EP3766090B1 - Circuit breaker for isolating an electrical circuit - Google Patents

Description

The invention relates to a circuit breaker with a switching unit as a disconnecting device for interrupting a circuit, having a stationary fixed contact and a moving contact which can be moved relative to the fixed contact and can be transferred from a closed position to an open position, and a quenching device for extinguishing an arc that occurs when the contacts open , with an antechamber for guiding the arc from the contacts to an arcing chamber.

Reliable separation of electrical components or devices from a switching or electric circuit is desirable, for example, for installation, assembly or service purposes and in particular for general personal protection. A corresponding switching unit or isolating device must be able to carry out an interruption under load, ie without first switching off a voltage source feeding the circuit. Mechanical switches (switching contact) can be used to disconnect the load. These have the advantage that when the contact has been opened, the electrical device is electrically isolated from the voltage source.

Switching arcs often occur when the current-carrying electrical contacts are separated, particularly with direct voltages above 24 volts (DC) to be switched, in that the electrical current continues to flow along an arc path in the form of an arc discharge after the contacts have opened. Since such switching arcs may not extinguish automatically with direct voltages from about 50 volts and direct currents from about 1 ampere, for example So-called snap-action contacts are used as a mechanical contact system, in which mechanical springs are used to accelerate the contact separation.

The arcs that occur when the contacts open under load are quickly moved to the quenching devices provided for this purpose, where the corresponding arc quenching takes place. The force required for this is provided, for example, by magnetic fields, so-called blowout fields, which are typically generated by one or more permanent magnets. Due to the special design of the contact zones and the arc conducting piece, the arc is guided into the appropriate arcing chambers, where the arc is extinguished according to known principles.

Basic measures for avoiding or controlling such switching arcs essentially consist of using an insulating material to increase the dielectric strength and thus arc quenching even with a small contact gap or to reduce the arc voltage by dividing the arc.

From the DE 20 2006 021 064 U1 describes a circuit breaker with a switching unit in which a (switching) arc that occurs when a contact system is opened is extinguished by means of a quenching device. The quenching device has an antechamber with two arcing rails, which are arranged between two insulating side or cover walls as a lateral delimitation for arcing. The arc is guided to an arcing chamber by means of the antechamber and is extinguished there.

The invention is based on the object of specifying a particularly suitable circuit breaker for disconnecting a circuit.

The object is achieved with the features of claim 1 according to the invention. Advantageous refinements and developments are the subject of the dependent claims.

The circuit breaker according to the invention is suitable and set up for interrupting a circuit, in particular a DC circuit. The circuit breaker is therefore designed as a switching device for manually and/or automatically switching off electrical circuits or individual consumers when permissible current or voltage values (overcurrent, fault current) are exceeded.

For this purpose, the circuit breaker has a switching unit as a disconnecting device with a switchable mechanical contact system. Here and in the following, “switching” means in particular a mechanical or galvanic contact separation (“opening”) and/or a contact closure (“closing”) of the contact system.

The contact system has a stationary fixed contact and a moving contact. The moving contact can be moved relative to the fixed contact and can be transferred from a closed position to an open position. This means that in order to switch the contact system or the switching unit, the moving contact is moved between the open position and the closed position.

The switching unit also has a quenching device for quenching a (switching) arc that occurs when the contacts open. The quenching device is designed with a quenching chamber for quenching the switching arc and with a pre-chamber for guiding the arc from the contacts to the quenching chamber.

The antechamber has two insulating side walls as side cover plates, with a pair of arc runners sitting between the side walls. The antechamber is thus open on both sides at the ends, with one end facing the contact system and the other end facing the arcing chamber. The antechamber thus forms an arc running space, which is delimited towards the sides by means of the insulating side walls as cover plates and the arc running rails for guiding the arc. The transition of the arc from the contacts of the contact system to the adjacent ones Arc rails of the antechamber are also referred to below as commutation.

The quenching chamber suitably has an inlet, which faces the open front side of the pre-chamber, and an oppositely arranged outlet for the gas flow of the arc.

