EP3797438B1 - Disconnecting device for interrupting a direct current of a current path, and circuit breaker - Google Patents

Description

The invention relates to a disconnecting device for direct current interruption of a current path, in particular for a circuit breaker, comprising a hybrid switch which has a current-carrying mechanical contact system and a semiconductor switching system connected in parallel thereto. The invention further relates to a circuit breaker with such a disconnecting device.

A reliable separation of electrical components or devices from a switching or electrical circuit is desirable, for example, for installation, assembly or service purposes and in particular for general personal protection. A corresponding switching unit or disconnecting device must therefore be able to carry out an interruption under load, i.e. without first switching off a voltage source supplying the circuit.

Powerful semiconductor switches can be used to isolate the load. However, these have the disadvantage that unavoidable power losses occur on the semiconductor switches even during normal operation. Furthermore, with such power semiconductors it is typically not possible to ensure galvanic isolation and thus reliable personal protection. If, on the other hand, mechanical switches (switching contacts) are used to disconnect the load, a galvanic isolation of the electrical device from the voltage source is also achieved when the contact is opened.

The electrical contacts of such a mechanical switch or contact system are often as a stationary fixed contact and as a relative to it movable moving contact executed. The moving contact can be moved relative to the fixed contact and can be moved 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 by means of a switching movement.

In the closed position, the contacts of the contact system typically form a very small contact point at which the current flow through the contact system is concentrated. During operation, magnetic effects occur, in particular the so-called "Holm's narrow force", which exert a force on the contacts that loosens the contact between the moving and fixed contacts. In order to avoid this, such a contact system usually has a spring element which presses the moving contact against the fixed contact with a spring force, i.e. applies an additional contact force or contact pressure directed along the closed position.

However, in the event of a fault or overload current, it can happen that the Holm tightness force exceeds the contact force, causing the contacts to lift undesirably. Particularly when DC voltages above 24 volts (DC) are to be switched, switching arcs often occur when the current-carrying electrical contacts are disconnected, in that the electrical current continues to flow along an arc path in the form of an arc discharge after the contacts have been opened. Since such switching arcs may not extinguish automatically with direct voltages of around 50 volts and direct currents of around 1 ampere, the contact system can be damaged or completely destroyed.

So-called hybrid isolating devices are conceivable, which have a hybrid switch. Such a hybrid switch usually has a mechanical contact system and a semiconductor switching system connected in parallel. The semiconductor switching system has at least one power semiconductor switch, which is open when the contact system is closed, i.e is electrically non-conductive, and which is at least temporarily switched to conduct current when the contact system is opened.

In particular, when switching on, the semiconductor switching system is first activated and after a short delay, when the current flow has stabilized, the contact system is closed. The semiconductor switching system is then deactivated and the mechanical contact system takes over all of the current. Switching off occurs in the reverse order. As a result, the electrical current of the arc is conducted or commutated from the contacts of the contact system to the semiconductor switching system, whereby the arc between the switching contacts of the contact system is extinguished or does not arise from the start.

With such a hybrid disconnecting device, it is therefore possible to reliably prevent the switching arc between the contacts at least in a limited current range during a switching process in which the moving contact is moved into the open position, i.e. the mechanical contact system is opened. Suitably, the disconnecting device has a fuse which is arranged in series with the hybrid switch. The fuse ensures reliable protection of the system at currents above this current range.

When using such a disconnecting device in a circuit breaker, it must be ensured that the hybrid switch safely carries the fault or overcurrent, otherwise a reliable response of the (fusible) fuse within a specified characteristic curve is not guaranteed. In order to ensure that the fuse responds within the characteristic curve, even taking aging effects into account, an overcurrent of up to a few kiloamperes (kA) must be reliably carried by the mechanical contact system. It is therefore necessary to increase the contact pressure to a multiple of what would be necessary for low-resistance contacting of the contact system in a nominal current range.

In order to ensure a reliable response of the fuse, it is possible, for example, that one or more spring elements for generating the contact pressure are designed to be correspondingly oversized, so that the contact force or the contact pressure has a sufficient reserve for the tight force that occurs, for example with regard to mechanical vibrations . However, this disadvantageously increases both the manufacturing costs and the required installation space for the separating device. Furthermore, comparatively high power is required to switch and hold the contact system.

Particularly in contact systems with only one fixed contact and one moving constant, it is conceivable that the moving contact is designed as a (conductor) loop. During operation, the current flowing through the loop creates a magnetic field, which creates a magnetic force to support the contact force. This makes it possible to compensate for the tightness. The effect is independent of the direction of current flow.

