US3721788A - Locator spring structure for contact assembly of high voltage electrical circuit breakers - Google Patents

Locator spring structure for contact assembly of high voltage electrical circuit breakers Download PDF

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Publication number
US3721788A
US3721788A US00184800A US3721788DA US3721788A US 3721788 A US3721788 A US 3721788A US 00184800 A US00184800 A US 00184800A US 3721788D A US3721788D A US 3721788DA US 3721788 A US3721788 A US 3721788A
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United States
Prior art keywords
carrier
contact
arms
arm
spring
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Expired - Lifetime
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US00184800A
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English (en)
Inventor
A Kidd
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.)
Dorman Smith Switchgear Ltd
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Dorman Smith Switchgear Ltd
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Publication of US3721788A publication Critical patent/US3721788A/en
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    • 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
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/30—Means for extinguishing or preventing arc between current-carrying parts
    • H01H9/38—Auxiliary contacts on to which the arc is transferred from the main contacts
    • H01H9/383—Arcing contact pivots relative to the movable contact assembly

Definitions

  • ABSTRACT An electrical circuit breaker or isolator, intended to carry high currents of the order of 100,000 amperes, has for each pole a respective moving contact assembly comprising a plurality of parallel-connected movable contact arms each carrying a respective movable contact, said arms being of strip metal, to reduce manufacturing costs, are disposed side-by-side and substantially parallel in a carrier, each said arm being mounted in the carrier by a respective locator spring shaped 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 serving yieldingly and resiliently to mount the movable contact arms in the carrier and the limbs of the springs effectively locating the arms relative to one another.
  • a moving contact assembly comprising a plurality of parallelconnected movable contact arms or fingers each carry ing 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 blow-off force then arising 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 position, without blow-off occurring.
  • An object of the present invention is to provide a parallel-connected movable contact arrangement of the above-mentioned kind, which is particularly suitable for electric circuit breakers but may also be employed in electrical isolators, wherein relative location of and loading of the arms within a carrier therefore is achieved in a simple and convenient manner which permits the arms to be substantially thinner than has previously been necessary, so that a large number thereof can be employed.
  • 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 parallel-connected movable contact arms each carrying a respective movable contact engageable with a fixed contact, characterized in that the arms are of strip metal, are disposed side-by-side and substantially parallel in a carrier, each the arm being mounted in the carrier by a respective locator spring which is shaped 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 the 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 the cross member.
  • the 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 aforementioned 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 is conveniently in the form of a metal pressing, the respective movable contact being secured adjacent one end thereof, e.g. by high speed brazing which can be effected without softening the contact arm.
  • Each such arm may then be formed with a V-shaped notch adjacent its other end whereby it locates onto an arcuate surface provided by a fixed hinge contact block to which the carrier is hingedly connected.
  • 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 assembly thereof;
  • FIG. 2 is a plan view of the contact assembly of FIG.
  • 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 electrically insulating 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 11.
  • 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 ofa 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 ofa 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 one 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 hingep pins 19 the ends 20, 21 of which protrude from the hinged contact block 15 and serves pivotally to connect to said hinge contact block 15, an inverted-U-sectioned, or inverted-channel-sectioned movable contact arm carrier 22, with the ends 20, 21 of the pins 19 engaging into apertures 23, 24 in respective side walls 25, 26 of said carrier 22.
  • Each of the 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 hinged 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 movable 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 locator spring 33 (see 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 extend 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 locating the spring 33 on the cross member 32 of the carrier 22.
  • the formation 39 is provided by the ends of the length of wire, which ends are curved to form oppositely directed hooks 40, 41 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) so that the force necessary to hold the moving contacts 28 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 arms 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.
  • the construction of the invention 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 arms 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.
  • the contact arrangement 1 1 of the invention can be employed in an electrical isolator, the construction being such as to provide two opposed carriers 22 with their contact arms 27 facing one another to provide therebetween a gap for accommodating a withdrawable conductor leading, for example, to an electrical component, the arrangement being such that relative movement between the contact arms 27 and the conductor is possible for withdrawing the latter to isolate the electrical component.
  • thecarrier In an electrical circuit breaker or isolator, thecarrier, the carrier having a cross-member extending transversely of and spaced from one side of the contact arms, each contact arm constituting a strip in electrical contact with the contact block adjacent one of its ends, a single loop helical locator spring serving to mount each contact arm in the carrier, the locator spring having its ends engaged with the cross-member of the carrier and extending around the contact arm and having a loading portion extending diagonally across a longitudinal edge of the contact arm and having limbs extending one adjacent each side of the contact arm, the loading portion of the locator spring biassing the arm towards the cross-member and the limbs acting as spacers between adjacent contact arms.
  • each locator spring is 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 the cross-member.
  • each movable contact arm is formed with a V- shaped notch adjacent its other end whereby it locates onto an arcuate surface provided by a fixed hinge contact block to which the carrier is hingedly connected.
  • each movable contact arm is 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 spring.