In a first embodiment of the invention, a ferromagnetic molded part is arranged according to the invention on the side walls, which is preferably adapted to the course of the arc rails. The molded parts are produced in a simple manner, for example as stamped parts. In this case, the molded parts are preferably applied outside of the arc running space, that is to say on the outside of the side walls of the antechamber. The molded parts essentially surround the entire surface of the arc running space of the antechamber.

In this version, a permanent magnet (permanent magnet) is also arranged in the area of the fixed contact, the magnetic field of which guides the arc along one of the arc guide rails. This enables an arc that is produced to be extinguished particularly quickly and effectively. A particularly effective and reliable switching unit is thus realized.

The ionized (switching) arc is forced or channeled in the direction of the arcing chamber due to the electrodynamic interactions with the magnetic field of the permanent magnet. On the one hand, the ferromagnetic molded parts as side plates allow the magnetic field to be bundled or focused in the immediate contact area of the contacts. On the other hand, the arc magnetic field, which accompanies the arc, tends to pass through the more magnetically conductive molded parts in the vicinity of a ferromagnetic material. This creates a "suction effect" towards the mold parts, which causes the arc to move to the antechamber.

The ferromagnetic molded parts are at least partially magnetized by the magnetic field of the permanent magnet, so that the magnetic field or whose magnetic field lines are effectively bundled between the arc rails, i.e. concentrated or focused. This concentrated bundling of the magnetic field results in a particularly even and rapid arcing right into the quenching packet.

The permanent magnet is suitably made of a refractory material. This means that the permanent magnet is made of a magnetic material that retains its magnetic properties even at high temperatures, such as those that occur in particular in the area of the arc. In other words, for example, a magnetized ferromagnetic material is used for the permanent magnet, the material-specific Curie temperature of which is greater than the temperatures to be expected in the area of the arc.

The permanent magnet is made, for example, from a samarium alloy, in particular a samarium-cobalt alloy, preferably Sm ₂ Co ₁₇ , or a neodymium alloy, in particular neodymium-NiCuN, or an aluminum alloy, in particular AlNiCo500. In this case, the permanent magnet generates a magnetic field with a magnetic field strength of between 900 mT (milli-Tesla) and 1500 mT, in particular between 1000 mT and 1250 mT.

As a result, the arc is commutated particularly quickly from the fixed contact to the running rails and is thus drawn away from the contact system. This reduces the contact material losses in the area of the contacts due to arcing. Furthermore, the arc is moved particularly stably and quickly on the arc guide rail due to the magnetic field concentrated by the molded parts.

In a preferred embodiment, the quenching device is optimized in such a way that a switching arc is “sucked in” quickly and effectively into the quenching chamber by means of the antechamber and the permanent magnet, without passing through the quenching chamber and igniting back at the outlet or bouncing off the quenching chamber and igniting back before its inlet. Through the fast and reliable A particularly effective quenching device is implemented by guiding the arc by means of the antechamber, so that the quenching chamber can be designed to be particularly flat with sufficiently good quenching behavior. This enables a switching unit that is particularly compact in terms of installation space.

In a conceivable embodiment, two shaped magnets are provided in addition to the permanent magnet to guide the arc. In this case, the permanent magnet is suitably arranged between the mold magnets. This ensures that the arc is guided to the arcing chamber in a particularly reliable and reliable manner.

The advantages and preferred configurations given with regard to the first embodiment described above can also be transferred to the alternative embodiment described below, and vice versa.

In an alternative embodiment which is not claimed, the switching unit has, in contrast to the embodiment described above, instead of the shaped parts, in particular a shaped magnet in each case, with the common magnetic field generated by the shaped magnets guiding the arc along one of the arc running rails.

In this case, the molded magnets essentially have the same geometric shape or contour as the ferromagnetic molded parts. It is thus conceivable, for example, to design the molded parts and the molded magnets to be interchangeable.

