EP2286432B1 - Electric selective automatic switch - Google Patents

Description

The invention relates to an electrical selective self-switch, in particular a circuit breaker. It particularly relates to an electrical selective circuit breaker with low power losses.

An electrically selective self-switch is out of the EP-A-1365432 known.

An electrical self-switch is for example from the DE 103 54 505 A1 known. Meets in this known electrical self-switch of the plunger of the magnet armature in the direction of actuation on the contact bridge, it is not only an interruption of the main current paths, but also a brief interruption of the auxiliary current paths through the resulting elastic shock. This can lead to the function of the auxiliary release device is not reliably guaranteed.

From the DE 28 54 616 is a selective protection device known, which serves for selective shutdown of consumers, possibly with an upstream main fuse. Here, in the current path of a main line circuit breaker, a switching device is provided, which at least partially switches the current on a provided with a magnetic release parallel branch when a short-circuit current, the parallel branch includes a device which after passing a predetermined value of a temporal square integral current through the coil of the Magnetic release increased so much that this triggers a switch lock, which finally opens a separation point in the current path of the main circuit breaker.

From the DE 41 183 77 A1 a circuit breaker is already known, the only temporarily shuts off in the event of a short circuit and waits for a downstream circuit breaker to disconnect the short circuit. In this case, it turns on again, otherwise it turns off permanently. For this purpose, a circuit breaker is provided, in whose main current path an overcurrent responsive thermal release such as a bimetal, a responsive short-circuiting magnetic mechanism and actuated by the thermal release and by the magnetic mechanism separation point are arranged. The magnetic mechanism and the separation point are bridged by a Nebenstromweg, in which a second thermal release such as a second bimetal, an electrical resistance and a second separation point are arranged. Behind the separation points, another current path branches off to the neutral conductor via a second magnet mechanism, it leads behind the second magnet mechanism via two parallel lines each having a third separation point and a fourth separation point, the first branch current still having a second resistance.

In addition, main circuit breakers according to E DIN VDE 0645 are known in which in a main current path a first thermal trip device such as a bimetal, a main switch and a magnetic trip device are connected in series, the main switch is bridged by a shunt, in which a selective resistor , a second thermal trip device for selective trip and a sub-switch are connected in series, the first thermal trip device and the second thermal trip device acting on a derailleur, which opens the main switch and the sub-switch, and wherein the magnetic tripping device acts on the main switch.

The object of the present invention is to provide an electrical selective self-switch in which, on the one hand, it is reliably ensured that an uninterrupted flow of current in the auxiliary current path is ensured when the main tripping device is actuated, ie if the main current path is interrupted, and at the same time the power losses during normal operation are minimized.

This object is achieved by the electrical selective self-switch according to claim 1. Advantageous embodiments of the invention are specified in the subclaims.

In particular, according to the invention an electrical selective self-switch, in particular a circuit breaker is provided with a series circuit of an auxiliary trip device, a normally closed first switch, a resistor and a main tripping device, which is connected between a first and a second electrical connection, a bypass current path, the main tripping device is connected in series between the first and the second electrical connection and having a closed in the event of trouble second switch and a normally closed third switch, the second switch is connected in series, and a current bridge connecting an input contact of the first switch with a connection contact between the second and the third switch, wherein the main triggering device is designed so that upon reaching a first threshold current of the second switch and upon reaching a second threshold current, is larger than the first threshold current, in addition, the third switch is opened, and wherein the auxiliary triggering device is designed such that the first and the third switch is opened when the second switch is open after a first period of time, while with the second and third switches open the first switch is opened after a second period of time, which is shorter than the first time period.

In other words, according to the invention there is provided an electrical selective self-switch, which can be used in particular as a circuit breaker, which has a first and a second parallel circuit, which are connected in series with each other and with a main tripping device. Here, the first parallel circuit in its first branch on an auxiliary tripping device and a series-connected normally closed first sub-switch of a double switch, wherein its second branch forms a shunt with a normally closed first switch. The second parallel circuit has in its first branch a normally closed second partial switch of the double switch and a resistor connected in series, its second branch forming a shunt with a normally closed second switch. The main triggering device is designed so that upon reaching a first threshold current of the first switch and on reaching a second threshold current, which is greater than the first threshold current, in addition, the second switch is opened. The auxiliary trip device is designed so that the first and second part switches of the double switch and the second switch at an open first switch after a first period of time and at an open second switch after a second time period which is shorter than the first time period is opened ,

In a practical embodiment of the invention, it is preferred that the current bridge is formed by a contact bridge, which in the operating state a first and a second fixed contact of the first switch and a third fixed contact of the third switch electrically connects to each other.

