US3735075A - Electric circuit breaker having an arcing contact with larger pivot notch than parallel movable contacts - Google Patents

Electric circuit breaker having an arcing contact with larger pivot notch than parallel movable contacts Download PDF

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Publication number
US3735075A
US3735075A US00184799A US3735075DA US3735075A US 3735075 A US3735075 A US 3735075A US 00184799 A US00184799 A US 00184799A US 3735075D A US3735075D A US 3735075DA US 3735075 A US3735075 A US 3735075A
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US
United States
Prior art keywords
contact
arms
circuit breaker
arm
carrier
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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
US00184799A
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English (en)
Inventor
A Kidd
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SMITH D SWITCHGEAR Ltd
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SMITH D SWITCHGEAR Ltd
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/50—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position
    • H01H1/54—Means for increasing contact pressure, preventing vibration of contacts, holding contacts together after engagement, or biasing contacts to the open position by magnetic force
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/12—Contacts characterised by the manner in which co-operating contacts engage
    • H01H1/14—Contacts characterised by the manner in which co-operating contacts engage by abutting
    • H01H1/22—Contacts characterised by the manner in which co-operating contacts engage by abutting with rigid pivoted member carrying the moving contact
    • H01H1/221—Contacts characterised by the manner in which co-operating contacts engage by abutting with rigid pivoted member carrying the moving contact and a contact pressure spring acting between the pivoted member and a supporting member
    • H01H1/226—Contacts characterised by the manner in which co-operating contacts engage by abutting with rigid pivoted member carrying the moving contact and a contact pressure spring acting between the pivoted member and a supporting member having a plurality of parallel contact bars
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/58—Electric connections to or between contacts; Terminals
    • H01H1/5822—Flexible connections between movable contact and terminal
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/58—Electric connections to or between contacts; Terminals
    • H01H1/5833—Electric connections to or between contacts; Terminals comprising an articulating, sliding or rolling contact between movable contact and terminal
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/58—Electric connections to or between contacts; Terminals
    • H01H1/5833—Electric connections to or between contacts; Terminals comprising an articulating, sliding or rolling contact between movable contact and terminal
    • H01H2001/5838—Electric connections to or between contacts; Terminals comprising an articulating, sliding or rolling contact between movable contact and terminal using electrodynamic forces for enhancing the contact pressure between the sliding surfaces