The circuit breakers according to the invention thus each have a particularly effective extinguishing device for extinguishing switching arcs that occur. Thanks to the improved quenching behavior of the quenching device of the circuit breakers, these can be designed to be particularly flat. This enables a flat circuit breaker design, which improves its use in installation situations with reduced installation space, such as in control cabinets.

According to the invention, the arc guide rail, along which the arc is guided by means of the magnetic field of the permanent magnet, if necessary the shaped magnet, is brought up to the fixed contact. In this case, the arcing rail has a curved or curved course from the fixed contact to the arcing chamber. As a result, a particularly expedient and reliable course of the arc guide rail is realized.

According to the invention, this (first) arcing rail connects the fixed contact to a first side wall of the arcing chamber. Starting from the fixed contact, the arcing rail has a convex profile due to the bend. Due to the curvature or bend, the arc is guided away from the fixed contact in a particularly reliable manner, so that material loss or wear of the fixed contact is reduced.

The other (second) arcing rail preferably connects a stop surface, on which the moving contact rests in the open position, to a second side wall of the arcing chamber, so that reliable commutation of the arc is also made possible in the area of the moving contact.

In a suitable development, the first side wall of the arcing chamber is in particular as a magnetic yoke of a short-circuit release of a release mechanism of the circuit breaker. The (first) arc running rail is in particular designed integrally with the magnet yoke.

According to the invention, the permanent magnet is arranged radially on the inside of the (first) arc running rail in relation to the bending radius of the bend or curvature. With such a radially inner arrangement of the permanent magnet, it is thus arranged outside the antechamber. In particular, the permanent magnet is thus at least partially surrounded or bordered by the (first) arc running rail. In the case of a convex course of the (first) arc running rail, this is guided around the permanent magnet in an approximately U-shape or V-shape. Thus, the permanent magnet is protected from direct contact with the arc in a reliable and structurally simple manner. This significantly improves the service life of the permanent magnet.

In an expedient embodiment, the ferromagnetic molded parts and/or the molded magnets each have electrical insulation on the end faces oriented towards the arcing chamber. In other words, the molded parts or molded magnets are provided with insulation towards the inlet of the arcing chamber. This prevents an electrical short circuit along the arcing chamber and the mold parts or mold magnets. As a result, this is advantageously transferred to the service life of the quenching device and thus of the switching unit.

In a preferred embodiment, the molded parts or molded magnets are injection molded as inserts with the insulation in the area of the end faces. In an alternative Embodiment, the molded parts or molded magnets are inserted on the front side in particular in an insulating part. In other words, the insulation is injection molded and/or encapsulated or inserted in process technology on the ferromagnetic molded parts or molded magnets. This means that the molded part or the molded magnet and the insulation are designed in particular as a composite part. This ensures a particularly simple and inexpensive production and insulation of the molded parts or molded magnets. A particularly cost-effective circuit breaker is thus realized.

An additional or further aspect of the invention provides that the quenching chamber is designed as a deion chamber with an arc quenching package, ie with a stack of quenching packages with a number of arc splitters or scattering plates. Ferromagnetic materials, for example, are used as the material for the arc splitters, since the magnetic field that accompanies the arc tends to pass through the better magnetically conducting arc splitters in the vicinity of a ferromagnetic material. This creates suction towards the splitters, causing the arc to travel to and split between the array of splitters.

In a preferred embodiment, the moving contact of the switching unit used is arranged on a pivotable switching arm, which is coupled to a manual operating mechanism for manually adjusting the switching arm between the open position and the closed position, and to a triggering mechanism for automatically returning the switching arm to the open position when a triggering condition occurs is. As a result, a particularly suitable circuit breaker is realized.

The manual operating mechanism has, for example, a pivoting lever which is coupled to the switching arm by means of a mechanism. The mechanism has, for example, a spring element, expediently a torsion spring, which prestresses the pivoting lever in the direction of a first pivoting position corresponding to the open position of the switching arm, so that the pivoting lever always automatically moves into this first pivoting position in the unloaded state returns. In contrast, in a second pivoted position corresponding to the closed position of the switching arm, the pivoted lever is preferably locked by latching of the mechanism with the switching arm located in the closed position. The switching arm and the manual operating device are expediently matched to one another in such a way that when the switching arm returns to the open position and the pivoted lever returns to the first pivoted position, the mechanism automatically latches to the switching arm, so that the switching arm can be immediately adjusted again using the manual operating mechanism without any further action.

