US3683139A - Contact structures for vacuum-type circuit breakers - Google Patents

Contact structures for vacuum-type circuit breakers Download PDF

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Publication number
US3683139A
US3683139A US874649A US3683139DA US3683139A US 3683139 A US3683139 A US 3683139A US 874649 A US874649 A US 874649A US 3683139D A US3683139D A US 3683139DA US 3683139 A US3683139 A US 3683139A
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United States
Prior art keywords
arc
contact
contacts
vacuum
delta
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Expired - Lifetime
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US874649A
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English (en)
Inventor
Howard C Ludwig
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.)
Westinghouse Electric Corp
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Westinghouse Electric Corp
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Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
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Publication of US3683139A publication Critical patent/US3683139A/en
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    • 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
    • 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
    • H01H33/6644—Contacts; Arc-extinguishing means, e.g. arcing rings having coil-like electrical connections between contact rod and the proper contact
    • H01H33/6645—Contacts; Arc-extinguishing means, e.g. arcing rings having coil-like electrical connections between contact rod and the proper contact in which the coil like electrical connections encircle at least once the contact rod

Definitions

  • the present invention refers to vacuum-type circuit interrupters in which an arc is established'within an evacuated enclosure.
  • One of the contacts may be secured to a metallic bellows and may be the movable contact engaging and disengaging the othercooperable contact, which is generally the stationary contact.
  • the separable contacts make contacting engagement for carrying the line current.
  • suitable means effects separating motion of the movable contact away from the other contact, thereby establishing an arc within the evacuated enclosure.
  • both of the separable contacts of a vacuum-type circuit interrupter are generally conically shaped, and are provided with continuous spirally shaped shoulders, which progressively assume a greater diameter and, additionally, attain a greater distance from the tip of the particular contact.
  • the rotation of the arc about the two separated contacts causes the arc length to assume a considerably greater length, and also by the induced magnetic effects causes the arc terminals to progressively move along the continuous spiral-shaped shoulders and thereby to constantly increase the arc length.
  • a more specific object of the present invention is the provision of a pair of separable contacts, which by their configuration cause the arc to assume a greater and greater length during the rotation of the are about the contact structures.
  • a more specific object of the present invention is the provision of an improved separable contact structure for a vacuum-type circuit interrupter in which each contact is of generally conical shape with continuous spiral-shaped shoulders to provide thereby a spirallyarranged arc-temiinal surface of progressively greater diameter, and additionally having a greater length from the extremity tip of the particular contact.
  • FIG. 1 is a side elevational view, partially in vertical section, of a vacuum-type circuit interrupter embodying one form of the present invention
  • FIG. 2 is a considerably enlarged perspective view of one of the contact structures illustrated in FIG. 1;
  • FIGS. 3 and 4 illustrate respectively side elevational and top plan views of the contact construction shown in FIG. 1;
  • FIGS. 5 and 6 illustrate, respectively, side elevational and top plan views of another contact configuration embodying the principles pf the present invention
  • FIGS. 7 and 8 illustrate still a further contact configuration embodying the principles of the present invention
  • FIG. 9 is a diagrammatic view illustrating the theoretical principles involved in my invention.
  • FIG. 10 is a graph illustrating the induced magnetic forces involved as a function of the particular continuous spiral-shaped shoulder configuration.
  • FIG. 1 there is shown a vacuumtype circuit interrupter comprising an envelope l0 evacuated to a pressure of 10 mm. of mercury or lower.
  • the envelope 10 comprises a tubular casing 11 of insulating material and metallic end caps 12 and 13 joined to the tubular casing 11 at its opposite ends by suitable vacuum-tight seals 14.
  • the upper contact 17 is a stationary contact suitably attached to a conductive rod 17a, which at its upper end is united to the upper end cap 12.