In order to ensure that the first switch is basically only opened by the auxiliary trip device in order to ensure uninterrupted current flow in the auxiliary current path, it is advantageous if the third fixed contact on the one hand and the first and second fixed contact on the other hand are located on opposite sides of the contact bridge ,

In a preferred embodiment of the invention, the auxiliary tripping device comprises a Bimetallbetätigereinrichtung with a located between the first terminal and the first switch first bimetal, wherein the Bimetallbetätigereinrichtung is formed so that it acts on the contact bridge mechanically acted on switching mechanism, and wherein the switching mechanism on the contact bridge exerted triggering force in the opening direction of the contact between the third fixed contact and the contact bridge and the opening directions of the contact between the first fixed contact and the contact bridge and the second fixed contact and the contact bridge acts.

It is expedient here if the bimetallic actuator device has a second bimetallic located between the first switch and the second connection, which is designed such that it triggers the switching mechanism independently of the first bimetal by means of the bimetallic actuator.

Preferably, the arrangement of the first fixed contact and the second fixed contact and / or the design of the contact bridge is such that the contact bridge when triggering the switching mechanism, after the third fixed contact has been opened, first separated from the second fixed contact and then from the first fixed contact. This embodiment causes a reliable consecutive separation of the second fixed contact first of the contact bridge and then the first fixed contact of the contact bridge.

For a mechanically safe and simple embodiment of the invention, it is particularly advantageous if the main tripping device has a magnetically actuating device acting mechanically on the contact bridge with a first In the direction of actuation movable magnet armature and a switched between the bypass path and the second coil, wherein the actuating direction of the first armature directed, exerted by the first armature release force in the opening direction of the contact between the third fixed contact and the contact bridge and in the closing direction of the contact between the first Fixed contact and the contact bridge and between the second fixed contact and the contact bridge acts.

In a preferred embodiment of the invention, a connecting line between the first fixed contact and the second fixed contact forms a pivot axis for the contact bridge when the tripping force of the first armature is applied to the contact bridge.

Further, it is preferable if the point of action of the release force exerted by the first armature between the third fixed contact on the one hand and the first and second fixed contact on the other hand.

Furthermore, it is expedient if a contact spring is provided which simultaneously generates contact forces between the third fixed contact and the contact bridge, between the first fixed contact and the contact bridge and between the second fixed contact and the contact bridge in the respective closing direction of the fixed contacts.

It when the contact spring facing away from the second fixed contact, the first and second fixed contact superior portion of the contact bridge acts on it is particularly advantageous.

In this case, it is particularly expedient for the second switch to have a movable contact which, in the event of a malfunction, electrically connects the first terminal to the contact bridge, the movable contact preferably being arranged in the actuating direction of the movable magnet armature behind the contact bridge and being pivotably mounted by means of a pivoting device, wherein the pivot axis of the pivot device extends substantially parallel to the pivot axis of the contact bridge.

For a simple mechanical implementation of the second and third switches of the electrical selective self-switch according to the invention, it is particularly advantageous if the Magnetbetätigereinrichtung has a extending through a through hole of the contact bridge pin with located in the direction of actuation of the movable armature in front of the contact bridge widening, one end the pin of the magnetic actuator is adapted to act in the opening direction of the movable contact on this and the expansion is adapted to act in the opening direction of the contact bridge on this.

In this case, it is expedient for the magnetic actuator device to be configured such that, upon actuation of the first magnet armature, the contact between the contact bridge and the movable contact is opened prior to contacting between the third stationary contact and the contact bridge.

If, in a further advantageous embodiment, the magnetic actuator device has a core which is provided with a short-circuit ring facing the first magnet armature, vibration of the magnet armature is avoided by the eddy currents occurring in the short-circuit ring in the event of a fault or when operating with alternating current. Finally, in a further preferred embodiment, the reliability is increased by the fact that the magnetic actuator has a second movable in the direction of actuation armature, which preferably has a greater mass than the first armature, and in addition to the first armature an accelerated at an increased induction in the magnetic actuator Movement causes in the direction of actuation. By providing the additional second magnet armature, the contact between the contact bridge and the third fixed contact is abruptly opened in the event of a short circuit, ie at high induction in the magnetic actuator as a result of a high overcurrent that an arcing there also increased in the case of this error Current flow is reliably and quickly erased.

Further, it is preferred if the auxiliary triggering device is configured such that upon manual switching on, first the second switch, then the first switch and subsequently the third switch is closed.