It is also conceivable, for example, to align a magnetic field of a permanent magnet directly or by means of guide plates in the area of the contact system in such a way that, in cooperation with a magnetic field surrounding the moving contact in the course of the current flow, an advantageous effect on the contact pressure results. The direction of the magnetic force caused depends on the direction of current flow.

From the WO 2017/005450 A1 a disconnecting device for direct current interruption between a direct current source and an electrical device is known. The disconnecting device comprises a mechanical switch that has a first fixed contact, a second fixed contact and a contact bridge that is movable between a first position and a second position. In the first position, the first fixed contact and the second fixed contact are electrically contacted by means of the contact bridge, and in the second position the contact bridge is spaced apart from the first fixed contact and the second fixed contact. The contact bridge and the first fixed contact are electrically contacted with a semiconductor switch, which blocks current when the contact bridge is in the first position is. A control input of the semiconductor switch is connected to the mechanical switch in such a way that when the contact bridge moves into the second position, an arc voltage generated as a result of an arc across the switch switches the semiconductor switch to conduct current.

From the FR 2 570 869 A1 A separating device with two fixed contacts and two moving contacts arranged on a linearly movable contact bridge is disclosed. A magnetic element is arranged on the contact bridge, which is magnetized when a current flows through the contact bridge and interacts with the magnetic field of a stationary (second) magnetic element.

The invention is based on the object of specifying a particularly suitable disconnecting device for direct current interruption of a current path. The invention is also based on the object of providing a circuit breaker with a corresponding disconnecting device.

The disconnecting device according to the invention is suitable and set up for direct current interruption of a current path, in particular for a circuit breaker connected to the current path. The particularly hybrid disconnecting device has a hybrid switch for direct current interruption of the current path.

The hybrid switch has a switchable mechanical contact system. A “mechanical contact system” is to be understood below as meaning both a purely mechanical and an electromechanical contact system.

Here and below, “switching” is understood to mean in particular a mechanical or galvanic contact separation (“opening”) and/or a contact closing (“closing”) of the contact system. A semiconductor switching system of the hybrid switch is connected in parallel to the contact plug of the contact system. In other words, the hybrid switch has a parallel connection of the contact system and the semiconductor switching system. The semiconductor switching system expediently has at least one controllable power semiconductor switch.

The contact system has at least one stationary fixed contact and at least one moving contact that is relatively movable relative to this. The moving contact is carried by a current-carrying contact bridge (switching arm). The contact bridge is made, for example, from a copper material. The contact bridge is coupled to a drive system which moves the contact bridge - and thus the moving contact - from an open position into a closed position applied to the fixed contact with a contact force. In other words, the moving contact is subjected to a contact or contact pressure by means of the drive system, which ensures secure contact of the contacts. The drive system is preferably designed with a spring element, with the contact force (closing force) being effected as a preload or as a restoring force of the spring element.

According to the invention, at least one first magnetic element is arranged on the contact bridge, which is arranged at a distance from a stationary second magnetic element by means of an air gap in such a way that when a current flows through the contact bridge, a magnetic field is caused in the first magnetic element and a magnetic attraction of the first and second magnetic elements takes place . In other words, the first magnetic element guides the magnetic field generated by the current-carrying contact bridge, with the magnetic circuit being closed via the air gap by the second magnetic element. In the course of this attraction or magnetic interaction, a magnetic force (tensile force) that is the same as the contact force is caused, whereby the effective contact force of the moving contact on the fixed contact is increased.

In addition to the contact force of the drive system, the current flow causes a force effect between the two magnetic elements, which increases the contact pressure and thus counteracts any Holm tight force that occurs. In other words, the contact force and the magnetic force are directed opposite to the tightness force. The force effect is independent of the direction of current flow and therefore always reinforces the contact force.

Both the constriction force and the magnetic force caused increase in proportion to the square of the current flowing through the contact system. This means that in the event of an overcurrent or fault current, both the constriction force and the magnetic force increase in the same way, so that the magnetic force through the magnetic elements is always sufficiently dimensioned to compensate for the constriction force. This ensures that the contacts are always reliable and operationally safe. In particular, unwanted lifting of the contacts is counteracted advantageously and easily, even in the event of a fault or overcurrent. This creates a particularly suitable disconnecting device for direct current interruption of a current path.

