CIRCUIT BREAKER FOR ISOLATING AN ELECTRICAL CIRCUIT

Abstract

A circuit breaker includes a switching unit for interrupting an electrical circuit. The switching unit has a stationary fixed contact and a moving contact to be moved relative to the fixed contact and to be switched from a closed position to an open position. A quenching device for quenching an arc when the contacts are opened includes a prechamber for guiding the arc from the contacts to a quenching chamber. The prechamber has two insulating side walls and a pair of arc guide rails situated therebetween. A ferromagnetic shaped part is disposed on each of the side walls, and a permanent magnet is disposed in the region of the fixed contact. The magnetic field of the permanent magnet guides the arc along one of the arc guide rails.

Claims

1. A circuit breaker, comprising: a switching unit for interrupting an electrical circuit, said switching unit including: a stationary fixed contact; a moving contact configured to be moved relative to said fixed contact and to be transferred from a closed position to an open position; a quenching device for quenching an arc produced upon opening said contacts, said quenching device including a quenching chamber and a prechamber for guiding the arc from said contacts to said quenching chamber, said prechamber having two insulating side walls and a pair of arc guide rails disposed between said side walls; ferromagnetic shaped parts each disposed on a respective one of said side walls; and a permanent magnet disposed in a region of said fixed contact, said permanent magnet forming a magnetic field guiding the arc along one of said arc guide rails.

2. The circuit breaker according to claim 1, which further comprises two shaped magnets for guiding the arc in addition to said permanent magnet.

3. The circuit breaker according to claim 1, wherein said one arc guide rail is guided to said fixed contact, and said one arc guide rail has a curved or bent profile from said fixed contact toward said quenching chamber.

4. The circuit breaker according to claim 3, wherein said quenching chamber has a first side wall, said one arc guide rail connects said fixed contact to said first side wall of said quenching chamber, and said one arc guide rail has a convex profile starting from said fixed contact.

5. The circuit breaker according to claim 4, wherein said first side wall is formed by a magnet yoke of a short-circuit release.

6. The circuit breaker according to claim 3, wherein said permanent magnet is disposed in a region of the bend or curvature of said one arc guide rail.

7. The circuit breaker according to claim 6, wherein said permanent magnet is disposed radially on an inside of the bend or curvature.

8. The circuit breaker according to claim 1, wherein said ferromagnetic shaped parts each have an electrical insulation at end sides oriented toward said quenching chamber.

9. The circuit breaker according to claim 8, wherein said shaped parts are insert parts encapsulated by injection-molding with said electrical insulation in the region of the end sides.

10. The circuit breaker according to claim 1, wherein said quenching chamber is constructed as a deionization chamber with an arc splitter stack.

11. The circuit breaker according to claim 1, which further comprises: a pivotable switching arm, said moving contact being disposed on said pivotable switching arm; a manual operating mechanism coupled to said pivotable switching arm for manually adjusting said pivotable switching arm between the open position and the closed position; and a release mechanism coupled to said pivotable switching arm for automatically returning said pivotable switching arm to the open position when a release condition occurs.

12. The circuit breaker according to claim 11, which further comprises a switching housing, said switching unit, said release mechanism and said manual operating mechanism being at least partially accommodated together in said switching housing.

13. A circuit breaker, comprising: a switching unit for interrupting an electrical circuit, said switching unit including: a stationary fixed contact; a moving contact configured to be moved relative to said fixed contact and to be transferred from a closed position to an open position; a quenching device for quenching an arc produced upon opening said contacts, said quenching device including a quenching chamber and a prechamber for guiding the arc from said contacts to said quenching chamber, said prechamber having two insulating side walls and a pair of arc guide rails disposed between said side walls; and shaped magnets each disposed on a respective one of said side walls, said shaped magnets together forming a magnetic field guiding the arc along one of said arc guide rails.

14. The circuit breaker according to claim 13, wherein said one arc guide rail is guided to said fixed contact, and said one arc guide rail has a curved or bent profile from said fixed contact toward said quenching chamber.

15. The circuit breaker according to claim 14, wherein said quenching chamber has a first side wall, said one arc guide rail connects said fixed contact to said first side wall of said quenching chamber, and said one arc guide rail has a convex profile starting from said fixed contact.

16. The circuit breaker according to claim 15, wherein said first side wall is formed by a magnet yoke of a short-circuit release.

17. The circuit breaker according to claim 14, wherein said permanent magnet is disposed in a region of the bend or curvature of said one arc guide rail.

