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US3270172A - Switch having an arc stabilizing electrode - Google Patents

Switch having an arc stabilizing electrode Download PDF

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Publication number
US3270172A
US3270172A US449246A US44924665A US3270172A US 3270172 A US3270172 A US 3270172A US 449246 A US449246 A US 449246A US 44924665 A US44924665 A US 44924665A US 3270172 A US3270172 A US 3270172A
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US
United States
Prior art keywords
switch
electrode
electrodes
arcing
contact
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
US449246A
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English (en)
Inventor
John N Chubb
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.)
English Electric Co Ltd
Original Assignee
English Electric Co 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
Application filed by English Electric Co Ltd filed Critical English Electric Co Ltd
Application granted granted Critical
Publication of US3270172A publication Critical patent/US3270172A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01H33/664—Contacts; Arc-extinguishing means, e.g. arcing rings
    • 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
    • H01H33/664—Contacts; Arc-extinguishing means, e.g. arcing rings
    • H01H33/6646—Contacts; Arc-extinguishing means, e.g. arcing rings having non flat disc-like contact surface

Definitions

  • This invention relates to vacuum electric switches having electrodes between which arcing can take place.
  • the invention is particularly concerned with switches in which these switch electrodes can be moved into and out of contact with one another and therefore they will be referred to hereinafter, where appropriate, as switch contacts.
  • a vacuum electric switch Before a vacuum electric switch can be put into normal operation it is necessary for it first to be current conditioned.
  • the process of current conditioning is carried out in order to remove contaminating layers from the regions of the switch electrode surfaces which are accessible for arcing. If this were not done, the gas evolved from the contaminating layers by arcing during normal operation would cause the vacuum to decay and give rise to malfunction of the switch.
  • the current conditioning is performed during the vacuum processing of the switch structure after the gas pressure in the envelope has been reduced, possibly with the aid of baking, to between 10- millimetres of mercury.
  • the conditioning process consists of repeatedly drawing the are between the main switch electrodes, starting at a current of about 50 amps and increasing progressively to a few hundred amps as the pressure pulses associated with each arcing period diminish with the removal of the contaminating layers from the switch electrodes.
  • the duration of the initial arcing periods may be 10 milliseconds, and as the contamination is removed the arcing duration may be increased along with the arcing current to achieve the most rapid and effective conditioning of the switch electrodes.
  • the ultimate pressure in the switch after full vacuum processing and conditioning may be between 10- and 10' millimetres of mercury.
  • the current in a vacuum arc discharge may be carried by a multiplicity of individual and separate arc channels, each channel typically carrying between 100 and 200 amperes.
  • the arcing channels which strike initially over the centre portion of the switch electrodes repel one another and consequently tend to move outwardly. At low currents this outward movement may be slight, but as the full capacity current of the switch is approached, the outward movement causes the arc channels to extend out towards the furthermost edges of the electrodes.
  • FIGURES l and 2 are diagrammatic sections throug one embodiment of vacuum switch, details of the casing which form no part of the invention having been omitted. The contacts are shown open in FIGURE 1 and closed in FIGURE 2.
  • FIGURE 3 is a diagrammatic section through a second embodiment of vacuum switch, the contacts being shown open.
  • the switch comprises two butt contacts 10, 11 the contact 10 being stationary and the contact 11 movable towards or away from the contact 10.
  • the contacts have flanged heads 10a, 11a, which are formed with flat circular contact surfaces 10b, 11b. Outwardly of these surfaces the heads are chamfered to form two annular surfaces 100, 110 of truncated conical shape which are directed away from one another.
  • annular space 12 is left between the surfaces 100, 110, which is of wedge shaped cross-section diverging in the radially outward direction.
  • a stabilizing electrode 13 of cylindrical shape Surrounding, but spaced from, the heads of the two contacts is a stabilizing electrode 13 of cylindrical shape having a fiat annular web 13a integral therewith and projecting from the inner wall of the cylinder into the space between the surfaces 100, 11c.
  • the second embodiment of vacuum switch shown in FIGURE 3' comprises an outer ring contact 16 and an inner solid cylindrical contact 17, the outer contact being supported on an actuating rod 18 movable along its length in either direction to cause the outer contact 16 to move into or out of abutment with the inner contact 17.
  • the inner wall of the outer contact 16 has a cylindrical 1 contact surface 16b and frusto-conical surfaces 160 which are inclined or flared outwardly from opposite ends of the surface 16b.
  • the inner contact 17 has a cylindrical contact surface 17b for engagement with the surface 161) and frusto-conical surfaces which are inclined or tapered towards the axis of contact 17 from opposite ends of the surface 17b.
  • two annular spaces 19 are formed between opposed pairs of surfaces 160, 170, the spaces being of wedge-shaped crosssection.