• Fig. 1A eine Funktionsskizze des erfindungsgemäßen elektrischen selektiven Selbstschalters und eine detaillierte Ansicht der in der Richtung A hintereinander liegenden ersten und zweiten Festkontakte;
• Fig. 1B ein Schaltbild des erfindungsgemäßen elektrischen selektiven Selbstschalters im störungsfreien Betrieb;
• Fig. 2A eine Funktionsskizze des erfindungsgemäßen elektrischen selektiven Selbstschalters im Falle eines Überstroms;
• Fig. 2B ein Schaltbild des erfindungsgemäßen elektrischen selektiven Selbstschalters im Falle eines Überstroms;
• Fig. 3A eine Funktionsskizze des erfindungsgemäßen elektrischen selektiven Selbstschalters im Falle eines Kurzschlussstroms;
• Fig. 3B ein Schaltbild des erfindungsgemäßen elektrischen selektiven Selbstschalters im Falle eines Kurzschlussstroms;
• Fig. 4A eine Funktionsskizze des erfindungsgemäßen elektrischen selektiven Selbstschalters im abgeschalteten Zustand;
• Fig. 4B ein Schaltbild des erfindungsgemäßen elektrischen selektiven Selbstschalters im abgeschalteten Zustand;
• Fig. 5A eine Funktionsskizze einer weiteren Ausführungsform des erfindungsgemäßen elektrischen selektiven Selbstschalters im störungsfreien Fall; und
• Fig. 5B ein Schaltbild der weiteren Ausführungsform des erfindungsgemäßen elektrischen selektiven Selbstschalters im störungsfreien Fall.
• Fig. 6 ein Schaltbild eines Hauptsicherungsautomaten während der Kurzschlussbeanspruchung mit einem Selektivauslöser und
• Fig. 7 die erfindungsgemäße Anordnung eines Selektivwiderstandes im Magnetkreis einer Schlagspule.

The invention will be explained in more detail by way of example with reference to the drawing; in this shows

• Fig. 1A a Funktionsssizizze the electrical selective self-switch according to the invention and a detailed view of the successive in the direction A first and second fixed contacts;
• Fig. 1B a circuit diagram of the electrical selective self-switch according to the invention in trouble-free operation;
• Fig. 2A a Funktionsssizizze the electrical selective self-switch according to the invention in the event of overcurrent;
• Fig. 2B a circuit diagram of the electrical selective self-switch according to the invention in the case of an overcurrent;
• Fig. 3A a Funktionsssizizze the electrical selective self-switch according to the invention in the case of a short-circuit current;
• Fig. 3B a circuit diagram of the electrical selective self-switch according to the invention in the case of a short-circuit current;
• Fig. 4A a functional diagram of the electrical selective self-switch according to the invention in the off state;
• Fig. 4B a circuit diagram of the electrical selective self-switch according to the invention in the off state;
• Fig. 5A a functional diagram of a further embodiment of the electrical selective self-switch according to the invention in trouble-free case; and
• Fig. 5B a circuit diagram of the further embodiment of the electrical selective self-switch according to the invention in trouble-free case.
• Fig. 6 a circuit diagram of a main circuit breaker during the short-circuit with a Selektivauslöser and
• Fig. 7 the inventive arrangement of a selective resistor in the magnetic circuit of a striking coil.

In Fig. 1A and 1B the construction of the schematically illustrated electrical selective self-switch according to the invention in the switched-on operating state and an associated equivalent circuit diagram are shown. As in Fig. 1B 1, the self-switch according to the invention has a first electrical terminal 2 and a second electrical terminal 4, between which an auxiliary tripping device 6, a first switch 8, a resistor 10 and a main tripping device 12 are connected in series. Furthermore, the electrical selective self-switch according to the invention has a bypass current path which is connected in series with the main tripping device 12 between the first terminal 2 and the second terminal 4 and which has a second switch 14 closed in the event of a malfunction and a normally closed third switch 16 is connected in series with the second switch 14. Furthermore, the input contact of the first switch 8 is connected by a current bridge with a connection contact 18 between the second switch 14 and the third switch 16.

Fig. 1A shows the structure of the electrical selective self-switch according to the invention in the switched-on operating state. Here, a pivotally movable contact bridge 20 connects a first fixed contact 22, which forms the input contact of the first switch 8, a second fixed contact 24 which is connected to the resistor 10, and a third fixed contact 26, which via the bypass current path with the main triggering device 12 in connection stands, electrically with each other. For this purpose, the contact bridge 20 bears against a contact point 28 at its first end 30 on the second fixed contact 26 and establishes an electrical connection between the main triggering device 12 and the first connection 2 via the second switch 14. In the vicinity of its other end 32, the contact bridge 20 is supported via a compression spring 34 against an abutment 38 provided on a switching lock 36. The abutment 38 and the third fixed contact 26 lie on the same side of the contact bridge 20. On the side facing away from this side of the contact bridge 20, this lies in a between the point of the compression spring 34 and the third fixed contact 26 on the first fixed contact 22 and the second fixed contact 24 and thus provides an electrical connection between the first, second and third fixed contact 22, 24 and 26 ago. As in the detailed representation of the Fig. 1A shown, which shows the spatial arrangement of the first fixed contact 22 and the second fixed contact 24 in the direction A perpendicular to the plane of the drawing, the first fixed contact 22 is on the same side of the contact bridge 20 as the second fixed contact 24. Here, however, the second fixed contact 24 slightly further In the operating state, the first contact bridge 20 is supported by the pressure of the spring 34 against the first fixed contact 22 and the third fixed contact 24 and from the force of the spring 34 to a first fixed contact 22nd and the second fixed contact 24 connecting pivot axis X in the detailed representation of Fig. 1A pivoted counterclockwise, so that the first end 30 of the contact bridge 20 is pressed with the contact point 28 against the third fixed contact 26. The compression spring 34 thus brings on all three fixed contacts 22, 24 and 26 a required pressure force, which brings the first contact bridge 20 against the fixed contacts 22, 24 and 26 for fixed abutment.

