US3699290A - Electric circuit breakers - Google Patents

Electric circuit breakers Download PDF

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Publication number
US3699290A
US3699290A US189879A US3699290DA US3699290A US 3699290 A US3699290 A US 3699290A US 189879 A US189879 A US 189879A US 3699290D A US3699290D A US 3699290DA US 3699290 A US3699290 A US 3699290A
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US
United States
Prior art keywords
arcing
movable
contacts
contact
circuit breaker
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
US189879A
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English (en)
Inventor
George Caton
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.)
Yorkshire Switchgear and Engineering Co Ltd
Original Assignee
Yorkshire Switchgear and Engineering 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 Yorkshire Switchgear and Engineering Co Ltd filed Critical Yorkshire Switchgear and Engineering Co Ltd
Application granted granted Critical
Publication of US3699290A publication Critical patent/US3699290A/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
    • H01H33/02—Details
    • H01H33/04—Means for extinguishing or preventing arc between current-carrying parts
    • H01H33/18—Means for extinguishing or preventing arc between current-carrying parts using blow-out magnet
    • H01H33/185—Means for extinguishing or preventing arc between current-carrying parts using blow-out magnet using magnetisable elements associated with the contacts
    • 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
    • H01H33/02—Details
    • H01H33/04—Means for extinguishing or preventing arc between current-carrying parts
    • H01H33/12—Auxiliary contacts on to which the arc is transferred from the main contacts
    • 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
    • H01H33/02—Details
    • H01H33/04—Means for extinguishing or preventing arc between current-carrying parts
    • H01H33/14—Multiple main contacts for the purpose of dividing the current through, or potential drop along, the arc