18. The circuit breaker according to claim 17, wherein said permanent magnet is disposed radially on an inside of the bend or curvature.

19. The circuit breaker according to claim 13, wherein said shaped magnets each have an electrical insulation at end sides oriented toward said quenching chamber.

20. The circuit breaker according to claim 19, wherein said shaped magnets are insert parts encapsulated by injection-molding with said electrical insulation in the region of the end sides.

21. The circuit breaker according to claim 13, wherein said quenching chamber is constructed as a deionization chamber with an arc splitter stack.

22. The circuit breaker according to claim 13, which further comprises: a pivotable switching arm, said moving contact being disposed on said pivotable switching arm; a manual operating mechanism coupled to said pivotable switching arm for manually adjusting said pivotable switching arm between the open position and the closed position; and a release mechanism coupled to said pivotable switching arm for automatically returning said pivotable switching arm to the open position when a release condition occurs.

23. The circuit breaker according to claim 22, which further comprises a switching housing, said switching unit, said release mechanism and said manual operating mechanism being at least partially accommodated together in said switching housing.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0058] FIG. 1 is a diagrammatic, perspective view of a circuit breaker;

[0059] FIG. 2 is a perspective view of a switching unit of the circuit breaker including a contact system and including a quenching unit which has a prechamber with two side walls and also a quenching chamber;

[0060] FIG. 3 is a perspective view of the switching unit of FIG. 2 with a side wall removed;

[0061] FIG. 4 is a perspective view of an alternative embodiment of the switching unit including a manual operating mechanism and including a release mechanism of the circuit breaker; and

[0062] FIG. 5 is an enlarged, fragmentary, elevational view of the embodiment according to FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

[0063] Referring now in detail to the figures of the drawings, in which parts and sizes which correspond to one another are always provided with the same reference signs, and first, particularly, to FIG. 1 thereof, there is seen a circuit breaker 2 for interrupting an electrical circuit. To this end, the circuit breaker 2 has a switching unit 4 which is explained in more detail with reference to FIGS. 2 to 5. The circuit breaker 2 furthermore has a switching housing 6 composed of an insulating material.

[0064] The circuit breaker 2 is preferably constructed in the manner of a rail-mounted device. The switching housing 6 accordingly has a shaping which is characteristic of devices of this kind and is stepped in a symmetrical manner in relation to a front side 8. A pivot lever 12 of a manual operating mechanism 14 (FIG. 4, FIG. 5) projects out of the switch housing 6 on a projecting central part 10 of the front side 8 for manual operation of the switching unit 4. The circuit breaker 2 is provided with a latching groove 18, which is typical of rail-mounted devices, for latching on a mounting rail, in particular on a top-hat rail, on a rear side 16 which is situated opposite the front side 8. Two end sides 20 of the switch housing 6 are disposed perpendicular to the front side 8 and the rear side 16, the circuit breaker 2 being lined up along the two end sides in the installed or assembled state of a rail-mounted device.

[0065] FIGS. 2 and 3 show a first and a second embodiment of the switching unit 4, 4. The switching unit 4, 4 has a mechanical contact system having a stationary fixed contact 22 and having a moving contact 24 which can move relative to the fixed contact. The moving contact 24 is supported by a switching arm 26 and can be moved or can be transferred between an open position, in which the fixed contact 22 and the moving contact 24 are at a distance from one another, and a closed position, in which the fixed contact 22 and the moving contact 24 are in electrically conductive physical contact, by using the switching arm.

[0066] Furthermore, the switching unit 4, 4 has a quenching device 28 for quenching a (switching) arc which is produced when the contacts 22, 24 are opened. The quenching device 28 has a quenching chamber 30 which is constructed as a deionization chamber with a stack of splitter plates 32, which are disposed parallel to one another, inserted therein. In the figures, the splitter plates 32 are provided with reference signs merely by way of example.

[0067] Furthermore, the quenching device 28 has a prechamber 34, through the use of which the arc is guided from the contacts 22, 24 to the quenching chamber 30. The prechamber 34 has a first arc guide rail 36 and a second arc guide rail 38. In this case, the arc guide rail 36 is constructed in an integral manner with a magnet yoke 40 of a short-circuit release 42 of a release mechanism 44 of the circuit breaker 2 (FIG. 4, FIG. 5). The arc guide rail 38 is formed together with a current supply 46 as an integrally coherent sheet-metal part, wherein the current supply 46 at the same time forms a support for a bimetallic strip 48 of an overload release 50 of the release mechanism 44 (FIG. 4, FIG. 5).