In particular, the additional magnetic force for the contact pressure is only generated when it is needed to reliably press the moving contact onto the fixed contact. In contrast to the prior art, it is therefore not necessary to provide a higher dimensioned contact compression spring for the drive system, which reduces the manufacturing costs and the space required for the separating device. Furthermore, comparatively low attraction and holding energies or power are required when switching the contact system or the hybrid switch. Due to the reduced holding energy, the heat generated by the drive system is reduced, which means that a particularly compact drive system can be used. Furthermore, higher nominal currents can therefore be achieved. In the case of a design as a bistable contact system, it is therefore possible, for example, to use comparatively weak permanent magnets.

Since the mechanical contact system is part of a hybrid switch, no (switching) arc occurs when switching, especially when the contacts are opened. As a result, effects due to contact erosion can essentially be neglected, which means that the coordination of the magnetic elements can be set or specified particularly effectively through the air gap. In particular, the separating device therefore has essentially no change over its service life, at least with regard to the force effect of the magnetic elements.

The stationary second magnetic element is preferably not part of the hybrid switch, in particular not part of the movable contact system. The second magnetic element is arranged, for example, on a housing of the isolating device or the circuit breaker, so that the point of application of the magnetic force caused is arranged outside or at a distance from the drive system of the contact system. This means that the function of the magnetic elements is always guaranteed.

The air gap, for example, has a clear width of approximately 0.3 mm (millimeter) to 1 mm. The air gap preferably has a clear width of approximately 0.5 mm.

According to the invention, the current-carrying contact bridge itself is used to generate a magnetic field that supports the drive system. The magnetic elements thus act as an additional electromagnetic actuator or lifting magnet, the magnetic force of which acts directly on the contact bridge, so that the repulsion of the contacts that occurs at higher current strengths, especially in the kiloampere range (kA), is compensated for reliably and reliably. In particular, the contact system of the separating device according to the invention does not require any additional permanent magnets to generate the supporting tensile or closing force (magnetic force), which means that the separating device is particularly cost-effective. Furthermore, the function is independent of the direction of current flow, so that the contact system and thus the isolating device can be used essentially bidirectionally.

In contrast to the prior art, the tensile effect of the magnetic elements according to the invention enables optimized current conduction by means of the contact bridge compared to the repulsion of a loop-shaped contact bridge (conductor loop). This enables a very compact design of the separating device. Furthermore, a maximum effect is achieved when the contacts are closed. On the other hand, in the case of larger strokes of the contact (increased separation distance, higher voltages), a conductor loop would have to be made correspondingly wide and therefore ineffective. The contact bridge itself is therefore special Can be designed to be compact and material-saving, which further reduces power losses in the contact system.

In a suitable development, the mechanical contact system has two fixed contacts and two moving contacts. Suitably, the moving contacts are moved essentially simultaneously, i.e. synchronously, so that switching takes place at both switching or contact points essentially at the same time. In other words, the contact system - and thus the hybrid switch - has two pairs of contacts or separation points that are preferably spaced apart from one another. This makes particularly reliable switching of the contact system possible, which improves the switching behavior of the isolating device.

In an advantageous embodiment, the first magnetic element and the second magnetic element are each made from a soft magnetic material, in particular from a soft magnetic iron material. A soft magnetic material or material is to be understood here as meaning, in particular, a ferromagnetic material which is easily magnetized in the presence of a magnetic field. This magnetic polarization is generated in particular by the electrical current in the contact bridge through which current flows. The polarization increases the magnetic flux density in the respective magnetic element many times over. This means that a soft magnetic material “strengthens” an external magnetic field by its respective material permeability. This ensures that the highest possible magnetic force is generated between the magnetic elements, so that the narrow force is always reliably compensated.

Soft magnetic materials have a coercivity of less than 1000 A/m (amperes per meter). For example, a magnetic soft iron (RFe80 - Rfe120) with a coercive field strength of 80 to 120 A/m is used as a soft magnetic material. It is also conceivable, for example, to use a cold strip, such as EN10139-DC01+LC-MA ("transformer sheet"), which results in a particularly cost-effective design.

In an embodiment not according to the invention, the first magnetic element and the second magnetic element are designed as a paired yoke-anchor pair. One of the magnetic elements is designed as an approximately U-shaped or horseshoe-shaped magnetic yoke, with the other magnetic element suitably designed as a flat anchor plate.

In an embodiment not according to the invention, the contact bridge is approximately rectangular, with two moving contacts being provided, which are arranged on the opposite end faces of the contact bridge. This results in a particularly simple structure of the movable parts of the contact system. The moving contacts are preferably arranged on a common flat surface of the contact bridge, with the coupling to the drive system suitably taking place on the flat surface of the contact bridge opposite the moving contacts.