Definitions

  • An electrical circuit breaker or isolator for switching currents of the order of 100,000 amperes, has for each pole thereof, a respective moving contact assembly comprising a plurality of parallel-connected movable contact arms each carrying a respective movable contact engageable with a fixed contact, said arms being of strip metal resiliently mounted side-by-side and substantially parallel to each other in a carrier, each said arm having a V-shaped notch adjacent one end whereby it locates onto an arcuate surface provided by a fixed hinge contact block to which the carrier is hingedly connected, whereby electrical continuity is provided between the arms and the block by direct contact therebetween.
  • An arcing contact arm present in the assembly has the angle of the V-shaped notch in the arcing contact different from that in the other arms to take account of the larger blow-off force occurring between the arcing contact arm and the arcuate surface.
  • a moving contact assembly comprising a plurality of parallel-connected movable contact arms or fingers each carrying a respective movable contact engageable with a fixed contact, so that the current in each pole is split according to the number of arms.
  • the total blowoff force then arising at the abutting contacts for any particular current is reduced in inverse proportion to the number of such arms, as compared with the case where only a single contact arm is present, and consequently the actuating mechanism and structure of the circuit breaker needs only to apply a substantially smaller force to retain the movable contacts in their closed positions, without blow-off occurring.
  • the fixed conductor can, if desired, be formed with slots for accommodating the ends of respective ones of the contact arms or fingers, with a pivot rod extending through the fixed conductor and the ends of the arms or fingers so as to provide hinged connections therewith.
  • Such an arrangement involves a considerable number of machining operations and is therefore expensive.
  • lt is also known to provide a fixed conductor in the form of a hinge contact block which has a V-sectioned channel extending transversely thereof, each of the arms or fingers having on one end thereof an arcuate lobe which locates in the channel, so that the arms each contact the hinge contact block at two opposed locations and are pivotable relative to such block.
  • the hinge contact block can, if desired, be made by extrusion, as also may be stock from which the movable arms or fingers are made.
  • an object of this invention is to provide a parallel-connected novable contact arm arrangement which is suitable for use in electric circuit breakers or in electric isolators wherein such difference can be provided if desired, and which enables the contact arms to be produced simply and inexpensively.
  • the present invention provides an electric circuit breaker or isolator which has, for the or each pole thereof, a respective moving contact assembly comprising a plurality of parallelconnected movable contact arms each carrying a respective movable contact engageable with a fixed contact, characterized in that said arms are of strip metal resiliently mounted side-by-side and substantially parallel to one another in a carrier, each said arm having a V-shaped notch adjacent one end whereby it locates onto an arcuate surface provided by a fixed hinge contact block to which the carrier is hingedly connected,
  • the angle of the .V-shaped notch in such arcing contact arm may be different from that of the other arms, so that the geometry thereof is such as to take into account the fact that the blow-off force occuring between the arcing contact arm and the arcuate surface, upon contact-opening movement of the assembly is considerably higher than that occurring between the other contact arms and said surface.
  • Each movable contact arm is conveniently in the form of a metal pressing, the respective movable contact being secured adjacent the other end thereof, e.g. by high speed brazing which can be effected without softening the contact arms.
  • each of the arms may be mounted in the carrier by a respective locator spring which is shaped, as discussed in our copending Patent application No. 184,800 to provide a loading portion which engages one longitudinal edge of the arm and a pair of limbs extending across the arm one adjacent each side thereof and which locates on a cross member, extending transversely of the arms, of the carrier, adjacent the other longitudinal edge of the arm.
  • the locator springs serve yieldingly and resiliently to mount the movable contact arms in the carrier, and the space between adjacent pairs of the contact arms has one limb of the locator spring of each of said arms extending therethrough, so that these limbs serve effectively to locate the arms relative to one another.
  • each locator spring is conveniently substantially rectangular in configuration, with its shorter sides constituting the limbs, one of the longer sides being the loading portion of the spring, and the other longer side incorporating a formation whereby it locates on thev cross member.