  • Adjacent opposite ends of the contacts 16, 17 are disc shaped stabilizing electrodes 20, 20' located normal to the axis of the contact 17, each having an annular flange 20a integral therewith and coaxial with the axis of the contact 17. Each flange 20a projects from the disc into the adjacent space 19 between the surfaces 16c, 170 of the contacts.
  • the electrode 20' has a central opening through which extends a rod 21 in spaced relation thereto, the rod supporting the contact 17.
  • each channel of the vacuum arc discharge takes a conical from with the apex located at a small luminous spot on the cathode and the current in this cone tends to be maintained in a line of sight geometry so that a discharge between the two electrodes will prefer to avoid any non-line of sight path between the electrode surfaces.
  • the manner in which these two aspects of vacuum arc behaviour may be employed to achieve restriction of the area available for arcing of the two cooperating vacuum switch electrodes may be understood with respect to the diagrams shown in FIGURES 1 and 2.
  • FIGURE 2 shows two cooperating electrodes made of the same material whose outer surfaces have interposed between them an annular web 13a in a stabilizing electrode 13, which is made from the same material as the two electrodes.
  • annular web 13a in a stabilizing electrode 13, which is made from the same material as the two electrodes.
  • arcing is initiated between the two cooperating surfaces b and 11b.
  • the arc channels will tend to move away from these cooperating surfaces towards the outer conical surfaces of the electrodes 10c and 11c.
  • the aperture in the annular web acts on the individual arc channels so as to prevent movement beyond the region specified by this aperture.
  • each of two such are channels would require similar discharge voltage to any of the arc channels between the two main electrode surfaces within the limit of the aperture of the annular web, existence of the series are channels is energetically inadmissible, because the discharge voltage necessary would be twice that for areing within the aperture.
  • the mechanism of stabilization described is also applicable for combinations of electrode material satisfying the basic requirement that the voltages of the line of sight discharge between the two main electrodes shall be less than the voltage across any series connection of discharge paths, including the stabilizer electrode. If, for example, the two main electrodes are made of one type of material and the stabilizer is made of a second, different, material then the above requirement is that the sum of the discharge voltages between the first and second materials and between the second and first materials shall be greater than the discharge voltage between the two electrodes of the first material.
  • the two main electrodes are made of two different materials, the first and second materials, and the stabilizer is made of a third material, then the requirement of stabilization will be satisfied for arcing in one direction if the discharge voltages between first and third, and third and second materials is greater than between the first and second materials, and for arcing in the reverse direction that the discharge voltage between the second and third and between the third and first shall be greater than between the second and first materials.
  • this electrode may take some part in the maintenance of the vacuum environment between the two main switch electrodes.
  • the stabilizing electrode will be subjected to heating from radiation from nearby discharges and also to bombardment by energetic particles from the main arcing electrodes. It may therefore be advantageous for this stabilizing electrode or electrodes, to be made from a getter material such as titanium, zirconium or tantalum so that such heating and bombardment may lead to absorption of any small quantities of gasses liberated from the main electrodes during normal operation of the switch.
  • an electrical connection from the stabilizing electrode to the outside of the vacuum switch can be provided so that arcing between the stabilizing electrode and either contact may be deliberately initiated during the conditioning process.
  • said inner electrode having an outer surface comprising a first surface portion of constant diameter along its length and second and third surface portions extending from opposite ends of said first surface portions and each having, at all positions along its length, a diameter less than that of the first portion,
  • said outer electrode having an inner surface comprising a first surface portion of constant diameter along its length and disposed opposite the first surface portion of the inner electrode, and second and third surface portions, extending from opposite ends of the first surface portion, each having, at all positions along its length, a diameter greater than that of the first portion, said second and third surface portions lying opposite the second and third surface portions respectively of the inner electrode,
  • first cylindrical stabilising electrode lying between, but spaced from, the second surface portions of the inner and outer switch electrodes
  • said stabilising electrodes being made of a material satisfying the condition that the voltages of the line of sight discharge between the portions of constant diameters shall be less than the voltage across any series connection of discharge paths including either stabilising electrode, and means for moving one said switch electrode into and out of contact with the other switch electrode.
  • a vacuum electric switch according to claim 1 wherein the surface portions of the inner and outer electrodes which are exposed to one another have been current conditioned by drawing an arc therebetween.
  • ROBERT K. SCHAEFER Primary Examiner.
  • ROBERT S. MACON Examiner.