In a design not according to the invention, the first magnetic element is designed as a U-shaped magnetic yoke, which rests on the contact bridge in the area of the horizontal U-leg. The first magnetic element or magnetic yoke rests against the drive system with the horizontal U-leg, in particular in the area of the mechanical coupling, with the magnetic yoke encompassing the contact bridge at least in sections by means of the vertical U-leg.

Suitably, the vertical U-legs surround the contact bridge in such a way that the vertical U-legs of the first magnetic element of the contact bridge protrude in the direction of the fixed contacts and are arranged at a distance from a second magnetic element designed as an anchor plate by means of an air gap on the free end. The second magnetic element or the anchor plate is oriented essentially transversely to the contact bridge, i.e. approximately parallel to the horizontal U-leg of the first magnetic element or magnetic yoke.

In a development not according to the invention, the switching movement of the contact bridge, i.e. by means of the drive system and/or the magnetic elements caused movement of the contact bridge, linear. The conjunction “and/or” is to be understood here and below in such a way that the features linked by this conjunction can be formed both together and as alternatives to one another. This enables a particularly simple design and arrangement of the drive system and the contact bridge as well as the magnetic elements.

According to the invention, the contact bridge is essentially U-shaped, with two moving contacts being arranged at each free end of a respective vertical U-leg. The alternative design of the contact bridge can be produced inexpensively and enables particularly large separation distances between the contacts, i.e. large clear widths between the contacts in the open position. In this embodiment, the drive system is preferably designed as a hinged armature magnet system, whereby a particularly cost-effective, space-compact and long-lasting separating device is realized.

In an additional or further aspect of this embodiment, a first magnetic element designed as an anchor plate is arranged along the vertical U-legs of the contact bridge. Furthermore, two second magnetic elements designed as a U-shaped or horseshoe-shaped magnetic yoke are provided, which are arranged in the area of the fixed contacts, and which each have two vertical U-legs, which at least partially surround the oppositely arranged vertical U-leg of the contact bridge. This ensures a particularly uniform generation or effect of the supporting magnetic force in the area of the moving contacts.

According to the invention, the switching movement of the contact bridge takes place by means of a pivoting or rotary movement. The pivot or rotation axis is oriented in particular along or parallel to the horizontal U-leg of the contact bridge. Preferably, the contact bridge is attached or held on an approximately U-shaped spring element of the drive system, which is made, for example, as a stamped part from spring steel. The pivoting or rotating movement is realized in particular by a hinged armature magnet system, whereby the contact pressure is caused by the bending elasticity of the spring element. Particularly large isolating distances between the contacts can be created or implemented in a simple manner by means of the pivoting or rotary movement, whereby a particularly safe and reliable galvanic isolation of the isolating device is achieved.

Furthermore, the design with a U-shaped spring element, the vertical U-legs of which are arranged essentially aligned with those of the contact bridge, is particularly advantageous in that the contact system is reliably held in the closed position even in the event of external vibrations or shocks. In particular, with such rotary contact systems it is possible to position the center of mass of the moving contact bridge near the pivot point or the axis of rotation.

In a preferred application, the disconnecting device described above is part of a circuit breaker. The circuit breaker is expediently connected to a circuit between a direct current source and a consumer or a load, so that when the circuit breaker is actuated, the isolating device electrically isolates the consumer or the load from the direct current source.

The circuit breaker is designed in particular as a hybrid circuit breaker or as a hybrid (power) relay or as a circuit breaker device with a downstream fuse, and has a feed connection via which a mains-side and thus current-carrying power line is connected, as well as a load connection which the power line going out on the load side can be connected.

The circuit breaker is preferably suitable and set up for switching high voltages and direct currents, for example in the range of 6 kA. For this purpose, the separating device is expediently dimensioned accordingly in order to carry such high current intensities and to switch them safely. Through the inventive The disconnecting device ensures safe and reliable switching of the circuit breaker, even in the event of high overcurrents or fault currents.