The triggering mechanism preferably has a short-circuit release which is designed to actuate the triggering mechanism in the event of an electrical short circuit as a triggering condition. The short-circuit release has, for example, a magnet coil, a magnet yoke and a magnet armature, with the magnet yoke forming in particular a first side wall of the arcing chamber.

In addition or as an alternative to the short-circuit release, the release mechanism preferably has an overload release or overcurrent release. The overload release is essentially formed by a bimetallic strip, for example, which heats up as a result of the current flow and deforms in such a way that in the event of an overload, i.e. the associated triggering condition, it actuates the triggering mechanism and thus the switching arm or the contact system.

In a suitable development, the switching unit and the triggering mechanism as well as the manual operating mechanism are accommodated at least partially in a common switch housing. This provides reliable contact protection (finger protection).

The side walls of the switch unit are oriented parallel to the end faces of the switch housing, with a gap area, ie a clearance, being formed between the antechamber and the switch housing. Such a gap area is particularly advantageous for pressure equalization in the course of an arc extinguishing. In this case, the gap area is preferably on the end faces the antechamber, i.e. open to contacts and to the inlet. Due to the sudden heating of the air, the arc pushes a pressure wave in front of it in the antechamber, which can impede the entry of the arc into the arcing chamber. The gap area between the switching housing and the antechamber enables pressure equalization in front of and behind the antechamber, so that the arc is not prevented from entering the arcing chamber. This ensures that the arc is extinguished in a particularly safe and reliable manner.

Fig. 1

einen Schutzschalter,

Fig. 2

eine Schalteinheit des Schutzschalters mit einem Kontaktsystem und mit einer Löscheinheit, welche eine Vorkammer mit zwei Seitenwänden sowie eine Löschkammer aufweist,

Fig. 3

die Schalteinheit aus Fig. 2 mit einer abgenommenen Seitenwand,

Fig. 4

eine alternative Ausführungsform der Schalteinheit mit einem Handbetätigungsmechanismus und mit einem Auslösemechanismus des Schutzschalters, und

Fig. 5

in vergrößerter Detailansicht die Ausführungsform gemäß Fig. 4.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. It shows in perspective representations:

1

a circuit breaker,

2

a switching unit of the circuit breaker with a contact system and with an arcing unit, which has an antechamber with two side walls and an arcing chamber,

3

the switching unit off 2 with a removed side wall,

4

an alternative embodiment of the switching unit with a manual override mechanism and with a tripping mechanism of the circuit breaker, and

figure 5

in an enlarged detail view the embodiment according to FIG 4 .

Corresponding parts and sizes are always provided with the same reference symbols in all figures.

The 1 shows a circuit breaker 2 for interrupting a circuit. For this purpose, the circuit breaker 2 based on the Figures 2 to 5 Switching unit 4 explained in more detail. The circuit breaker 2 also has a switch housing 6 made of an insulating material.

The circuit breaker 2 is preferably designed in the manner of a series installation device. The switching housing 6 correspondingly has a shape that is characteristic of such devices and is stepped symmetrically to a front side 8 . at one protruding central part 10 of the front side 8 protrudes for the manual actuation of the switching unit 4 a swiveling lever 12 of a manual operating mechanism 14 ( 4 , figure 5 ) out of the switch housing 6. On a rear side 16 opposite the front side 8, the circuit breaker 2 is provided with a latching groove 18, which is typical for rail-mounted devices, for latching onto a mounting rail, in particular a top-hat rail. Two end faces 20 of the switch housing 6 are arranged perpendicularly to the front side 8 and the rear side 16, along which the circuit breaker 2 is lined up in the installed or assembled state of a rail-mounted device.