  • Said formation whereby the spring locates on the cross member may be an eye; and such eye can be formed by oppositely-directed hooks provided on the two ends of a single spring-wire length forming the locator spring.
  • the said one of the longer sides of the locator spring which provides the loading portion of the spring is conveniently shaped so that only a short central portion engages with the respective edge of the respective contact arm.
  • each movable contact arm adjacent which the respective movable contact is provided is conveniently shaped to provide a protrusion beneath which engages a lip of the carrier whereby to limit possible movement of the arms under the loading of their springs.
  • FIG. 1 is a cross-section through a preferred embodiment of electric circuit breaker conforming to the invention showing one contact breaker assembly thereof;
  • FIG. 2 is a plan view of the contact breaker assembly of FIG. 1;
  • FIG. 3 is a cross-section on the line 3-3 of FIG. 2;
  • FIG. 4 is a cross-section on the line 4-4 of FIG. 2.
  • the preferred embodiment of the circuit breaker conforming to the invention is a three pole breaker and comprises a generally, rectangular casing (indicated generally at moulded from a suitable electricallyinsulating plastics material the interior of which is divided by appropriate partitions (not shown) to provide three channels (not shown) each of which accommodates a respective contact assembly 1 1.
  • a manual operating mechanism (not shown) of the breaker includes a pivoted lever projecting through a top cover of the casing 10 and connected to the contact assemblies 11 by way of a toggle linkage 12 incorporating a member (not shown) which is supported by a pivoted trip bar (not shown) extending transversely across the three channels.
  • a respective bimetal and electromagnet arrangement (not shown) associated with each contact assembly cooperates with the trip bar to pivot the latter, upon occurrence of a sustained overload (i.e., a sustained passage of current in excess of the rated current of the circuit breaker) or upon occurrence of short circuit conditions (i.e. the passage of a current substantially in excess of the rated current), to release its support and permit collapse of the toggle linkage 12 and thereby trip the breaker.
  • a sustained overload i.e., a sustained passage of current in excess of the rated current of the circuit breaker
  • short circuit conditions i.e. the passage of a current substantially in excess of the rated current
  • the contact assemblies 11 in each of the three channels are substantially identical, and therefore it is only necessary to describe on of them in detail.
  • Such contact assembly 11 comprises, at one end of the channel, a fixed contact block 13 having a fixed contact strip 14 secured to its upper surface so as to extend transversely across the channel.
  • a hinge contact block 15 whose end 16 closest to the fixed contact block 13 has bores 17 at each side thereof each being about three quarters of an inch long and extending transversely of the channel and is shaped on its upper surface to provide a substantially semi-cylindrical upwardly-directed bearing surface 18 disposed so that its axis extends transversely of the channel substantially concentrically of the bores 17.
  • the bores accommodate respective hinge pins 19 the ends 20, 21 of which protrude from the hinged contact block 15 and serve pivotally to connect, to said hinge contact block 15, an inverted-U-sectioned or invertedchannel-sectioned movable contact arm carrier 22, with the ends 20, 21 of the rod 19 engaging into apertures 23, 24 in respective side walls 25, 26 of said carrier 22.
  • each of such movable contact arms 27 is in the form of a metal pressing, of copper strip, for example of approximately three-sixteenths of an inch in thickness, generally rectangular in configuration, and having the respective movable contact 28 secured to one edge thereof, adjacent to one end, e.g. by high speed brazing.
  • each such strip Adjacent to the other end, each such strip has a V- shaped notch 31 cut therein, from the same edge, whereby the arm 27 locates on and makes electrical contact with the bearing surface 18 of the hinge contact block 15.
  • the fact that the movable contacts 28 can be secured to their respective arms 27 by high speed brazing has the advantage that it can be effected without causing the material of the arm 27 to anneal and become soft. Any softening of the movable contact arms 27 is to be avoided, of course, since impacts of substantial force occur in the operation of the breaker, and this would cause distortion of the arms 27.
  • a cross member 32 thereof extends transversely across the carrier 22 between the side walls 25, 26 thereof at a level below the lower edges of the contact arms 27, which lower edges are, of course, the edges in which the V-shaped notches 31 are provided and on which the fixed contacts 28 are secured.
  • the arms 27 are mounted in the carrier 22 by way of respective locator springs 33 which engage with the upper edges of the respective contact arms 27 and locate on the cross member 32.
