Electrical contact for high voltage power circuit current

{
  "publication_number": "US3801764A",
  "country": "US",
  "kind": "A",
  "title": "Electrical contact for high voltage power circuit current",
  "abstract": "In a high voltage, gas-filled power circuit current interruption apparatus, an improved electrical contact comprising a conductive base member, a conductive mounting member disposed in and electrically coupled to the base member, and a conductive electrode, disposed in the mounting member. The mounting member supports the electrode on the contact and is constructed of an electrically conductive composition which has a coefficient of thermal expansion similar to that of the electrode. Thermal stress resulting from heating of the electrode and mounting member by current arcs remains approximately constant over a specified temperature range, and damage caused thereby is prevented.",
  "claims": [
    "1. In a high voltage power circuit current interruption apparatus, of the type filled with a gaseous dielectric medium and including at least one movable electrically conductive bridge coupling the electrical contacts conducting current through the apparatus, an improved electrical contact, comprising a base member having an opening in at least one end thereof; a mounting member, including an opening in at least one end thereof, disposed in one end of said base member; and an electrode, slidably disposed in and frictionally engaging the other end of said mounting member.",
    "2. The electrical contact as recited in claim 1, wherein said electrode, mounting member and base member are hollow and have openings in the ends thereof and vent from the apparatus gases generated by current arcIng during interruption of the current conducted between the contacts by the conductive bridge.",
    "3. The electrical contact as recited in claim 2, wherein said electrode, mounting member and base member are annular in shape, and wherein said electrode includes a tapered longitudinal bore which forms a nozzle therein.",
    "4. The electrical contact as recited in claim 1, wherein said mounting member and said electrode are constructed of conductive compositions each having similar coefficients of thermal expansion, whereby thermal stress applied to said electrode by said mounting member in response to heating by current arcing remains approximately constant over a specified temperature range.",
    "5. The electrical contact as recited in claim 4, wherein said mounting member is constructed of an electrically conductive metallic composition consisting of about 36 percent nickel and about 64 percent iron, and wherein said electrode is constructed of graphite.",
    "6. The electrical contact as recited in claim 4, wherein said mounting member is constructed of an electrically conductive metallic composition consisting of about 28 percent nickel, about 18 percent cobalt and about 54 percent iron, and wherein said electrode is constructed of graphite.",
    "7. The electrical contact as recited in claim 4, wherein said electrode includes upper and lower portions of different diameters, the outside diameter of the upper portion of said electrode being about 0.1 to about 0.5 percent greater than the inside diameter of said mounting member and the outside diameter of the lower portion of said electrode at room temperature, said lower portion of said electrode being disposed in said mounting member for mounting said electrode therein.",
    "8. The electrical contact as recited in claim 1, wherein said mounting member comprises a thin elastic annular wall of metallic material, expansion of said electrode against said mounting member in response to heating by current arcing being elastically absorbed by said mounting member wall.",
    "9. The electrical contact as recited in claim 8, wherein said mounting member is constructed of an electrically conductive metallic composition consisting of steel type ST 35, and wherein said electrode is constructed of graphite."
  ],
  "cpc": [
    "H01H 33/7069",
    "H01H 33/7061"
  ],
  "assignees": [
    "SIEMENS AG"
  ],
  "filing_date": "1973-03-22",
  "publication_date": "1974-04-02",
  "grant_date": "1974-04-02",
  "priority_date": "1972-03-28",
  "application_number": "US-3801764D-A",
  "family_id": "5840783",
  "citations": [
    "DE1269230B",
    "DE1965853A1",
    "FR1491851A"
  ]
}