Fig. 1

in schematischer Darstellung einen Stromkreis mit einer Gleichstromquelle und mit einem Verbraucher sowie mit einem dazwischen geschalteten Schutzschalter,

Fig. 2

in perspektivischer Darstellung ein mechanisches Kontaktsystem des Schutzschalters in einer nicht-erfindungsgemäßen Ausführungsform,

Fig. 3

in Schnittdarstellung das nicht-erfindungsgemäße Kontaktsystem,

Fig. 4

in perspektivischer Darstellung das nicht-erfindungsgemäße Kontaktsystem,

Fig. 5

in Seitendarstellung das nicht-erfindungsgemäße Kontaktsystem,

Fig. 6

in Draufsicht mit Blick auf eine Unterseite das nicht-erfindungsgemäße Kontaktsystem,

Fig. 7

in perspektivischer Darstellung eine erfindungsgemäße Ausführungsform des Kontaktsystems in einer Schließstellung,

Fig. 8

in perspektivischer Darstellung die alternative Ausführungsform des erfindungsgemäßen Kontaktsystems in einer Offenstellung,

Fig. 9

in Seitendarstellung ausschnittsweise das erfindungsgemäße Kontaktsystem in der alternativen Ausführungsform,

Fig. 10

in Schnittdarstellung einen Längsschnitt des erfindungsgemäßen Kontaktsystems, und

Fig. 11

in Schnittdarstellung einen Querschnitt des erfindungsgemäßen Kontaktsystems.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Show in it:

Fig. 1

a schematic representation of a circuit with a direct current source and a consumer as well as a circuit breaker connected in between,

Fig. 2

a perspective view of a mechanical contact system of the circuit breaker in an embodiment not according to the invention,

Fig. 3

a sectional view of the non-inventive contact system,

Fig. 4

a perspective view of the non-inventive contact system,

Fig. 5

a side view of the non-inventive contact system,

Fig. 6

in plan view with a view of an underside the contact system not according to the invention,

Fig. 7

a perspective view of an embodiment of the contact system according to the invention in a closed position,

Fig. 8

a perspective view of the alternative embodiment of the contact system according to the invention in an open position,

Fig. 9

a side view of a detail of the contact system according to the invention in the alternative embodiment,

Fig. 10

a sectional view of a longitudinal section of the contact system according to the invention, and

Fig. 11

a sectional view of a cross section of the contact system according to the invention.

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

The Fig. 1 shows a schematic and simplified representation of a circuit 2 for carrying a (direct) current I. The circuit 2 has a direct current source 4 with a positive pole 4a and a negative pole 4b, between which an operating voltage U is present. A load or consumer 6 is connected to the circuit 2. A circuit breaker 8, for example in the form of a hybrid power relay, is connected between the positive pole 4a and the load 6.

The circuit breaker 8 is, on the one hand, connected to a source-side and therefore current-carrying power line by means of a feed connection 10, and, on the other hand, is connected to the power line leaving the load side by means of a load connection 12.

The circuit breaker 8 has a series connection of a hybrid isolating device 14 and a fuse 15. The isolating device 14 is designed with a hybrid switch 16, which has a mechanical contact system 18 and a series connection of a semiconductor switching system 20 and an (auxiliary) relay 21 connected in parallel. The semiconductor switching system 20 is in the Fig. 1 shown by way of example by means of a controlled power semiconductor switch, in particular by means of an IGBT (Insulated Gate Bipolar Transistor).

The additional relay or isolating element 21 ensures galvanic isolation of the current path 2 when the isolating device 14 is triggered. The isolating device 14 is suitable and set up to safely carry the current I for a sufficiently long time in the event of a fault or overcurrent until the fuse 15 triggers. Safe carrying of the current I means in particular that the contacts of the mechanical contact system 18 are not interrupted or lifted.

Below is based on the Fig. 2 to Fig. 6 an embodiment of the contact system 18 not according to the invention is explained in more detail.

That in the Fig. 2 Contact system 18 shown has two stationary fixed contacts 22a, 22b, which are connected to the feed connection 10 on the one hand and on the other hand are electrically conductively connected to the load connection 12. The fixed contacts 22a, 22b are each guided to an associated electrical connection 23a, 23b, by means of which the contact system 18 can be connected to the circuit 2.

The contact system 18 also has two moving contacts 24a, 24b, which are carried by a common, current-carrying contact bridge 26. The contact bridge 26 is coupled to a drive system 28, by means of which the contact bridge 26 can be moved toward or away from the fixed contacts 22a, 22b.

To switch the contact system 18, the contact bridge 26 can be moved from an open position to a closed position by means of the drive system 28 in the course of a switching movement. In the Figures 2 to 6 the contact system 18 is shown in the closed position, in which the moving contacts 24a, 24b at the respective contact points are in electrically conductive contact with the respective opposite fixed contact 22a, 22b.