In addition, the electrical selective self-switch according to the invention has a movable contact 40 which electrically connects the first terminal 2 to the contact bridge 20 in the event of a fault. The movable contact 40 is mounted with its first end 42 in a pivot bearing 44 and is located with a contact point 46 at its second end 48 to the contact bridge 20 at. The pivot axis of the pivot bearing 44 is substantially parallel to the pivot axis X of the contact bridge 20. The movable contact 40 is disposed on the same side of the contact bridge 20 as the first fixed contact 22 and the second fixed contact 24, wherein the movable contact 40 against the contact bridge 20th is pressed by a compression spring 50, which is supported on an abutment 52. The movable contact 40 thus connects the first terminal 2 with the contact bridge 20 and thus forms the closed second switch 14. The third fixed contact 26 opposite a fixed housing stop 54 is provided, to which the first end 30 of the contact bridge 20 during a movement the contact bridge 20 in the clockwise direction against the force of the compression spring 34 abuts to limit a deflection of the contact bridge 20.

In the following, the main triggering device 12 will be described in more detail. This has a coil 56 which is connected in series between the second terminal 4 and the shunt current path to the second switch 14 and the third switch 16. The main tripping device 12, which is designed as a magnetic actuator device or magnet system, further comprises a coil core 58 located within the coil 56, a pin 60 and a first magnet armature 62. In addition, a second armature 64 is provided, which is also displaceable in the release direction B within the coil 56 and acts on the pin 60. At rest, the second armature 64 is supported under the force of a compression spring 66 against a stop 68 fixed to the housing. Furthermore, the core 58 is provided on its side facing the first armature 62 end face with a short-circuit ring 70, wherein formed in the short-circuit ring 70, which is made of a highly electrically conductive material, eddy currents that prevent the formation of vibrations in the main triggering device 12 so that there is no unwanted noise. This is particularly advantageous in AC operation, since then the armature is held vibration-free at the core 58 during the triggering of the self-switch.

The pin 60 is axially slidably mounted within the core 58 in the release direction A and is biased by the compression spring 66 against the release direction B. The forward end of the pin 60 protrudes axially from the core 58 toward the contact bridge 20 and the movable contact 40 and forms a striker for actuating the movable contact 40, the point of action of the pin 60 between the pivot bearing 44 of the movable contact 40 and the compression spring 50 is located. In this case, the pin 60 extends through a through hole 72 of the contact bridge 20, wherein at the front end of the pin 60 in the direction of actuation B of the first armature 62 in front of the contact bridge 20, a widening or an enlarged diameter portion 74 is arranged, which is larger than that Through hole 72 of the contact bridge 20 is. Upon movement of the pin 60 in the direction of actuation B of the magnet armature 62, the widening 74 abuts against the contact bridge 20 to this about the pivot axis X, which is formed by the first and second fixed contact 22 and 24 against the force of the compression spring 34 counterclockwise to move and to open the contact of the contact bridge 20 with the third fixed contact 26. The widening 74 is arranged on the pin 60 such that first the contact between the movable contact 40 and the contact bridge 20 is opened before the contact between the contact bridge 20 and the third fixed contact 26 is opened.

The rear end of the pin 60 is supported in a blind hole of the second armature 64 against the first armature 62 from. The pin 60 penetrates an axial bore in the first armature 62. The first magnet armature 62 is axially displaceably guided within the blind hole of the second armature 64 and is supported on its side facing away from the magnet armature 64 against a collar 75 of a portion of the pin 60 with an enlarged diameter from.