  • Each such locator spring 33 (FIGS. 3 and 4) is made from a length of strong spring wire bent to a substantially rectangular configuration.
  • One of the longer sides thereof is a loading portion 34 which is slightly bowed along its length and provides a linear middle section 35 which abuts against a part of the upper edge of the respective contact arm 27.
  • the two shorter sides of the spring constitute guide limbs 36, 37 which extends across the respective contact arm 27, one against each side of the contact arm 27 and join with the other longitudinal side of the spring which is provided with a formation 39 is provided by the ends of the length of wire, which ends are curved to form oppositely directed hooks 40, ill which together form an eye around the cross member 32.
  • each contact arm 27 is formed with a protrusion 42 which engages with a lip 43 on the carrier 22 to limit movement of the arm 27 under the influence of its spring 33.
  • circuit breaker effectively operates in the same way as prior known comparable constructions of breaker.
  • the toggle linkage 12 With the operating handle in the on position, the toggle linkage 12 is extended to press the carriers 22 downwards, so that the movable contacts 28 all engage the fixed contact strip 14 and are loaded thereagainst by their respective locator springs 33.
  • the moving contact arms 27 in the contact assembly of each pole serve to divide the current passing in said pole, with the consequent advantage of reduced blowoff force (as already discussed herein) at the contacts so that the force necessary to hold the moving contacts 29 in adequate engagement with the fixed contact strip 14 is substantially less than in the case where each pole has a smaller number of contact arms 27 and respective movable contacts 28, and the components of the circuit breaker can be of lesser dimensions and strength than in the latter instance.
  • the toggle 12 Upon occurrence of a sustained overload or short circuit (as above explained) the toggle 12 is broken, the carriers 27 are displaced away from the fixed contacts 14 to open the circuits through the circuit breaker, and the handle is moved to the tripped position.
  • Each contact arm 27 has a braid 45 welded thereto adjacent its said other end and a loop 46 of the braid 45 is attached to the hinge contact block by means of a screw 47. Screws 47 also fasten a length of L-section angle iron 48 to the hinge contact block 15. This angle iron has its longer free ends 49 extending beneath the arms 27.
  • the braid 45 diverts some current from the edges of the notches 31 and so reduces the blow-off force at surface 18.
  • the angle iron 48 tends to attract the contact arms 27 when current is flowing therein and so tends to oppose the blow-off forces.
  • the circuit breaker may be constructed with components of lesser dimensions and/or strength than has hitherto been necessary and also has other advantages.
  • the arrangement of springs 33 providing for one limb 36, 37 thereof alongside each side of the respective contact arm 27 achieves proper location of the contact arms 27 relative to one another, so that they lie side-by-side in parallel disposition in a very simple and convenient manner which is easy to assemble.
  • the form of the contact arm 27 is such that they can be manufactured readily and relatively inexpensively by simple pressing operations as compared with the expensive castings or extruded sections which have hitherto been conventionally employed for movable contact arms.
  • An electric circuit breaker or isolator which has, for the or each pole thereof, a respective moving contact assembly comprising: a plurality of parallelconnected movable contact arms each carrying a respective movable contact engageable with a fixed contact, the contact arms being of strip metal and being resiliently mounted side-by-side and substantially parallel to each other in a carrier, each contact arm having a V-shaped notch adjacent one end for locating onto an arcuate surface provided by a fixed hinge contact block to which the carrier is hingedly connected, electrical continuity being provided between the contact arms and the contact block by direct contact therebetween, one of the contact arms being an arcing contact arm, the angle of the V-shaped notch therein being different from that of the other arms.
  • each of the contact arms being mounted in the carrier by a respective locator spring shaped to provide a loading portion which engages one longitudinal edge of the contact arm and a pair of limbs extending across the contact arm one adjacent each side thereof and which locates on a cross member, extending transversely of the arms, of
  • each locator spring being substantially rectangular in configuration, with its shorter sides constituting the limbs, one of spective contact arm. it ⁇ .
  • a circuit breaker as claimed in claim 1 a length of L-section angle iron being attached to the hinge contact block and one web thereof extending below the contact arms so that when current is passing through the arms a magnetic attractive force is set up tending to draw the arms towards the one web and thus the notches into better contact with the arcuate surface.