In the exemplary embodiment Figures 2 to 6 The switching movement caused by the drive system 28 when opening and closing the contact system 18 takes place linearly along an (adjusting) direction of the drive system 28 that is oriented perpendicular to the contacts 22a, 22b, 24a, 24b.

The elongated, straight, approximately plate-shaped contact bridge 26 is made, for example, as a stamped part made of copper. The moving contacts 24a and 24b are arranged on the opposite end faces of the approximately rectangular contact bridge 26. The moving contacts 24a and 24b are arranged on the flat surface or underside 30 of the contact bridge 26 facing the fixed contacts 22a and 22b. The drive system 28 is arranged on the oppositely arranged plan side or surface 32 of the contact bridge 26.

The Fig. 3 shows a sectional view of a detail of a longitudinal section of the contact system 18 along line III-III Fig. 2 . As in the sectional view of the Fig. 3 is comparatively clearly visible, the drive system 28 a spring-loaded stamp 34 for actuating or moving the contact bridge 26.

The stamp 34 is at least partially surrounded by a spring element 36 designed, for example, as a coil spring, which is also referred to below as a contact compression spring. The contact pressure spring 36 is arranged in such a way that in the closed position there is at least a certain spring tension, the restoring force of which acts as a contact force Fk or contact pressure on the contact bridge 26, and thus on the moving contacts 24a and 24b ( Fig. 4 ). In other words, the moving contacts 24a and 24b are subjected to a contact pressure or contact pressure by means of the drive system 28, which ensures a secure contact of the contacts 22a, 22b, 24a, 24b. The contact force Fk is oriented along the positioning or actuation direction of the drive system, i.e. along the direction along which the linear switching movement of the contact system 18 takes place.

A magnetic element 38 is arranged on the contact bridge 26. The magnetic element 38 is designed as an approximately horseshoe or U-shaped magnetic yoke, the horizontal U-leg 38a of which is arranged on the top 32 of the contact bridge 26. The U-leg 38a has a central, unspecified, circular recess through which the stamp 34 is guided at least in sections. The U-leg 38a is arranged transversely, i.e. essentially perpendicularly, to the contact bridge 26.

A vertical U-leg 38b is formed on the opposite end faces of the U-leg 38a. The U-legs 38b are oriented perpendicular to the U-leg 38a and to the contact bridge 26, i.e. essentially parallel to the stamp 34. The U-legs 38b encompass the contact bridge 26, so that the U-legs 38b at least partially protrude axially at their respective free ends of the underside 30 of the contact bridge 26, i.e. protrude beyond the underside 30. A second magnetic element 40 is arranged at a distance from the free ends of the U-legs 38b. This is designed as a flat, approximately rectangular anchor plate Magnetic element 40 is arranged parallel to the U-leg 38a, i.e. transversely to the contact bridge 26.

In the closed position shown in the figures, the free ends of the U-legs 38b are each held at a distance from the anchor plate 40 by means of an air gap 42. The anchor plate 40 is arranged stationary, i.e. fixed to the housing with respect to a housing of the isolating device 14 or the circuit breaker 8. The magnetic yoke 38 and the anchor plate 40 are each made of a soft magnetic material, in particular a soft magnetic iron material.

The U-legs 38b point - as in particular in the Fig. 4 and Fig. 5 can be seen - an approximately funnel-shaped cross-sectional shape in the plane spanned by the longitudinal directions of the U-legs 38b and the contact bridge 26. The U-leg 38b has a truncated cone or trapezoidal area, which is formed on the base of the U-leg 38a, and an approximately rectangular area, which is formed on the base side of the trapezoidal area opposite the base. The rectangular area forms the free end of the U-leg 38b. In the U-leg 38b can, for example, in Fig. 4 shown, a circular recess 44 may be introduced.

As especially in the in Fig. 6 As can be seen from the top view shown with a view of the underside 30, the anchor plate 40 has an approximately hourglass-shaped, i.e. waisted, cross-sectional shape in the plane spanned by the longitudinal directions of the contact bridge 26 and the U-leg 38a. The waist or taper is arranged centrally along the respective long side and in the area of the fixed contacts 22a and 22b.

Like in the Fig. 4 is indicated schematically by arrows, the electrical current I is fed into the contact bridge 26 via the fixed contact 22a and the moving contact 24a and removed from the contact system 18 via the moving contact 24b and the fixed contact 22b. Due to magnetic effects occurs through the Contact pairs 22a, 24a and 22b, 24b each have a tightening force Fe, which is oriented in the opposite direction to the contact force Fk.