[0068] Furthermore, the prechamber 34 has two insulating side walls 52 as lateral covering plates between which the arc guide rails 36, 38 are enclosed. The side walls 52 and the arc guide rails 36, 38 therefore form an arc guide space for guiding the arc from the contacts 22, 24 to the quenching chamber 30.

[0069] As is clear from FIG. 2, in particular, ferromagnetic shaped parts 54 are attached to the outer surfaces, that is to say to the surfaces which face the end sides 20, of the side walls 52 of the switching unit 4. The shaped parts 54 have an outer contour which is matched approximately to the profile of the arc guide rails 36, 38. The shaped parts 54 are constructed as a composite part with a molded-on insulation 56 which is disposed on that end side of the shaped parts 54 which faces the quenching chamber 30.

[0070] In the alternative construction of the switching unit 4, two shaped magnets 54 are provided instead of the ferromagnetic shaped parts 54. The shaped magnets 54 have substantially the same shape or contour as the shaped parts 54. In particular, the shaped magnets 54 are likewise provided with the insulation 56. This means that the shaped magnets 54 and the shaped parts 54 differ substantially only in terms of the material used.

[0071] FIG. 3 shows the switching unit 4, 4 of FIG. 2 with a side wall 52 removed. As is clear from FIG. 3, a heat-resistant permanent magnet 58 is disposed in the region of the fixed contact 22. In this case, in the embodiment of the switching unit 4, the permanent magnet 58 can be provided in addition to the shaped magnets 54. An embodiment of the switching unit 4 without the permanent magnet 58 is likewise also conceivable for example.

[0072] Due to the use of the permanent magnet 58 in addition to the two shaped magnets 54, the resulting magnetic field is bundled particularly intensely in the region of the fixed contact 22, and therefore the arc is moved particularly rapidly from the fixed contact onto the arc guide rail 36. To this end, the shaped magnets 54like the shaped parts 54are each disposed on one of the side walls 52.

[0073] The permanent magnet 58 generates a magnetic field which guides the arc along the arc guide rail 36. To this end, the permanent magnet 58 is disposed radially on the inside of aas seen from the fixed contact 22convex bend or curvature 60 of the arc guide rail 36. Therefore, the permanent magnet 58 is disposed substantially within the profile of the arc guide rail 36.

[0074] The insulating side walls 52 insulate the ferromagnetic shaped parts 54 or the shaped magnets 54 in relation to the arc, and therefore the shaped parts 54 or the shaped magnets 54 are, in particular, not heated up beyond their respective Curie point, and therefore are changed to a paramagnetic state. The end sides of the side walls 52 project beyond the contact point of the contacts 22, 24, and therefore the contacts are enclosed substantially between the side walls 52 of the prechamber 34. Therefore, the arc is already pinched between the side walls 52 when it is produced, which results in an increase in voltage.

[0075] The shaped parts 54 of the switching unit 4 bundle the magnetic field of the permanent magnet 58. Due to the configuration of the permanent magnet 58 close to the fixed contact 22, the resulting magnetic force acts immediately on the arc produced and draws the arc down from the fixed contact 22 onto the arc guide rail 36. In other words, the arc, when it is produced by the magnetic field, is particularly rapidly commutated onto the arc guide rail 36 and guided to the quenching chamber 30.

[0076] Accordingly, the magnetic field is generated by the shaped magnets 54 of the switching unit 4 in addition or as an alternative to the magnetic field of the permanent magnet 58, and therefore commutates the arc from the fixed contact 22 onto the arc guide rail 36 due to the resulting magnetic force.

[0077] FIGS. 4 and 5 show a further embodiment of the switching unit 4, 4. In this exemplary embodiment, the moving contact 24 is constructed in one piece, that is to say in one part or monolithically, at the free end of the switching arm 26. FIGS. 4 and 5 show the prechamber 34 without the side walls 52 and therefore without the shaped parts 54 or shaped magnets 54 which, however, delimit the arc guide space of the prechamber 34 toward the end sides 20 in the assembled state in this embodiment too.

[0078] In addition to the switching unit 4, FIGS. 4 and 5 show the manual operating mechanism 14 and also the release mechanism 44 including the short-circuit release 42 and the overcurrent release 50. The manual operating mechanism 14 and the release mechanism 44 and also the switching arm 26 of the switching unit 4, 4 form a switching lock, not provided with a specific designation, of the circuit breaker 2.