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US00184800A 1970-10-22 1971-09-29 Locator spring structure for contact assembly of high voltage electrical circuit breakers Expired - Lifetime US3721788A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5009470 1970-10-22

Publications (1)

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US00184800A Expired - Lifetime US3721788A (en) 1970-10-22 1971-09-29 Locator spring structure for contact assembly of high voltage electrical circuit breakers

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US (1) US3721788A (show.php)
DE (1) DE2151903C3 (show.php)
FR (1) FR2111532A5 (show.php)
GB (1) GB1312157A (show.php)
IT (1) IT940998B (show.php)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111341615A (zh) * 2020-03-26 2020-06-26 贵州泰永长征技术股份有限公司 一种特殊的浮动式静触头组件装置结构

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6147035A (ja) * 1984-08-10 1986-03-07 富士電機株式会社 回路遮断器の接触子構造
CZ300885B6 (cs) * 2002-01-22 2009-09-02 Oez S.R.O. Záves tažné pružiny, zejména pro silové pružiny u spínacích prístroju
CZ300886B6 (cs) * 2002-03-25 2009-09-02 Oez S.R.O. Vybavovací ústrojí, zejména spínacích mechanismu jisticu a odpínacu

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2689896A (en) * 1951-11-28 1954-09-21 Cutler Hammer Inc Shock resistant electric switch
US2788421A (en) * 1953-05-12 1957-04-09 Westinghouse Electric Corp Circuit breaker contact structure
US2933580A (en) * 1958-05-06 1960-04-19 Joe Davidson Pivotally balanced members
US2945927A (en) * 1959-03-20 1960-07-19 Mason Electric Corp Rotary switch with common advancing and pressure springs
US2962573A (en) * 1958-10-01 1960-11-29 Gen Electric Electric circuit interrupter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2689896A (en) * 1951-11-28 1954-09-21 Cutler Hammer Inc Shock resistant electric switch
US2788421A (en) * 1953-05-12 1957-04-09 Westinghouse Electric Corp Circuit breaker contact structure
US2933580A (en) * 1958-05-06 1960-04-19 Joe Davidson Pivotally balanced members
US2962573A (en) * 1958-10-01 1960-11-29 Gen Electric Electric circuit interrupter
US2945927A (en) * 1959-03-20 1960-07-19 Mason Electric Corp Rotary switch with common advancing and pressure springs

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111341615A (zh) * 2020-03-26 2020-06-26 贵州泰永长征技术股份有限公司 一种特殊的浮动式静触头组件装置结构

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Publication number Publication date
GB1312157A (en) 1973-04-04
FR2111532A5 (show.php) 1972-06-02
IT940998B (it) 1973-02-20
DE2151903B2 (de) 1974-09-05
DE2151903C3 (de) 1975-04-30
DE2151903A1 (de) 1972-04-27

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