The contact force Fk, i.e. the spring strength of the contact compression spring 36, is in particular dimensioned such that in the case of a normal current, i.e. an electrical current I which has a current strength less than or equal to a normal or nominal value, the constriction force Fe is reliably compensated. This means that the contact force Fk is always greater than the tightening force Fe at a normal current, so that undesired lifting of the moving contacts 24a, 24b from the fixed contacts 22a, 22b is reliably and easily prevented.

The magnetic elements 38 and 40 prevent the narrowing force Fe from separating the contacts 22a, 22b, 24a, 24b from one another in the event of a fault or overcurrent in which the current intensity of the current I exceeds the nominal value. In the event of such an overcurrent, the contact force Fk of the contact compression spring 36 is not sufficient to reliably compensate for the increasingly increasing constriction force Fe.

When a current flows through the contact bridge 26, the current I generates a magnetic field around the contact bridge 26. The magnetic field polarizes the soft magnetic magnetic yoke 38 and the soft magnetic anchor plate 40, whereby the magnetic flux density in the area of the magnetic elements 38, 40 is significantly increased compared to the surroundings. A magnetic circuit is thus formed between the magnetic yoke 38, the air gap 42 and the armature plate 40.

The spacing by means of the air gap 42 thus causes an attractive magnetic force Fm between the magnetic yoke 38 and the anchor plate 40. Since the anchor plate 40 is arranged stationary or fixed to the housing in the circuit breaker 8, the magnetic yoke 38 is pulled onto the anchor plate 40. The resulting magnetic force Fm is therefore aligned in the same direction as the contact force Fk of the contact compression spring 36, so that the magnetic force Fm and the contact force Fk add up to a resulting total force, which counteracts the tightness force Fe.

The contact pressure between the contacts 22a, 22b, 24a, 24b is thus increased, which reliably and reliably counteracts the lifting of the contacts 22a, 22b, 24a, 24b, even in the event of a fault or overcurrent.

The current-carrying contact bridge 26 thus generates a magnetic field that supports the drive system 28 and is used to increase the contact pressure. When current flows through the contact bridge 26, the magnetic elements 38, 40 thus act as an additional electromagnetic actuator or lifting magnet, the magnetic force Fm of which acts directly on the contact bridge 26 and thus on the moving contacts 24a, 24b via the U-leg 38a.

Below is based on the Fig. 7 to Fig. 11 an embodiment of the contact system 18 'according to the invention is explained in more detail.

In this embodiment, the contact bridge 26' is designed as a substantially U-shaped copper part, with the two moving contacts 24a, 24b each being arranged at a free end of a vertical U-leg 26'a.

A magnetic element 38' designed as an anchor plate is arranged along the vertical U-legs 26a' of the contact bridge 26'. The drive system 28' of the contact device 18' is designed in this exemplary embodiment as a hinged armature magnet system, with only an approximately U-shaped spring element 46 coupled to the hinged armature being shown. The U-legs 26'a and the anchor plates 38' as well as the U-legs 46a are essentially each arranged stacked in a row.

The vertical U-legs 46a of the spring element 46 are arranged essentially aligned with the U-legs 26a' of the contact bridge 26', the horizontal U-leg 46b of the spring element 46 being spaced apart from the horizontal U-leg 26'b of the contact bridge 26'. is arranged. In other words, the U-legs 46a have a greater length along the longitudinal direction of the leg as the U-legs 26'a, so that the U-leg 46b is arranged above the U-leg 26'b along the longitudinal direction of the leg.

The spring element 46 is made of a flexible material, for example spring steel, so that pivoting or rotational mobility of the drive system 28 'is realized by the essentially free-standing U-leg 46b. In particular, the U-legs 46a of the spring element 46 are thus held pivotably or rotatably relative to a pivot or rotation axis S running parallel to the U-leg 46b.

In this exemplary embodiment, the switching movement takes place in particular by pivoting the contact bridge 26 'around the pivot axis S. This pivoting movement is in the Fig. 7 , which shows the contact system 18 'in a closed position, and in the Fig. 8 , which shows the contact system 18 'in an open position, indicated. The pivoting or rotating movement creates comparatively large separation distances between the contacts 22a, 22b, 24a, 24b.

In this exemplary embodiment, two stationary magnetic elements 40 'are provided, which are arranged fixed to the housing on an insulating, i.e. electrically non-conductive, housing 48 of the circuit breaker 8. The magnetic elements 40' are designed in cross section as horseshoe or U-shaped magnet yokes, which extend at least in sections along the longitudinal direction of the U-legs 26'a, 46'. The magnet yokes 40' are therefore essentially designed as cylindrical molded parts with a horseshoe or U-shaped base or cross-sectional area.