  • the lower contact 18 is a movable contact attached to a conductive operating rod 18a, which is suitably mounted for vertical movement. Upward movement of the contact 18 from its solid line position to its dotted line position engages the contacts, and thus closes the interrupter, whereas return movement in a downward direction separates the contacts, draws an are. 15, and opens the vacuumtype circuit interrupter.
  • the operating rod 18a projects freely through an opening in the lower end cap 13, and a flexible metallic bellows 20 provides a seal about rod 18a to allow for vertical movement of the rod without impairing the vacuum inside envelope 10.
  • the bellows 20 is secured in sealed relationship at its respective opposite ends to the operating rod 18a and to the lower end cap 13.
  • the shielding comprises a tubular main shield 21 surrounding the arcing gap 27 and located between the insulating casing 11 and the arcing gap.
  • This main shield 21 extends longitudinally of casing 11 for substantial distances on opposite sides of the arcing gap 27.
  • the tubular main condensing shield 21 has an enlarged diameter in the region around the contacts 17 and 18, as compared to its diameter near its ends, so as to give added clearance between the shield and the contacts 17, 18.
  • the main shield is suitably supported on the insulating casing 1 l and is maintained at a voltage approximately midway that of the contacts 17 and 18 when the interrupter is opened.
  • auxiliary shields 22, 23 Surrounding the main shield 21 at its respective opposite ends are auxiliary shields 22, 23. These auxiliary shields are electrically connected to the end caps 12 and 13, respectively, and therefore are at the same potential as the contacts 17 and 18, respectively.
  • auxiliary shields 24, 25 are also of a generally tubular form and are electrically connected to end caps 12 and 13, respectively.
  • the upper auxiliary shield 24 is at the same potential as upper contact 17, and the lower shield 25 is at the same potential as lower contact 18.
  • the present invention is particularly concerned with the contact structure l7, 18 for a vacuum-type circuit interrupter 10, such as illustrated in FIG. 1.
  • a study of prior art reveals the importance of contact configuration with respect to the dissipation and distribution of the vacuum are energy as a function of the current flowing in the arc-forming cycle of an alternating current circuit and self-magnetic field forces, which develop as a consequence. It is also common knowledge that a loop form of current conducting lines v occurring when the cathode spots move radially outwardly from the axis develops magnetic field forces, which tend to lengthen the current-conducting loop initiated.
  • my invention provides a submissive track or path for cathode spots, which causes a lengthening path for current conduction and inhibits the pinch effect from developing to concentrate the current flow through the contact surface.
  • cathode spots From an examination of surfaces over which cathode spots haveoperated it is observed that they tend to follow paths having no discontinuities, i.e., the cathode spots do not favor to cross splits, crevices, scratches or move over the edge of a contact.
  • the shape of contacts provides a submissive path for the cathode spots to travel which develops an ever-lengthening current loop 15, 15a, 15b, to keep the cathode spots spreading outwardly, preventing the formation of the high current mode of the arc.
  • the contribution to the lengthening of the arc as (b), and the distance from the axis as (a), as diagrammatically indicated in FIG. 9.
  • the magnetic force exerted to increase the conducting loop as in FIG. 9, one can vary (a) and (b) to optimize these dimensions to produce the largest magnetic forces for a given current flow. For calculations, the following equation was used:
  • the generally conically-shaped movable contact 18 has continuous spirally-arranged arc-terminal shoulders 30.
  • the shoulder 30 assumes a progressively greater distance a from the axis Y-Y of the contact, and also contributes to the increase of axial length of the arc b by the steady increase from the extremity tip T of contact l8.
  • a vacuum-type circuit interrupter comprising, in combination, means defining an evacuated enclosure, a pair of separable contacts disposed within said evacuated enclosure engageable and disengageable to establish an arc, each of said separable contacts being tact, the configuration is such that the following relationship holds:

Landscapes

  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
  • Arc-Extinguishing Devices That Are Switches (AREA)
US874649A 1969-11-06 1969-11-06 Contact structures for vacuum-type circuit breakers Expired - Lifetime US3683139A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US87464969A 1969-11-06 1969-11-06

Publications (1)

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US3683139A true US3683139A (en) 1972-08-08

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Family Applications (1)

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US874649A Expired - Lifetime US3683139A (en) 1969-11-06 1969-11-06 Contact structures for vacuum-type circuit breakers