In the following, the auxiliary release device 6 will now be described. This has a Bimetallbetätigereinrichtung with a first bimetal 76, which is connected between the first terminal 2 and the first fixed contact 22 of the first switch 8. In a current flowing through the auxiliary current path, the first bimetal 76 is heated and bends with it, whereupon the switching mechanism 36 is triggered in a known manner after a delay time correlated with the current intensity. In the case of triggering the switching mechanism 36, the switching mechanism 36 moves in the direction of in Fig. 4A shown arrow C, wherein the second end 32 of the contact bridge 20 pivots in a clockwise direction about the axis X until the first end 30 comes to rest against the housing fixed against the third fixed contact 26 stop 54. During this movement of the switching mechanism 36 and the abutment 38 is moved in the direction of the arrow C, so that the pivotal movement of the contact bridge 20 without compression of the spring 34 takes place, so the force of the spring 34 does not increase additionally.

If the first end 30 of the contact bridge 20 abuts the stop 54, the further movement of the switching mechanism 36 in the direction of the arrow C causes the contact bridge 20 to come away from the first fixed contact 22 and from the second fixed contact 24, so that the first switch 8 opens becomes. In this case, when the positioning of the first fixed contact 22 and of the second fixed contact 24 is offset in the release direction C, first the second fixed contact 24 can be detached from the contact bridge 20, after which the first fixed contact 22 is detached from the contact bridge 20, so that the circuit is finally disconnected ,

Now, the function of the electric selective self-switch according to the invention will be described in detail.

Occurs in an accident, an overcurrent between the first terminal 2 and the second terminal 4 via the low-resistance shunt path, the coil 56 induces a magnetic force on the first armature 62, the latter in the release direction B against the force of the spring 66 against the collar 75th the pin 60 moves and then the pin 60 against the force of the spring 66 in the release direction B against the movable contact 40 in its point of action, whereby the contact between the movable contact 40 and contact bridge 20 is opened, as in FIGS. 2A and 2B shown. Here, the extension 74 is attached to the pin 60 so that the contact bridge 20 still forms a contact with the third fixed contact 26 and is not opened. For the in Fig. 2B shown equivalent circuit diagram, this means that the second switch 14 is opened, while the first switch 8 and the third switch 16 remain closed. Thus, in the event of overcurrent, the bimetal 76 of the bimetallic actuator of the auxiliary trip device 6 is connected in series with the coil 56 of the main tripping device 12 and a parallel circuit of resistor 10 and a shunt current path with the third switch 16 shorting the resistor 10 by this shunt current path. Here, the current flowing through the first bimetal 76 leads to a heating of the first bimetal 76, whereby after a first period of time the switching mechanism 36 is opened in the manner described above. In this case, the overcurrent corresponds to a first threshold current, which is adjustable in terms of apparatus (for example, by a corresponding dimensioning of the ratio between the spring force of the spring 66 and the force of the coil 56) by the electrical selective self-switch.

In the event of a short-term overshoot of the first threshold current below the first time period, the contact between the movable contact 40 and the contact bridge 20 is closed again, whereby the first bimetal 76 is again short-circuited by the shunt current path with the first switch 14. Thus, it comes with a short-term increase in the operating current not to trigger the switching mechanism 36. This function has the purpose that the electrical selective self-switch can be provided as a main switch, with an occurrence of an overcurrent first by lying after the main switch fuses of End consumers can be eliminated without the working as a main switch electrical selective selector switch disconnects the entire supply of a variety of end users.

In the case of a short-circuit current, however, the electrical selective self-switch is intended to actuate the switching mechanism 36 within a very short time, that is to say a second time duration, which is substantially shorter than the first time duration. This case is in the FIGS. 3A and 3B shown. Due to a short-circuit current, which in addition to the movable contact 40 by means of the expansion 74, the contact bridge 20 moves in the direction of actuation B and thus the contact between contact bridge 20 and third fixed contact 26 is opened, there is an opening of the second switch 14 as well as the third switch 16, as in the equivalent circuit diagram in FIG Fig. 3B is shown. Thus, the short-circuit current flows via the first bimetal 76, the first switch 8 and the current-limiting resistor 10 via the coil 56 to the second terminal 4. The short-circuit current causes a sudden heating of the first bimetal 76, whereby the switching mechanism 36 is actuated immediately. Here, the second armature 64 in the case of a short-circuit shutdown has the task to open the third fixed contact 26 abruptly directly to a Kontaktöffnungsweg without the interposition of any Kinematikteile sufficient to effectively limit the acting on the third fixed contact 26 arc current, so that the arc safely is deleted. In the event of the occurrence of a high short-circuit current, therefore, the second magnet armature 64 is abruptly moved in the release direction B and acts on the system of the rear end of the pin 60 directly on the pin 60 and shifts it in the triggering direction abruptly against the contact bridge 20th

