut against each other when the contacts are in their closed position of FIG. 1, and are of such a diameter that the current flowing through the closed contacts follows a loopshaped path L, as is indicated by the dotted lines of FIG. 1.
  • Current flowing through this loop-shaped path has a magnetic effect which acts in a known manner to lengthen the loop.
  • the magnetic effect of the current flowing through the path L will impel the arc radially outward.
  • This circumferentially acting magnetic force is preferably produced by a series of slots 32 provided in the disks and extending from the outer periphery of the disks radially inward by generally spiral paths, as is shown in FIG. 2.
  • slots 32 correspond to similarly designated slots in the aforementioned Schneider patent and thus, force the current flowing to or from an arc terminal located at substantially any angular point on the outer peripheral region of the disk to follow a path that has a net component extending generally tangentially with respect to the periphery in the vicinity of the arc.
  • This tangential configuration of the current path results in the development of a net tangential force component, which tends to drive the arc in a circumferential direction about the contacts.
  • the arc may divide into a series of parallel arcs, and these parallel arcs move rapidly about the contact surface in a manner similar to that described hereinabove.
  • an object of this invention is to provide contacts capable of meeting severe antiweld requirements and yet free of the lowfreezing point, relatively volatile, insoluble secondary constituents of the aforesaid Lafferty et al. patent. l find that these requirements can be met by forming the circuit-making and circuit breaking portions 30 of the vacuum interrupter contacts of an alloy consisting essentially of copper and beryllium, the beryllium being present in a quantity of between about 6 and 19 percent by weight of the alloy.
  • the alloy is free of additional metallic constituents that are insoluble in the solid state in copper and beryllium, and have freezing points lower than that of the copper-beryllium eutectic, which is 860 C.
  • a specific alloy which has shown exceptional ability to meet these requirements is a copper-beryllium alloy consisting essentially of copper and beryllium, the beryllium being present in a quantity of 7 percent by weight of the alloy.
  • intermetallic compound phase Be Cu When the quantity of beryllium is increased beyond about l 1.5 weight percent, some of the intermetallic compound phase Be Cu is formed.
  • the intermetallic compound is very brittle material, and its presence increases the brittleness of the overall contact material. It appears, however, that about 19 percent beryllium can be added to copper before excessive brittleness occurs.
  • the intermetallic phase when beryllium is present in amounts between I 1.5 and 19 percent, there appears to be a sufficient amount of the B phase remaining to adequately offset the brittleness of the intermetallic compound phase. Amounts of beryllium greater than about 19 percent impart so much brittleness that is becomes impractical to machine the material into contacts or to subject them to closing impacts without risking cracking.
  • additional constituents that are substantially insoluble in copper and beryllium in the solid state
  • additional constituents that have a solid-state solubility in copper and beryllium of less than about two per cent by weight of the alloy considered at the freezing temperature of said additional constituent.
  • Bismuth and other weld-inhibiting metals mentioned in the aforesaid Lafferty et al. patent are examples of such additional constituents.
  • each separate constituent first should be suitably processed to free it of sorbed gases and other contaminants, as, for example, by the zonerefining process described in US. Pat. No. 3,234,35l-l-lebb, assigned to the assignee of the present invention.
  • the constituents are then melted and appropriately mixed together while they are in the liquid state, after which the temperature is lowered to cause the constituents to solidify and form the solid alloy.
  • a vacuum-type electric circuit interrupter comprising:
  • said contacts having circuit-making and breaking regions formed of an alloy consisting essentially of copper and beryllium,
  • the beryllium being present in a quantity of between about 6 and 19 percent by weight of the copper-beryllium alloy
  • said alloy being substantially free of additional metallic constituents that are substantially insoluble in the solid state in copper and beryllium and have effective freezing points lower then 860 C.

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  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
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US888398A 1969-12-29 1969-12-29 Vacuum-type circuit interrupter with weld-resistant contact material consisting essentially of copper and beryllium Expired - Lifetime US3624325A (en)

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US88839869A 1969-12-29 1969-12-29

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US (1) US3624325A (enrdf_load_stackoverflow)
JP (1) JPS548858B1 (enrdf_load_stackoverflow)
DE (1) DE2063537C2 (enrdf_load_stackoverflow)
FR (1) FR2074422A6 (enrdf_load_stackoverflow)
GB (1) GB1288339A (enrdf_load_stackoverflow)
SE (1) SE381771B (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3968640A (en) * 1974-09-16 1976-07-13 Hughes Aircraft Company Digital watch with elastomer housing block and flexible printed circuitry
US4028514A (en) * 1974-12-03 1977-06-07 General Electric Company High current vacuum circuit interrupter with beryllium contact

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3497755A (en) * 1966-07-01 1970-02-24 Gen Electric Vacuum devices with electrode members containing oxygen - reactive minor constitutent

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1251406B (enrdf_load_stackoverflow) * 1962-01-24
FR1385794A (fr) * 1963-01-30 1965-01-15 Thomson Houston Comp Francaise Perfectionnements apportés à un interrupteur de circuit électrique du type interrupteur à vide

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3497755A (en) * 1966-07-01 1970-02-24 Gen Electric Vacuum devices with electrode members containing oxygen - reactive minor constitutent

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3968640A (en) * 1974-09-16 1976-07-13 Hughes Aircraft Company Digital watch with elastomer housing block and flexible printed circuitry
US4028514A (en) * 1974-12-03 1977-06-07 General Electric Company High current vacuum circuit interrupter with beryllium contact

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Publication number Publication date
SE381771B (sv) 1975-12-15
GB1288339A (enrdf_load_stackoverflow) 1972-09-06
JPS548858B1 (enrdf_load_stackoverflow) 1979-04-19
FR2074422A6 (enrdf_load_stackoverflow) 1971-10-01
DE2063537C2 (de) 1982-12-30
DE2063537A1 (de) 1971-07-15

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