The figures 2 and 3 show a first and second embodiment of the switching unit 4, 4'. The switching unit 4, 4' has a mechanical contact system with a stationary fixed contact 22 and with a moving contact 24 that can be moved relative thereto. The moving contact 24 is carried by a switching arm 26 and can be moved by means of this between an open position in which the fixed contact 22 and the moving contact 24 are spaced apart from one another and a closed position in which the fixed contact 22 and the moving contact 24 are in electrically conductive physical contact or transferrable.

The switching unit 4, 4' also has a quenching device 28 for quenching a (switching) arc that occurs when the contacts 22, 24 open. The quenching device 28 has a quenching chamber 30 which is designed as a deion chamber with a set of quenching plates 32 arranged parallel to one another inserted therein. In the figures, the quenching plates 32 are provided with reference numbers only by way of example.

The quenching device 28 also has an antechamber 34, by means of which the arc is guided from the contacts 22, 24 to the quenching chamber 30. The antechamber 34 has a first arc runner 36 and a second arc runner 38 . The arcing rail 36 is in this case designed integrally with a magnetic yoke 40 of a short-circuit release 42 of a release mechanism 44 of the circuit breaker 2 ( 4 , figure 5 ). The arc runner 38 is formed together with a power supply 46 as a one-piece coherent sheet metal part, the power supply 46 simultaneously forming a carrier for a bimetallic strip 48 of an overload release 50 of the release mechanism 44 ( 4 , figure 5 ).

The antechamber 34 also has two insulating side walls 52 as lateral cover plates, between which the arc rails 36, 38 are enclosed. The side walls 52 and the arcing rails 36, 38 thus form an arcing space for guiding the arc from the contacts 22, 24 to the arcing chamber 30.

As in particular in the 2 As can be seen, ferromagnetic molded parts 54 are applied to the outer surfaces, ie to the surfaces facing the end faces 20, of the side walls 52 of the switching unit 4. The molded parts 54 have an outer contour which is approximately adapted to the course of the arc rails 36, 38. The molded parts 54 are designed as a composite part with an injection-moulded insulation 56 which is arranged on the end face of the molded parts 54 facing the arcing chamber 30 .

In the alternative embodiment of the switching unit 4', two molded magnets 54' are provided instead of the ferromagnetic molded parts 54. The mold magnets 54 ′ have essentially the same shape or contour as the mold parts 54 . In particular, the mold magnets 54' are also provided with the insulation 56. This means that the shaped magnets 54' and the shaped parts 54 differ essentially only in the material used.

The 3 shows the switching unit 4, 4 'of 2 with a removed side panel 52. As in the 3 As can be seen, a heat-resistant permanent magnet 58 is arranged in the area of the fixed contact 22 . The permanent magnet 58 is provided here in addition to the shaped magnets 54' in the embodiment of the switching unit 4'.

By using the permanent magnet 58 in addition to the two shaped magnets 54 ′, the resulting magnetic field is concentrated particularly strongly in the area of the fixed contact 22 , so that the arc is moved particularly quickly from the latter onto the arc guide rail 36 . For this purpose, the mold magnets 54 ′, like the mold parts 54 , are each arranged on one of the side walls 52 . The permanent magnet 58 generates a magnetic field which guides the arc along the arc guide rail 36 . For this purpose, the permanent magnet 58 is arranged radially on the inside of a convex bend or curvature 60 of the arc guide rail 36—seen from the stationary contact 22 . The permanent magnet 58 is thus arranged essentially within the course of the arc runner 36 .

The insulating side walls 52 insulate the ferromagnetic mold parts 54 or the mold magnets 54' from the arc, so that the mold parts 54 or the mold magnets 54' in particular are not heated above their respective Curie temperatures and are thus placed in a paramagnetic state. The side walls 52 protrude at the end beyond the contact point of the contacts 22, 24, so that these are essentially enclosed between the side walls 52 of the antechamber 34. The arc is thus "squeezed" between the side walls 52 as soon as it occurs, as a result of which an increase in voltage is brought about.