In the Figs. 5A and 5B is shown a further embodiment of the electrical selective self-switch according to the invention. Here, the auxiliary tripping device 6 on a Bimetallbetätigereinrichtung having in addition to the first bimetal 76, a second bimetal 78 which is formed so that it causes independent of the first bimetal 76 by means of the Bimetallbetätigereinrichtung triggering the switching mechanism 36. The second bimetal 78 is in this case connected between the second fixed contact 24 and the coil 56. The second bimetal 78 thus becomes active only in the event of a short circuit or when a second threshold current is exceeded, since below one second threshold current, the second bimetal 78 and the resistor 10 is shorted by the shunt current path to the third switch 16. Here, the second bimetal 78 has the function that it opens the switching mechanism 36 with a time constant, which is substantially smaller than the time constant of the first bimetal 76th

The present invention thus provides an electrical selective self-switch which selectively opens in the event of an overcurrent occurring after a period of time sufficient for subsequent electrical self-switches of end-users to shut off before the main switch operating as an electrical selective self-switch turns off, and which in Case of a short-circuit current abruptly the contact between the first terminal 2 and second terminal 4 separates. Here, the electric self-switch according to the invention has the advantage that in normal operation, the current between the first terminal 2 and second terminal 4 substantially only flows through the coil 56 of the main triggering device 12, since the first bimetal 76 or the second bimetal 78 through the bypass current path with the second Switch 14 and the third switch 16 are short-circuited. Thus, the power consumption of the electric selective self-switch according to the present invention is minimized. Furthermore, the electric selective self-switch of the present invention has the advantage that before switching off by the switching mechanism 36, an uninterrupted flow of current in an auxiliary current path for controlling the switching mechanism 36 is ensured, whereby a fault in the function of the auxiliary release device is avoided.

In the following, an advantageous embodiment of the resistor 10 and the coil 56 will be described, based on the 6 and 7 to better illustrate the principle of operation by a simplified main circuit breaker will be explained. However, the arrangement and configuration of the selective resistor 101 and the beating coil 102 are applicable to a resistor 10 configured as a coil and the coil 56.

For current limiting in the event of a short circuit, resistors in the range of 0.5 ohms are used in the main circuit breaker.

During the turn-off time of a few tens of milliseconds, the selective resistor has to be able to handle powers of the order of 100 kilowatts non-destructively.

This requires considerable dimensions of the selective resistance as z. In the European application WO 03/065398 A1 is described in detail. There, a resistor body of doped ceramic is recommended as a selective resistor. In addition to coils wound from resistance wire, folded or wound current limiting resistors are known as flat strips of resistance material.

Apart from the measures which are required to avoid the unwanted magnetic field of such arrangements, the space in "miniature circuit breakers" is often not available.

Basically disadvantageous is that the magnetic field of the bobbin in short circuits of z. B. 5 times rated current is sufficient to open the main contact, but not keep it open during the delayed shutdown. Due to the current limiting of the selective resistor, the current in the impact coil is reduced to approximately 3 times the rated current - the magnetic excitation is no longer sufficient to hold the armature against the force of the closing spring of the main contact. The consequence of this is that the main contact closes momentarily to reopen immediately. This alternating process, referred to in the art as "woodpeckers", is undesirable.

According to the invention therefore comes a selective resistance, which in the Fig. 1 to 5 shown resistor 10, for use, which is wound as a coil of resistance material, over the bobbin of the main circuit, which may be the coil 56, is arranged.

As a result, the use of the free space between the bobbin and the housing walls of the main circuit breaker for accommodating the selective resistor is possible.

By this simple measure is achieved that by the additional number of turns of the selective resistor in series with the impact coil even with limited residual current greater flux in the magnetic circuit is available as the operating current of the electromagnet. The magnet armature keeps the main contact safely open during the delay time and that until the Selective bimetal unlocks the switch lock of the main circuit breaker and this interrupts the circuit.

The Selektivauslöser forms together with the impact coil a structural unit, which is enclosed by a common magnetic yoke and additionally has a magnetic core, a magnet armature and a selective bimetal.

Preferably, the magnetic yoke is formed so that it not only serves to conduct the magnetic flux, but also acts as a magnetic and thermal shield against adjacent devices. The magnetic yoke, which also carries the selective bimetal, encloses on four sides in a box-shaped manner both the impact coil and the coil-shaped selective resistance and is spatially arranged on both sides between the latter and the housing walls of the main automatic circuit breaker.

It is advantageous if the complete selective release, so housed together with the impact coil on the same side in the energy flow direction of main and break contact circuit technology.

In addition, the winding direction of selective resistance and impact coil is chosen so that complement their magnetic effect in current flow.

In Fig. 6 is the arrangement of the selective resistor 101 on the impact coil 102 can be seen from the circuit diagram of the main circuit breaker. Likewise, the circuit-technical position of the selective release can be recognized as a parallel circuit. The illustrated switching state corresponds to the fault case "short circuit" during the delay time.