[0079] The manual operating mechanism 14 is substantially formed by the pivot lever 12 and also a coupling rod 62 and a torsion spring 64.

[0080] In the exemplary embodiment shown, the switching arm 26 is constructed with two elements and has a contact lever 66, with the moving contact 24 at the free end, and a latching lever 68. The switching arm 26 is pretensioned by using a tension spring 70.

[0081] The release mechanism 44 includes a release slide 72 and the overload release 50, which is formed substantially from the bimetallic strip 48, and also the electromagnetic short-circuit release 42. The short-circuit release 42 includes a magnet coil 74 and a magnet core 76 and also the magnet yoke 40 and a magnet armature 78. In this case, the magnet armature 78 is coupled to a plastic rod, not specifically shown, which is held in a pretensioned manner by using a compression spring.

[0082] In the assembled state, the latching lever 68 of the switching arm 26 is mounted in such a way that it can pivot about a rotation shaft 80 which is fixed to the housing. The contact lever 66 is connected in an articulated manner to the latching lever 68 by using a rotary joint 82, and therefore the switching arm 26 inherently has a certain degree of flexibility. The resulting relative mobility of the contact lever 66 with respect to the latching lever 68 is limited by an elongate hole 84 at the rear end, that is to say the end which is averted from the moving contact 24, of the contact lever 66 into which the rotation shaft 80 engages in the manner of a linear guide.

[0083] The moving contact 24 interacts with the fixed contact 22 in order to switch an electrical circuit. In this case, the fixed contact 22 is attached, in particular on a top side of the magnet yoke 40, to the attachment of the arc guide rail 36 which is integrally connected to the magnet yoke.

[0084] FIG. 4 shows the switching unit 4, 4 in a closed state or in a closed position of the switching arm 26 in which the free end of the contact lever 66, which free end forms the moving contact 24, bears against the fixed contact 22. In this closed position, an electrically conductive connection is produced between a feed connection 86 or coupling contact 88 and a load connection 90 of the circuit breaker 2, which electrically conductive connection passes through a busbar 92, the magnet coil 74, the magnet yoke 40, the fixed contact 22, the contact lever 66 with the moving contact 24, the bimetallic strip 48 and an adjoining busbar 94. The electrical connection between the rear end of the contact lever 66 and the bimetallic strip 48 and also between the bimetallic strip 48 and the busbar 94 is closed by using a stranded connection 96, which is merely schematically illustrated in FIG. 4, in each case.

[0085] The core component of the release mechanism 44 is the release slide 72 which is operated both by the bimetallic strip 48 of the overload release 50 and also by the plastic rod of the short-circuit release 42, which plastic rod is coupled to the magnet armature 78, and resets the switching arm 26 from the closed position to the open position (FIG. 5) given operation of one of the releases 50 or 42.

[0086] A short circuit in an electrical circuit which is connected to the connections 86 and 90 leads to a sudden increase in the current flowing through the magnet coil 74. The sharp increase in current causes a proportional increase in the magnetic field which is generated by the magnet coil 74, as a result of which the magnet armature 78 is operated. Due to the resulting movement, the release slide 72 is operated and therefore the contacts 22 and 24 are separated.

[0087] In this case, FIG. 5 shows a final state of a release process in which the moving contact 24 bears against a stop surface 98 which forms an attachment of the second arc guide rail 38, which attachment is situated at a distance opposite the fixed contact 22.

[0088] During the course of a release process of this kind, the (switching) arc is produced between the fixed contact 22 and the moving contact 24 which lifts away from the fixed contact, the (switching) arc leading to intense heating and, in the long term, to erosion of the contacts 22 and 24. In this case, the quenching device 28 serves for rapid effective quenching of the arc.

[0089] When the contacts 22 and 24 are opened, the current flow within the contact lever 66, the arc section and the section of the magnet yoke 40 which is situated opposite the contact lever 66 acts as a current loop. This current loop, in addition to a Lorentz force due to the magnetic field of the permanent magnet 58 that is bundled by using the shaped parts 54, exerts an induction force on the arc, which induction force drives the arc in the direction of the quenching chamber 30.

[0090] When the switching arm 26 strikes the stop surface 98, the conductive connection between the bimetallic strip 48, the stranded connections 96 (FIG. 4) and the contact lever 66 is short-circuited through the current supply 46. The shaping of the metal strip from which the current supply 46 and the arc guide rail 38 are integrally formed ensures that the sign of the induction effect of the current flow on the arc is maintained during this process.