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US (1) US3683139A (de)
CH (1) CH522283A (de)
DE (1) DE2053958A1 (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766345A (en) * 1972-12-05 1973-10-16 Allis Chalmers Vacuum interrupter
DE2459270A1 (de) * 1973-12-19 1975-07-03 Westinghouse Electric Corp Vakuumunterbrecher mit schaltkontaktabschirmung
US4451813A (en) * 1981-06-10 1984-05-29 Japan Radio Company, Ltd. Vacuum fuse having magnetic flux generating means for moving arc
US4766274A (en) * 1988-01-25 1988-08-23 Westinghouse Electric Corp. Vacuum circuit interrupter contacts containing chromium dispersions
US4999463A (en) * 1988-10-18 1991-03-12 Square D Company Arc stalling eliminating device and system
US5103069A (en) * 1987-11-07 1992-04-07 Mitsubishi Denki Kabushiki Kaisha Electrode for a vacuum breaker
US20120181254A1 (en) * 2009-09-29 2012-07-19 Schneider Electric Energy France Winding for a contact of a medium-voltage vacuum circuit-breaker with improved arc extinction, and an associated circuit-breaker and vacuum circuit-breaker, such as an ac generator disconnector circuit-breaker

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2812006C2 (de) * 1978-03-18 1982-02-11 Kurt 6368 Bad Vilbel Lenz Elektromechanischer Schaltkontakt zum Schließen und Öffnen elektrischer Stromkreise in Fernmeldeanlagen, insbesondere Fernsprechanlagen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2976382A (en) * 1959-06-29 1961-03-21 Gen Electric Arc extinguishing structure for an electric circuit interrupter
US3182156A (en) * 1961-09-19 1965-05-04 Gen Electric Vacuum-type circuit interrupter
US3275777A (en) * 1964-11-25 1966-09-27 Allis Chalmers Mfg Co Multipoint contacts employing the arc rotating principle
US3327081A (en) * 1964-11-25 1967-06-20 Allis Chalmers Mfg Co Contact with high resistance material insert

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2976382A (en) * 1959-06-29 1961-03-21 Gen Electric Arc extinguishing structure for an electric circuit interrupter
US3182156A (en) * 1961-09-19 1965-05-04 Gen Electric Vacuum-type circuit interrupter
US3275777A (en) * 1964-11-25 1966-09-27 Allis Chalmers Mfg Co Multipoint contacts employing the arc rotating principle
US3327081A (en) * 1964-11-25 1967-06-20 Allis Chalmers Mfg Co Contact with high resistance material insert

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766345A (en) * 1972-12-05 1973-10-16 Allis Chalmers Vacuum interrupter
DE2459270A1 (de) * 1973-12-19 1975-07-03 Westinghouse Electric Corp Vakuumunterbrecher mit schaltkontaktabschirmung
US4451813A (en) * 1981-06-10 1984-05-29 Japan Radio Company, Ltd. Vacuum fuse having magnetic flux generating means for moving arc
US5103069A (en) * 1987-11-07 1992-04-07 Mitsubishi Denki Kabushiki Kaisha Electrode for a vacuum breaker
US4766274A (en) * 1988-01-25 1988-08-23 Westinghouse Electric Corp. Vacuum circuit interrupter contacts containing chromium dispersions
US4999463A (en) * 1988-10-18 1991-03-12 Square D Company Arc stalling eliminating device and system
US20120181254A1 (en) * 2009-09-29 2012-07-19 Schneider Electric Energy France Winding for a contact of a medium-voltage vacuum circuit-breaker with improved arc extinction, and an associated circuit-breaker and vacuum circuit-breaker, such as an ac generator disconnector circuit-breaker
US8835790B2 (en) * 2009-09-29 2014-09-16 Schneider Electric Energy France Winding for a contact of a medium-voltage vacuum circuit-breaker with improved arc extinction, and an associated circuit-breaker and vacuum circuit-breaker, such as an AC generator disconnector circuit-breaker

Also Published As

Publication number Publication date
CH522283A (de) 1972-06-15
DE2053958A1 (de) 1971-05-19

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