When switched on, the main contact 103 and the isolating contact 104 are closed. The operating current flows through the main contact 103 and the impact coil 102 to the electrical load.

In the event of a fault in the event of a short circuit, it opens in the Fig. 7 represented armature 105, energized by the magnetic field of the beating coil 102, the main contact 103rd

The isolating contact 104 remains closed, so that the main contact 103 is bridged by the parallel circuit of the selective release.

In this case, the short-circuit current is limited by the selective resistor 101.

This residual current flows through both the selective bimetal 106 and through the selective resistor 101 and the impact coil 102. The residual current generates an additional, magnetic induction in the selective resistance, which strengthens both the tightening force of the armature 105 when opening the main contact 103 in the magnetic circuit of the beating coil also ensures a sufficient holding force of the armature 105 on the magnetic core 108 during the delay time.

During this time, the selective bimetal 106 bends and unlatches the switching mechanism, which then opens the isolating contact 104, the main contact 103 is kept open and thus interrupts the circuit to be protected. If during the delay time the circuit elsewhere, so z. B. is interrupted by a downstream circuit breaker, the main circuit breaker remains switched on and ensures the availability of the rest of the system.

In Fig. 7 schematically is a horizontal section through the main circuit breaker shown in plan view. From this, the spatial arrangement of the selective resistor 101 can be seen over the impact coil 102 and the formation of the magnetic yoke 107 as a thermal and magnetic shield within the housing 110 relative to adjacent devices recognizable.

In the event of a fault, the flux in the magnetic circuit is generated both by the number of turns of the selective resistor 101 and by the windings of the beating coil 102, so that the residual current limited by the selective resistance is certainly sufficient for the armature 105 during the delay time to hold the magnetic core 108 and thus to fix the main contact 103 against the force of the closing spring 109 in the open position.

Thus, therefore, a Selektivauslöser is provided for a main circuit breaker, which is arranged in series connection of selective bimetal and selective resistor as a parallel circuit to the main contact and bridges this in the event of a fault "short circuit". The selective resistor 101 is formed as a coil and arranged in the magnetic circuit of the beating coil 102 for their magnetic assistance in the force effect when opening and keeping open the main contact 103.

The selective resistor 101 limited in functional combination both the short-circuit current and amplified with the remaining residual current, the flooding in the magnetic circuit together with the impact coil 102nd

The selective resistor 101 is arranged spatially between the magnet yoke 107 and the impact coil 102, enclosing and covering it at least partially.

The selective release is circuitally arranged together with the impact coil 102 on the same side in the energy flow direction of the main contact 103 and isolating contact 104.

The Selektivauslöser forms together with the impact coil 102, the magnetic core 108, the armature 105, the selective resistor 101, the Selektivbimetall 106 and the yoke 107 a structural unit, wherein the yoke which on the housing walls 110 over a large area abuts the attachment for the base of the Selektivbimetalles 106th offers.

The arrangement of the formed as a coil of selective resistance 101 to the impact coil 102 is according to the invention in the Fig. 1 to 5 shown resistor 10 and the coil 56 applicable.

Claims (18)

1. Electric selective automatic switch, with

   - a serial connection comprising an auxiliary tripping device (6), a normally closed first switch (8), a resistor (10) and a main tripping device (12), which is connected between a first and a second electrical connection (2, 4),

   - a shunt current path, which is connected in series to main tripping device (12) between first and second electrical connection (2, 4), and which comprises a second switch (14), closed in a fault-free event, characterised in that the automatic switch comprises a normally closed third switch (16), which is connected in series to second switch (14), and