The molded parts 54 of the switching unit 4 bundle the magnetic field of the permanent magnet 58. Due to the arrangement of the permanent magnet 58 close to the fixed contact 22, the resulting magnetic force acts immediately on the arc that is created and pulls it down from the fixed contact 22 to the arc guide rail 36. In other words, when the arc is generated by the magnetic field, it is commutated particularly quickly onto the arc runner 36 and guided to the quenching chamber 30 .

Correspondingly, the magnetic field is generated by the shaped magnets 54' of the switching unit 4' in addition to the magnetic field of the permanent magnet 58, and thus the arc is commutated by the resulting magnetic force from the fixed contact 22 to the arc runner 36 .

The figures 4 and 5 show another embodiment of the switching unit 4, 4 '. In this exemplary embodiment, the moving contact 24 is designed in one piece, that is to say in one piece or monolithically, on the free end of the switching arm 26 . The figures 4 and 5 show the antechamber 34 without the side walls 52 and thus without the molded parts 54 or molded magnets 54′, which, however, in the assembled state also delimit the arc running space of the antechamber 34 towards the end faces 20 in this embodiment.

The figures 4 and 5 show, in addition to the switching unit 4, the manual operating mechanism 14 and the tripping mechanism 44 with the short-circuit release 42 and the overcurrent release 50. The manual operating mechanism 14 and the tripping mechanism 44 as well as the switching arm 26 of the switching unit 4, 4' form an unspecified switching mechanism of the circuit breaker 2.

The manual operating mechanism 14 is essentially formed by the pivoted lever 12 as well as a coupling rod 62 and a torsion spring 64.

In the exemplary embodiment shown, the switching arm 26 is designed in two parts and has a contact lever 66 with the movement contact 24 on the free end, and a ratchet lever 68 . The switching arm 26 is preloaded by means of a tension spring 70 .

The release mechanism 44 has a release slide 72 and the overload release 50 essentially formed from the bimetallic strip 48 and the electromagnetic short-circuit release 42 . The short-circuit release 42 has a magnet coil 74 and a magnet core 76 as well as the magnet yoke 40 and a magnet armature 78 . The magnet armature 78 is in this case coupled to a plastic rod, not shown in any more detail, which is kept prestressed by means of a compression spring.

In the assembled state, the pawl lever 68 of the switching arm 26 is pivotably mounted about an axis of rotation 80 fixed to the housing. The contact lever 66 is articulated on the pawl lever 68 by means of a rotary joint 82, so that the switching arm 26 has a certain degree of flexibility. The resulting relative mobility of the contact lever 66 with respect to the latch lever 68 is limited by a slot 84 at the rear end of the contact lever 66, ie the end facing away from the moving contact 24, in which the rotary axis 80 engages in the manner of a linear guide.

The moving contact 24 cooperates with the fixed contact 22 to switch a circuit. The fixed contact 22 is applied here in particular to an upper side of the magnet yoke 40 at the base of the arc guide rail 36 integrally connected thereto.

The 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 forming the moving contact 24 rests against the fixed contact 22. In this closed position, an electrically conductive connection is created between a feed connection 86 or coupling contact 88 and a load connection 90 of the circuit breaker 2, which is connected via 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 leads. The electrical connection between the rear end of the contact lever 66 and the bimetallic strip 48 and between the bimetallic strip 48 and the busbars 94 is closed in each case by means of a stranded connection 96, which in the 4 are shown only schematically.

The core component of the tripping mechanism 44 is the tripping slide 72, which is actuated both by the bimetallic strip 48 of the overload release 50 and by the plastic rod of the short-circuit release 42 coupled to the magnet armature 78, and which, when one of the releases 50 or 42 is actuated, resets the switching arm 26 from the closed position to the open position ( figure 5 ) causes.