Landscapes

  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
US449246A 1961-06-30 1965-04-19 Switch having an arc stabilizing electrode Expired - Lifetime US3270172A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB23647/61A GB978973A (en) 1961-06-30 1961-06-30 Improvements in and relating to vacuum electric switches

Publications (1)

Publication Number Publication Date
US3270172A true US3270172A (en) 1966-08-30

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ID=10199018

Family Applications (1)

Application Number Title Priority Date Filing Date
US449246A Expired - Lifetime US3270172A (en) 1961-06-30 1965-04-19 Switch having an arc stabilizing electrode

Country Status (4)

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US (1) US3270172A (de)
CH (1) CH396143A (de)
DE (1) DE1191461B (de)
GB (1) GB978973A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3575564A (en) * 1969-09-10 1971-04-20 Allis Chalmers Mfg Co Vacuum-type electric circuit interrupter
US3590197A (en) * 1968-10-31 1971-06-29 Allis Chalmers Mfg Co Electrical contacts containing gettering material
US3592987A (en) * 1968-03-19 1971-07-13 Westinghouse Electric Corp Gettering arrangements for vacuum-type circuit interrupters comprising fibers of gettering material embedded in a matrix of material of good conductivity
US4135071A (en) * 1976-03-17 1979-01-16 General Electric Company Vacuum circuit interrupter with disc-shaped beryllium contacts

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1065886A (en) * 1963-10-11 1967-04-19 Ass Elect Ind Improvements relating to vacuum-switch contacts
US4021628A (en) * 1975-01-20 1977-05-03 Westinghouse Electric Corporation Vacuum fault current limiter

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1784302A (en) * 1926-11-15 1930-12-09 California Inst Of Techn Process for conditioning electric switches
GB389463A (en) * 1930-09-07 1933-03-06 Siemens Ag A vacuum electric switch
US2900476A (en) * 1956-04-17 1959-08-18 Era Patents Ltd Electrical switching apparatus
US2976382A (en) * 1959-06-29 1961-03-21 Gen Electric Arc extinguishing structure for an electric circuit interrupter
US3014110A (en) * 1959-10-29 1961-12-19 Gen Electric Alternating current vacuum circuit interrupter
US7996304B1 (en) * 1999-08-27 2011-08-09 Federal Home Loan Mortgage Corporation Risk-based reference pool capital reducing systems and methods

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE596966C (de) * 1930-05-28 1934-05-14 Aeg Vorrichtung fuer Vakuumschalter zum Entgasen der Kontakte
DE643192C (de) * 1933-02-19 1937-03-31 Siemens Schuckertwerke Akt Ges Elektrischer Schalter
DE603883C (de) * 1933-03-23 1934-10-10 Bbc Brown Boveri & Cie Schaltanordnung
BE412834A (de) * 1934-12-18

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1784302A (en) * 1926-11-15 1930-12-09 California Inst Of Techn Process for conditioning electric switches
GB389463A (en) * 1930-09-07 1933-03-06 Siemens Ag A vacuum electric switch
US2900476A (en) * 1956-04-17 1959-08-18 Era Patents Ltd Electrical switching apparatus
US2976382A (en) * 1959-06-29 1961-03-21 Gen Electric Arc extinguishing structure for an electric circuit interrupter
US3014110A (en) * 1959-10-29 1961-12-19 Gen Electric Alternating current vacuum circuit interrupter
US7996304B1 (en) * 1999-08-27 2011-08-09 Federal Home Loan Mortgage Corporation Risk-based reference pool capital reducing systems and methods

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3592987A (en) * 1968-03-19 1971-07-13 Westinghouse Electric Corp Gettering arrangements for vacuum-type circuit interrupters comprising fibers of gettering material embedded in a matrix of material of good conductivity
US3590197A (en) * 1968-10-31 1971-06-29 Allis Chalmers Mfg Co Electrical contacts containing gettering material
US3575564A (en) * 1969-09-10 1971-04-20 Allis Chalmers Mfg Co Vacuum-type electric circuit interrupter
US4135071A (en) * 1976-03-17 1979-01-16 General Electric Company Vacuum circuit interrupter with disc-shaped beryllium contacts

Also Published As

Publication number Publication date
DE1191461B (de) 1965-04-22
GB978973A (en) 1965-01-01
CH396143A (fr) 1965-07-31

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