[0091] The arc guide rail 38 is cut out of the current supply 46 in such a way that the arc guide rail 38, in the region of the stop surface 98, is guided along the contact lever 66 which bears against it in its open position, and enters the current supply 46 only after the moving contact 24as seen along the contact lever 66 from the moving contact 24. The current which is guided from the fixed contact 22 through the arc section to the moving contact 24 therefore has to flow a certain distance in the direction of the elongate hole-side lever end, even if the contact lever 66 is already bearing against the stop surface 98, within the contact lever 66 or the arc guide rail 38, in the same way as before the contact lever 66 strikes, until it is diverted in the opposite direction through the current supply 46. In this case, the arc guide rail 38 is cut, in particular centrally, out of the current supply 46 in order to ensure as symmetrical a current flow as possible in the transition region.

[0092] With regard to the electrodynamic interaction of the current path, the magnet yoke 40 in which the guide rail 36 is integrated is not closed in a circular manner around the magnet coil 74 either. Instead, the magnetic yoke 40 is interrupted on a bottom side, which faces the magnet armature 78, by a narrow air gap 100 (FIG. 4). In this case, the air gap 100 is dimensioned in such a way that it does not significantly adversely affect the magnetic flow within the magnet yoke 74 but effectively suppresses a current flow through the gap section. Instead, a current path which is directed in the direction of the fixed contact 22 and the arc guide rail 36 is constantly forced within the magnet yoke 40. In the context of the present description, the direction of the current path is specified independently of the actual direction of current flow as starting from the feed connection 86 or coupling contact 88 and oriented toward the load connection 90.

[0093] Overall, the geometric characteristics of the current flow within the circuit breaker 2 and the resulting induction effect are retained over the entire release process until the arc is extinguished.

[0094] Under the induction effect and also in particular due to the bundled magnetic field of the permanent magnet 58, the arc becomes detached from the contacts 22 and 24 at the latest after the contact lever 66 strikes the stop surface 98, and moves to the adjoining arc guide rails 26 and 38. This process is referred to as commutation. The arc then migrates, in a manner enclosed by the side walls 52 and shaped parts 54 or the shaped magnets 54, furthermore under the influence of the electrodynamic forces, along the arc guide rails 36 and 38 in the arc guide space, which is formed between them, of the prechamber 34 to an inlet 102 of the quenching chamber 30.

[0095] The arc enters the quenching chamber 30 through the inlet 102 and is split into a number of partial arcs by the splitter plates 32. The splitter plates 32 promote quenching of the arc in a manner which is known per se by way of the total voltage which is dropped across the entire arc section being multiplied and the arc being cooled.

[0096] The invention is not restricted to the exemplary embodiments described above. Instead, other variants of the invention can also be derived therefrom by a person skilled in the art without departing from the subject matter of the invention. In particular, all of the individual features described in connection with the exemplary embodiment can furthermore also be combined with one another in a different way without departing from the subject matter of the invention.

[0097] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0098] 2 Circuit breaker [0099] 4, 4 Switching unit [0100] 6 Switching housing [0101] 8 Front side [0102] 10 Central part [0103] 12 Pivot lever [0104] 14 Manual operating mechanism [0105] 16 Rear side [0106] 18 Latching groove [0107] 20 End side [0108] 22 Fixed contact [0109] 24 Moving contact [0110] 26 Switching arm [0111] 28 Quenching device [0112] 30 Quenching chamber [0113] 32 Splitter plate [0114] 34 Prechamber [0115] 36, 38 Arc guide rail [0116] 40 Magnet yoke [0117] 42 Short-circuit release [0118] 44 Release mechanism [0119] 46 Current supply [0120] 48 Bimetallic strip [0121] 50 Overload release [0122] 52 Side wall [0123] 54 Shaped part [0124] 54 Shaped magnet [0125] 56 Insulation [0126] 58 Permanent magnet [0127] 60 Curvature/bend [0128] 62 Coupling rod [0129] 64 Torsion spring [0130] 66 Contact lever [0131] 68 Latching lever [0132] 70 Tension spring [0133] 72 Release slide [0134] 74 Magnet coil [0135] 76 Magnet core [0136] 78 Magnet armature [0137] 80 Rotation shaft [0138] 82 Rotary joint [0139] 84 Elongate hole [0140] 86 Feed connection [0141] 88 Coupling contact [0142] 90 Load connection [0143] 92, 94 Busbar [0144] 96 Stranded connection [0145] 98 Stop surface [0146] 100 Air gap [0147] 102 Inlet