Definitions

  • ABSTRACT The invention concerns a fluid-immersed electric circuit breaker comprising first. an second sets of fixed contacts each said set comprising a fixed main contact and a fixed arcing contact, an insulating carrier structure, a movable bridging contact carried on said insulating carrier structure and having first and second sets of movable contacts each set comprising a movable main contact and a movable arcing contact, said movable main and arcing contacts being movable to engage respective ones of said fixed main and arcing contacts, a fluid-filled arc-quenching chamber housing said movable contact sets and having a restricted outlet positioned so that under pressure of gas generated by arcing within the chamber a stream of said fluid under pressure is directed across an arcing path between one of said fixed arcing contacts and the assurrounded by at least one loop of ferromagnetic material which has been found to improve quenching of the arc.
  • Electric circuit breakers having a movable bridging contact cooperating with a pair of fixed contacts to make and break a circuit between the fixed contacts.
  • the bridging contact is carried by an insulating carrier structure, and for each fixed contact the ridging contact has a contact set comprising a movable main contact and a movable auxiliary arcing contact electrically connected to each, the two contact sets being electrically connected.
  • the movable main and auxiliary contacts cooperate respectively with a main contact and an auxiliary arcing contact together making up the fixed contact.
  • the arrangement is such that the arcing contacts are arranged to break this connection after the main contacts, and to make the connection before the main contacts, so that arcing is confined to the arcing contacts.
  • These arcing contacts are housed in an arc-quenching chamber filled with a fluid suitable for arc-quenching purposes, a commonly used fluid being oil.
  • the arcing contacts of both contact sets are housed in a common arc-quenching chamber, and the arrangement is usually such that the arcing contacts associated with one fixed contact are caused to arc before those of the other fixed contact, so generating gas, the pressure of which forces a stream of fluid across the arcing path of the other fixed contact to a restricted outlet from the arc-quenching chamber to assist in quenching the arc.
  • the object of the present invention is to provide improved arc quenching in a circuit breaker of this type.
  • a fluid-immersed electric circuit breaker includes a pair of fixed contacts each comprising main contacts and arcing contacts, a movable bridging contact carried on an insulating carrier structure and having two sets of movable main and arcing contacts, the movable main and arcing contacts of each set being movable to engage respectively the main and arcing contacts of a respective one of the fixed contacts, the movable arcing contacts being disposed in an arc-quenching chamber having a restricted outlet positioned so that under pressure of gas generated by arcing within the chamber a stream of fluid under pressure is directed across the arcing path between at least one pair of fixed and movable arcing contacts, and one or more of the arcing paths being surrounded by at least one loop of ferromagnetic material.
  • This field includes loops closely surrounding the arc path and each loop acts to constrict the arc toward the minimum path between the fixed and movable arcing contacts. Furthermore, the complex interacting fields created by this multiplicity of loops during the movement of the bridging contact cause a rapid oscillatory disturbance of the arc within the path and produces considerable oil and gas turbulence within the region in and around the arc path. This turbulence assists in cooling the arc and also contributes towards the instability of the arc so that it is more sensitive to de-ionization by the stream of fluid directed across the path of the arc. The arc is therefore quenched more easily than with existing circuit breakers.
  • a given arcing current can be handled by a smaller circuit breaker than is used at the moment, or conversely a circuit breaker according to the invention of comparable dimensions to a conventional circuit breaker will be able to handle a higher arcing current at the same or at a higher voltage than the conventional circuit breaker.
  • the circuit breaker- is such that arcing occurs over a first pair of fixed and movable arcing contacts before arcing occurs over the second pair of fixed and movable arcing contacts, and the arc-quenching chamber is shaped so that the gas generated at the first pair of arcing contacts directs a stream of oil across the arcing path between the second pair of arcing contacts, each pair of arcing contacts being surrounded by a closed loop or loops of ferromagnetic material.
  • each pair of arcing contacts may be used, it is desirable to provide two or more loops.
  • all the loops associated with a pair of arcing contacts have a common ferromagnetic member or are externally joined together by ferromagnetic members.
  • All or any of the loops of ferromagnetic material may be either closed or open, i.e. the ferromagnetic path around the arc may be continuous or it may be interrupted by one .or more gaps.
  • the invention is effective as long as there is sufficient ferromagnetic material to enable the arcing current to induce a magnetic field affecting the stability of the arc.
  • Movable bridging contact assemblies conventionally known as arc traps, for circuit breakers of the type'with which the invention deals provide two movable contact sets, each contained by a laminar structure, usually including outer conductive plates constituting the movable main contacts, insulating layers to the insides of these plates and laminations of fiber or other are resistant material to the inside of the insulating layers, there being a space in the laminar structure to receive the fixed arcing contacts.
  • the movable arcing contacts are housed between, and conductively connected to, the outer conductive plates.
  • the ferromagnetic loop associated with a laminated structure movable contact assembly comprises ferromagnetic strips to the outside of the outer conductive plates, the ferromagnetic strips being joined by ferromagnetic bolts passing transversely through the laminations of the arc trap assembly.
  • the bolts can be made quite heavy and they are found to increase the bursting strength of the movable contact quite considerably.
  • FIG. 1 is a section through the center line of the movable bridging contact of the circuit breaker
  • FIG. 2 is a section on the line A-A of FIG. 1;
  • FIG. 3 shows a part section of a fixed contact of the circuit breaker with part of the bridging contact in the closed position.
  • the circuit breaker comprises a movable bridging contact 1 carried by an insulating carrier structure 2 and cooperating with a pair of fixed contact assemblies 3 and 4 to make and break a circuit.
  • Each fixed contact assembly has a main contact comprising copper fingers 5 and 6 and an auxiliary arcing contact in the form of an elongated electrode 7 which may have a tungsten copper tip.
  • the bridging contact comprises two similar contact sets la and 1b, and only contact lawill be described in detail.
  • This comprises two outer copper conducting plates 8 and 9 constituting a main contact, further conducting plates 10 and 11, insulating plates 12 and 13 and fiber arc trap plates 14 and 15 which are shaped to form space 16 to accept the electrode 7.
  • the plates 14 and 15 are also shaped to accept arcing contacts 17 and 18 electrically connected to plates 8 and 9 by conductors 19 and 20.
  • This laminated structure is held together by steel plates 21 and 22 outside the copper plates 8 and 9 and bolts 23 to 27 extending between the plates so that the plates and bolts together form a closed loop of ferromagnetic material around the arcing contacts 17 and 18.
  • the arcing contacts 17 and 18 of the contact set la lie at one end of an arc-quenching chamber 29, and the arcing contacts of the other contact set lb lie at the other end of the arc quenching chamber.
  • the chamber is filled with oil, and has passages 30 to 33 for passage of oil. Passages 32 and 33 intersect the line of an arc struck between electrode 7 of fixed contact 4 and arc ing contacts 17 and 18 of contact set 1a.
  • the arrangement of the contacts is such that when the circuit is to be broken the main contacts such as 5 and 6 of both fixed contacts leave the main contacts-8 and 9 of the respective movable ridging contact set before the arcing contacts of the movable and fixed contacts part.
  • the bolts 23 to 27 impart bursting strength to the movable contacts 1a and 1b so that the circuit breaker can withstand substantial pressures.
  • a ferromagnetic plate 34 joins together the ferromagnetic loops associated with the contact sets 1a and 1b.
  • a fluid-immersed electric circuit breaker comprising first and second sets of fixed contacts each said set comprising a fixed main contact and a fixed arcing contact, an insulating carrier structure, a movable bridging contact carried on said insulating carrier structure and having first and second sets of movable contacts each set comprising a movable main contact and a movable arcing contact, said movable main and arcing contacts being movable toengage respective ones of said fixed main and arcing contacts, a fluid-filled arc-quenching chamber housing said movable contact sets and having a restricted outlet positioned so that under pressure of gas generated by arcing within the chamber a stream of said fluid under pressure is directed across an arcing path between one of said fixed arcing contacts and the associated one of said movable arcing contacts, and at least one loop of ferromagnetic material surrounding said arcing path.
  • a circuit breaker as claimed in claim 1 which is such that arcing occurs between said fixed and movable arcing contacts of said first contact sets before arcing occurs between said fixed and movable arcing contacts of said second contact sets, and said arc-quenching chamber is shaped so that gas generated during arcing at said first contact sets directs a stream of said fluid across the arcing path at said second contact sets, said arcing contacts in each contact set being surrounded by a closed loop or loops of ferromagnetic material.
  • laminations of are resistant material to the inside of said insulating layers, wherein said ferromagnetic loop associated with said arcing contacts of each set comprises ferromagnetic strips to the outside of said outer conductive plates and ferromagnetic bolts joining said ferromagnetic strips and passing transversely through