The magnetic elements 40' each have a horizontal U-leg 40a' which is oriented parallel to the U-legs 26'a, 46' in the closed position. Two vertical U-legs 40'b are formed on the back-like U-leg 40a' of the magnet yoke 40'. The U-legs 40'b of the magnet yoke 40' encompass - as in, for example Fig. 9 visible - in the closed position, at least in sections, the vertical U-legs arranged opposite each other 26'a of the contact bridge 26', so that the air gap 42 is formed between the free ends of the U-legs 26'a and the respective anchor plate 38'.

As shown in the sectional views of the Fig. 10 and the Fig. 11 As can be seen, the current I generates a magnetic field B when it flows through the legs 26'a, 26'b of the contact bridge 26', which, regardless of the direction of the current, causes the magnetic force Fm that attracts the magnetic elements 38', 40' to one another, whereby the contact force Fk due to the spring tension the spring element 46 is reinforced.

Reference symbol list

2

circuit

4

DC power source

4a

positive pole

4b

negative pole

6

Load/Consumer

8th

Circuit breaker

10

Feed connection

12

Load connection

14

Separating device

15

Backup

16

Hybrid switch

18, 18'

Contact system

20

Semiconductor switch system

22a, 22b

Fixed contact

23a, 23b

Connection

24a, 24b

Moving contact

26

Contact bridge

26'

Contact bridge

26'a, 26'b

U-thigh

28.28'

Drive system

30

Plane surface/underside

32

Plane surface/top

34

Rubber stamp

36

Spring element/contact compression spring

38

Magnetic element/magnetic yoke

38a, 38b

U-thigh

38'

Magnetic element/anchor plate

40

Magnetic element/anchor plate

40'

Magnetic element/magnetic yoke

40'a, 40'b

U-thigh

42

air gap

44

recess

46

Spring element

46a, 46b

U-thigh

48

Housing

U

Operating voltage

I

Electricity

Fk

Contact force

Fm

Magnetic force

Fe

tightness

S

Swivel axis/rotation axis

b

Magnetic field

Claims (5)

1. Disconnecting device (14) for DC interruption of a current path (2), in particular for a circuit breaker (8), comprising a hybrid switch (16), which has a current-carrying mechanical contact system (18') and a semiconductor switching system (20) connected in parallel therewith,

   - wherein the contact system (18') comprises at least one stationary fixed contact (22a, 22b) and at least one moving contact (24a, 24b), and

   - wherein said moving contact (24a, 24b) is connected to a drive system (28'), which moves the moving contact (24a, 24b) during a switching movement from an open position to a closed position, in which a contact force (Fk) is applied to the fixed contact (22a, 22b),
   characterized in

   - that at least one first magnetic element (38') is arranged on the contact bridge (26'), which first magnetic element (38') is spaced apart from a static second magnetic element (40') by means of an air gap (42) in such a way that, when a current flows through the contact bridge (26'), a magnetic field (B) is produced in the first magnetic element (38') and a magnetic attraction (B) of the first and second magnetic elements (38', 40') occurs, the attraction causing a magnetic force (Fm), which is in the same direction as the contact force (Fk),

   - that the contact bridge (26') is substantially U-shaped, wherein two moving contacts (24a, 24b) each are arranged at a free end of a vertical U-leg, and

   - that the switching movement of the contact bridge (26') is a pivoting or rotating movement along or parallel to the horizontal U-leg (26'b).
2. Disconnecting device (14) according to claim 1,
   characterized in
   that the mechanical contact system (18') has two fixed contacts (22a, 22b) and two moving contacts (24a, 24b).
3. Disconnecting device (14) according to claim 1 or 2,
   characterized in
   that the first magnetic element (38') and the second magnetic element (40') are each made of a soft magnetic material, in particular a soft magnetic iron material.
4. Disconnecting device (14) according to one of claims 1 to 3,
   characterized in

   - that along each of the vertical U-legs (26'a) a first magnetic element (38') formed as an anchor plate is arranged, and

   - that two second magnetic elements (40') formed as a magnetic yoke are provided, which are arranged in the region of the fixed contacts (22a, 22b) and which each have two vertical U-legs (40'b), which at least partially embrace the respective oppositely arranged vertical U-leg (26'a) of the contact bridge (26').
5. Circuit breaker (8) with a disconnecting device (14) according to one of claims 1 to 4.

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