   - a current bridge, which connects an input contact of first switch (8) to a connection contact (18) between second and third switch (14, 16),
   wherein main tripping device (12) is designed such that, on reaching a first threshold current, second switch (14) is opened, and on reaching a second threshold current, which is greater than the first threshold current, third switch (16) is additionally opened, and
   wherein the auxiliary tripping device (6) is designed such that, when second switch (14) is open, first and third switch (8, 16) are opened after a first period of time has elapsed, while, when second and third switch (14, 16) are open, first switch (8) is opened after a second period of time has elapsed, which is shorter than the first period of time.
2. Electric selective automatic switch according to Claim 1, characterised in that the current bridge is formed by a contact bridge (20), which, in the operating state, electrically connects together a first and a second fixed contact (22, 24) of first switch (8) and a third fixed contact (26) of third switch (16).
3. Electric selective automatic switch according to Claim 1 or 2, characterised in that third fixed contact (26) on one hand and first and second fixed contact (22, 24) on the other hand are placed on opposite sides of contact bridge (20).
4. Electric selective automatic switch according to Claim 1, 2 or 3, characterised in that auxiliary tripping device (6) has a bimetal actuator device with a first bimetal (76) placed between first connection (2) and first switch (8), wherein the bimetal actuator device is designed such that it acts on a switch latch (36) mechanically impinging on contact bridge (20) and wherein the tripping force exerted by switch latch (36) on contact bridge (20) acts in the opening direction of contact-making between third fixed contact (26) and contact bridge (20) and the opening directions of contact-making between first fixed contact (22) and contact bridge (20) and between second fixed contact (24) and contact bridge (20).
5. Electric selective automatic switch according to Claim 4, characterised in that the bimetal actuator device has a second bimetal (78) placed between first switch (8) and second connection (4), second bimetal being designed such that it causes a tripping of switch latch (36) by means of the bimetal actuator device, independently of first bimetal (76).
6. Electric selective automatic switch according to Claim 4 or 5, characterised in that the arrangement of first fixed contact (22) and second fixed contact (24) and/or the configuration of contact bridge (20) is such that, when switch latch (36) trips after third fixed contact (26) has been opened, contact bridge (20) is separated, firstly from second fixed contact (24) and secondly from first fixed contact (22).
7. Electric selective automatic switch according to one of Claims 2 to 6, characterised in that main tripping device (12) has a magnetic actuator device acting mechanically on contact bridge (20), with a first magneto inductor (62) mobile in an actuating direction and a coil (56) connected between the shunt current path and second connection (4), wherein the tripping force exerted by first magneto inductor (62), directed in actuating direction (B) of first magneto inductor (62) acts in an opening direction of contact-making between third fixed contact (26) and contact bridge (20) and in the closing direction of contact-making between first fixed contact (22) and contact bridge (20), and between second fixed contact (24) and contact bridge (20).
8. Electric selective automatic switch according to Claim 7, characterised in that a connecting line (X) between first fixed contact (22) and second fixed contact (24) forms a swivelling axis for contact bridge (20) when the tripping force of first magneto inductor (62) is applied to contact bridge (20).
9. Electric selective automatic switch according to one of Claims 7 to 8, characterised in that the point of action of the tripping force exerted by first magneto inductor (62) lies between third fixed contact (26) on one hand and first and second fixed contact (22, 24) on the other hand.
10. Electric selective automatic switch according to one of Claims 7 to 9, characterised in that a contact spring (34) is provided, which, in the operating state, simultaneously generates contact forces between third fixed contact (26) and contact bridge (20), between first fixed contact (22) and contact bridge (20) and between second fixed contact (24) and contact bridge (20), in the respective closing direction of fixed contacts (22, 24, 26).
11. Electric selective automatic switch according to Claim 10, characterised in that contact spring (34) acts on a section of contact bridge (20), opposite third fixed contact (26), and surmounting first and second fixed contacts (22, 24).
12. Electric selective automatic switch according to one of Claims 2 to 11, characterised in that second switch (14) has a mobile contact (40), which electrically connects first connection (2) to contact bridge (20) in a fault-free event.
13. Electric selective automatic switch according to Claim 12, characterised in that mobile contact (40) is placed behind contact bridge (20) in actuating direction (B) of first magneto inductor (62) and is supported to swivel by means of a swivelling device (44), wherein the swivelling axis of swivelling device (44) runs substantially parallel to swivelling axis (X) of contact bridge (20).
14. Electric selective automatic switch according to Claim 12 or 13, characterised in that the magnetic actuator device has a pin (60) extending through a leadthrough hole (72) of contact bridge (20), with a widening (74) situated in front of contact bridge (20) in actuating direction (B) of first magneto inductor (62), wherein a front end of pin (60) of the magnetic actuator device is configured to act on mobile contact (40) in its opening direction, and widening (74) is configured to act on contact bridge (20) in its opening direction.
15. Electric selective automatic switch according to one of Claims 7 to 14, characterised in that the magnetic actuator device is configured such that on actuating first magneto inductor (62), contacting is opened between contact bridge (20) and mobile contact (40) before contacting is opened between third fixed contact (26) and contact bridge (20).
16. Electric selective automatic switch according to one of Claims 7 to 15, characterised in that the magnetic actuator device has a core (58), which is provided with a short circuit ring (70) facing first magneto inductor (62).
17. Electric selective automatic switch according to one of Claims 7 to 16, characterised in that the magnetic actuator device has a second magneto inductor (64) mobile in actuating direction (B), which preferably possesses a greater mass than first magneto inductor (62), and which, with increased induction in the magnetic actuator device, effects an accelerated movement in actuating direction (B) additionally to first magneto inductor (62).
18. Electric selective automatic switch according to one of the preceding claims, characterised in that the auxiliary tripping device is designed such that with manual switching on, second switch (14) is closed first, then first switch (8), followed thereupon by third switch (16).

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