Landscapes

  • Arc-Extinguishing Devices That Are Switches (AREA)
  • Breakers (AREA)
US189879A 1970-11-13 1971-10-18 Electric circuit breakers Expired - Lifetime US3699290A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB5415270 1970-11-13
AU40091/72A AU464742B2 (en) 1970-11-13 1972-03-16 Improvements in electric circuit breakers

Publications (1)

Publication Number Publication Date
US3699290A true US3699290A (en) 1972-10-17

Family

ID=25624980

Family Applications (1)

Application Number Title Priority Date Filing Date
US189879A Expired - Lifetime US3699290A (en) 1970-11-13 1971-10-18 Electric circuit breakers

Country Status (6)

Country Link
US (1) US3699290A (de)
AU (1) AU464742B2 (de)
CH (1) CH539941A (de)
DE (1) DE2156400A1 (de)
GB (1) GB1315026A (de)
NL (1) NL7115495A (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1843615A (en) * 1928-09-19 1932-02-02 Westinghouse Electric & Mfg Co Circuit breaker
DE661181C (de) * 1931-04-01 1938-06-13 Stalturbine G M B H Fluessigkeitsschalter mit mehreren in Druckkammern angeordneten und in Reihe geschalteten Unterbrechungsstellen
US2175878A (en) * 1937-06-28 1939-10-10 Gen Electric Yielding contact unit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1843615A (en) * 1928-09-19 1932-02-02 Westinghouse Electric & Mfg Co Circuit breaker
DE661181C (de) * 1931-04-01 1938-06-13 Stalturbine G M B H Fluessigkeitsschalter mit mehreren in Druckkammern angeordneten und in Reihe geschalteten Unterbrechungsstellen
US2175878A (en) * 1937-06-28 1939-10-10 Gen Electric Yielding contact unit

Also Published As

Publication number Publication date
GB1315026A (en) 1973-04-26
CH539941A (fr) 1973-09-14
AU4009172A (en) 1973-09-20
AU464742B2 (en) 1975-09-04
DE2156400A1 (de) 1972-05-18
NL7115495A (de) 1972-05-16

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