A short circuit in a circuit connected to terminals 86 and 90 results in a sudden increase in the current flowing through solenoid coil 74 . The strong increase in current causes a proportional increase in the magnetic field generated by the magnet coil 74, as a result of which the magnet armature 78 is actuated. The resulting movement actuates the release slide 72 and thus the contacts 22 and 24 are separated.

The figure 5 shows an end state of a triggering process in which the moving contact 24 bears against a stop surface 98 which forms a projection of the second arcing rail 38 which is opposite the fixed contact 22 at a distance.

In the course of such a triggering process, the (switching) arc occurs between the fixed contact 22 and the moving contact 24 that lifts off from it, which leads to strong heating and, in the long term, to a burning of the contacts 22 and 24 . The quenching device 28 is used here to quickly and effectively extinguish the arc.

When the contacts 22 and 24 open, the current flow within the contact lever 66, the arc gap and the gap of the magnetic yoke 40 opposite the contact lever 66 acts as a current loop. In addition to a Lorenz force, this current loop exerts an inductive force on the arc due to the magnetic field of the permanent magnet 58 concentrated by means of the molded parts 54 , which force drives the arc in the direction of the arcing chamber 30 .

When the switch arm 26 hits the stop surface 98, the conductive connection between the bimetallic strip 48, the stranded wire connections 96 ( 4 ) and the contact lever 66 short-circuited via the power supply 46. The shape of the sheet metal strip from which the power supply 46 and the arc running rail 38 are integrally formed ensures that the inductive effect of the current flow on the arc is retained in terms of sign during this process.

The arcing rail 38 is released from the power supply line 46 in such a way that the arcing rail 38 is guided in the area of the stop surface 98 along the contact lever 66 which rests against it in its open position, and - viewed from the moving contact 24 along the contact lever 66 - only behind the moving contact 24 goes into the power supply 46. The current conducted from the fixed contact 22 via the arc gap to the moving contact 24 must therefore travel a certain distance in the direction of the slot-side, as before the contact lever 66 struck within the contact lever 66 or the arcing rail 38, even if the contact lever 66 is already in contact with the stop surface 98 Lever end flow until it is derived via the power supply 46 in the opposite direction. The arc guide rail 38 is cut out of the power supply line 46 in particular in the center in order to ensure the most symmetrical current flow possible in the transition area.

With regard to the electrodynamic interaction of the current path, the magnetic yoke 40, in which the running rail 36 is integrated, is also not closed in a circular manner around the magnetic coil 74. Rather, the magnet yoke 40 is on an underside facing the magnet armature 78 through a narrow air gap 100 ( 4 ) interrupted. In this case, the air gap 100 is dimensioned in such a way that it does not significantly impair the magnetic flux within the magnetic yoke 74, but effectively prevents a current flow across the gap distance. Instead, a current path directed in the direction of the fixed contact 22 and the arc guide rail 36 is always enforced within the magnet yoke 40 . Within the scope of this description, the direction of the current path is specified as starting from the feed connection 86 or coupling contact 88 and aligned with the load connection 90, independently of the actual direction of current flow.

Overall, the geometric characteristics of the current flow within the circuit breaker 2 and the induction effect caused thereby remain intact over the entire tripping process until the arc is extinguished.

Under the induction effect and in particular due to the concentrated magnetic field of the permanent magnet 58, the arc is released from the contacts 22 and 24 at the latest after the contact lever 66 has struck the stop surface 98 and is transferred to the adjacent arcing rails 26 and 38. This process is called commutation. The arc then migrates, enclosed by the side walls 52 and mold parts 54 or the mold magnets 54', still under the influence of the electrodynamic forces, along the arc runners 36 and 38 in the arc runner space of the antechamber 34 formed between them towards an inlet 102 of the arcing chamber 30 .

The arc enters the arcing chamber 30 via the inlet 102 and is divided into a number of partial arcs by the arc splitters 32 . The quenching plates 32 promote the quenching of the arc in a manner known per se, in that the total voltage dropping over the entire arc gap is multiplied and the arc is cooled.

The invention is not limited to the exemplary embodiments described above. On the contrary, other variants of the invention can also be derived from this by a person skilled in the art without departing from the subject matter of the invention.