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  • Breakers (AREA)
  • Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)
US00184799A 1970-10-29 1971-09-29 Electric circuit breaker having an arcing contact with larger pivot notch than parallel movable contacts Expired - Lifetime US3735075A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5135370 1970-10-29

Publications (1)

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US3735075A true US3735075A (en) 1973-05-22

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US00184799A Expired - Lifetime US3735075A (en) 1970-10-29 1971-09-29 Electric circuit breaker having an arcing contact with larger pivot notch than parallel movable contacts

Country Status (5)

Country Link
US (1) US3735075A (en:Method)
DE (1) DE2152643B2 (en:Method)
FR (1) FR2110155A5 (en:Method)
GB (1) GB1312156A (en:Method)
IT (1) IT940999B (en:Method)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4162467A (en) * 1977-06-16 1979-07-24 Westinghouse Electric Corp. Circuit breaker contact structure
DE3018254A1 (de) * 1979-06-07 1980-12-18 Westinghouse Electric Corp Selbstschalter mit lichtbogenloescher
US4736114A (en) * 1985-02-23 1988-04-05 Sachsenwerk Licht- Und Kraft-Aktiengesellshaft Electrical switching system and method to switch this system
US4871889A (en) * 1988-09-21 1989-10-03 Siemens Energy & Automation, Inc. Arcing contact assembly for a circuit breaker
US4926019A (en) * 1988-09-08 1990-05-15 Siemens Energy & Automation, Inc. Moving copper pivot
US5004875A (en) * 1988-10-11 1991-04-02 Siemens Energy & Automation, Inc. Stored energy contact operating mechanism
US5296660A (en) * 1992-02-07 1994-03-22 Merlin Gerin Auxiliary shunt multiple contact breaking device
US5519180A (en) * 1994-08-08 1996-05-21 General Electric Company Method for controlling contact depression for high ampere-rated circuit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU186337U1 (ru) * 2018-09-05 2019-01-16 Закрытое акционерное общество "Производственное объединение Электротехник" Выключатель-разъединитель

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2821594A (en) * 1954-02-04 1958-01-28 Merlin Gerin Electrodynamic compensation device for pressure contacts
US3041431A (en) * 1959-06-26 1962-06-26 Fed Pacific Electric Co Circuit breaker
US3365561A (en) * 1966-11-21 1968-01-23 Gen Electric Multiple finger type current-carrying contact arm pivot assembly
US3402274A (en) * 1965-10-01 1968-09-17 Square D Co Contact structure for a power circuit breaker
FR1552452A (en:Method) * 1967-02-08 1969-01-03
US3560683A (en) * 1968-01-24 1971-02-02 Westinghouse Electric Corp Circuit breaker with improved contact structure

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2821594A (en) * 1954-02-04 1958-01-28 Merlin Gerin Electrodynamic compensation device for pressure contacts
US3041431A (en) * 1959-06-26 1962-06-26 Fed Pacific Electric Co Circuit breaker
US3402274A (en) * 1965-10-01 1968-09-17 Square D Co Contact structure for a power circuit breaker
US3365561A (en) * 1966-11-21 1968-01-23 Gen Electric Multiple finger type current-carrying contact arm pivot assembly
FR1552452A (en:Method) * 1967-02-08 1969-01-03
US3560683A (en) * 1968-01-24 1971-02-02 Westinghouse Electric Corp Circuit breaker with improved contact structure

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4162467A (en) * 1977-06-16 1979-07-24 Westinghouse Electric Corp. Circuit breaker contact structure
DE3018254A1 (de) * 1979-06-07 1980-12-18 Westinghouse Electric Corp Selbstschalter mit lichtbogenloescher
US4736114A (en) * 1985-02-23 1988-04-05 Sachsenwerk Licht- Und Kraft-Aktiengesellshaft Electrical switching system and method to switch this system
US4926019A (en) * 1988-09-08 1990-05-15 Siemens Energy & Automation, Inc. Moving copper pivot
US4871889A (en) * 1988-09-21 1989-10-03 Siemens Energy & Automation, Inc. Arcing contact assembly for a circuit breaker
US5004875A (en) * 1988-10-11 1991-04-02 Siemens Energy & Automation, Inc. Stored energy contact operating mechanism
US5296660A (en) * 1992-02-07 1994-03-22 Merlin Gerin Auxiliary shunt multiple contact breaking device
US5519180A (en) * 1994-08-08 1996-05-21 General Electric Company Method for controlling contact depression for high ampere-rated circuit

Also Published As

Publication number Publication date
GB1312156A (en) 1973-04-04
DE2152643A1 (de) 1972-05-04
FR2110155A5 (en:Method) 1972-05-26
DE2152643B2 (de) 1976-07-01
IT940999B (it) 1973-02-20

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