Reference List

2

circuit breaker

4, 4'

switching unit

6

switch housing

8th

front

10

center part

12

swing lever

14

manual override mechanism

16

back

18

locking groove

20

face

22

fixed contact

24

moving contact

26

shift arm

28

extinguishing device

30

arcing chamber

32

quenching plate

34

antechamber

36, 38

arc runner

40

magnetic yoke

42

short-circuit release

44

release mechanism

46

power supply

48

bimetallic strips

50

overload release

52

Side wall

54

molding

54'

shape magnet

56

insulation

58

permanent magnet

60

curvature/bending

62

connecting rod

64

torsion spring

66

contact lever

68

latch lever

70

tension spring

72

trigger slide

74

magnetic coil

76

magnetic core

78

magnet anchor

80

axis of rotation

82

swivel joint

84

Long hole

86

feed connection

88

coupling contact

90

load connection

92, 94

power rail

96

stranded connection

98

stop surface

100

air gap

102

inlet

Claims (7)

1. Circuit breaker (2) with a switching unit (4, 4') for interrupting an electric circuit, said switching unit (4, 4') comprising

   - a stationary fixed contact (22) and a moving contact (24), which is movable relative to the fixed contact (22) and can be transferred from a closed position to an open position, and

   - a quenching device (28) for quenching an arc formed when the contacts (22, 24) are opened, said quenching device (28) comprising a prechamber (34) for guiding the arc from the contacts (22, 24) to an quenching chamber (30), said prechamber (34) having two insulating side walls (52) and a pair of arc guide rails (36, 38) disposed between said side walls (52),

   - wherein one of the arc guide rails (36), is guided to the fixed contact (22),

   - wherein said arc guide rail (36) has a curved or bent profile from the fixed contact (22) toward the quenching chamber (30), and

   - wherein the arc guide rail (36) connects the fixed contact (22) to a first side wall (40) of the quenching chamber (30), and has a convex profile starting from the fixed contact (22),

   characterized in

   - that a ferromagnetic shaped part (54) is arranged on each of the side walls (52) or that a shaped magnet (54') is arranged on each of the side walls (52), the common magnetic field of which guides the arc along the arc guide rail (36),

   - that a permanent magnet (58) is arranged in the area of the fixed contact (22), the magnetic field of which guides the arc along the arc guide rail (36),

   - that the permanent magnet (58) is arranged radially on the inside of the bend or curvature (60) of the arc guide rail (36), and

   - that the resulting magnetic field of the permanent magnet (58) and the shaped parts (54) or shaped magnets (54') is bundled in the region of the fixed contact (22).
2. Circuit breaker (2) according to claim 1,
   characterized in
   that the side wall (40) is formed by a magnetic yoke of a short-circuit release (42).
3. Circuit breaker (2) according to claim 1 or 2,
   characterized in
   that the ferromagnetic shaped parts (54) or the shaped magnets (54') each have an electrical insulation (56) on the end faces oriented toward the quenching chamber (30).
4. Circuit breaker (2) according to claim 3,
   characterized in
   that the shaped parts (54) or the shaped magnets (54') are overmolded as insert parts with the insulation (56) in the region of the end faces.
5. Circuit breaker (2) according to one of claims 1 to 4,
   characterized in
   that the quenching chamber (30) is designed as a deion chamber with an arc splitter stack.
6. Circuit breaker (2) according to one of claims 1 to 5,
   characterized in
   that the moving contact (24) of the switching unit (4, 4') is arranged on a pivotable switching arm (26), which is coupled to a manual operating mechanism (14) for manual adjustment of the switching arm (26) between the open position and the closed position, and to a release mechanism (44) for automatic return of the switching arm (26) to the open position when a release condition occurs.
7. Circuit breaker (2) according to claim 6,
   characterized in
   that the switching unit (4, 4') and the release mechanism (44) as well as the manual operating mechanism (14) are at least partially accommodated in a common switching housing (6).

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