CIRCUIT BREAKER

Abstract

A circuit breaker having a mechanical switch introduced into a main current path, which comprises a fixed contact and a moving contact connected to a movably mounted contact bridge. The circuit breaker comprises a drive, which is in active connection with the contact bridge, and which comprises a first drive unit and a second drive unit. The first drive unit is energized via a control circuit, and the second drive unit is connected in parallel to a resistor element introduced into the main current path. The invention also relates to a motor vehicle.

Claims

1. A circuit breaker comprising: a mechanical switch introduced into a main current path, which has a fixed contact and a moving contact connected to a movably mounted contact bridge; a drive, which is in active connection with the contact bridge; and a first drive unit and a second drive unit, wherein the first drive unit is energized via a control circuit, and wherein the second drive unit is connected in parallel to a resistor element introduced into the main current path.

2. The circuit breaker according to claim 1, wherein the second drive unit is connected via a rectifier to the main current path.

3. The circuit breaker according to claim 1, wherein between the second drive unit and the main current path a Zener diode and/or a second switch is connected.

4. The circuit breaker according to claim 1, further comprising a control unit fed from the control circuit, via which the first drive unit is energized.

5. The circuit breaker according to claim 1, wherein the drive comprises a moving magnet actuator via which the two drive units are formed.

6. The circuit breaker according to claim 1, wherein the resistor element comprises an additional switch, which is controlled via an additional control unit.

7. The circuit breaker according to claim 1, wherein, parallel to the mechanical switch, a fuse is connected.

8. The circuit breaker according to claim 1, wherein a semiconductor switch is connected in parallel to the mechanical switch or to the series connection from the mechanical switch and the resistor element.

9. The circuit breaker according to claim 1, wherein the mechanical switch comprises an arcing chamber comprising a plurality of flat arcing strips arranged in parallel to each other and stacked on top of each other in a stacking direction, which are made of a ceramic.

10. A motor vehicle with a high-voltage electrical system, and with a low-voltage electrical system and with a circuit breaker according to claim 1, wherein the control circuit is electrically connected to the low-voltage electrical system, and wherein the high-voltage electrical system has the main current path.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0075] FIG. 1 shows, schematically, a motor vehicle with a circuit breaker;

[0076] FIG. 2 shows a simplified circuit diagram of the circuit breaker, which comprises a “moving magnet actuator” with two drive units;

[0077] FIG. 3 shows schematically, the “moving magnet actuator” in a sectional representation;

[0078] FIGS. 4-6 show, according to FIG. 2, in each case an example embodiment of the circuit breaker; and

[0079] FIG. 7 shows, in perspective, an arcing chamber of the mechanical switch.

DETAILED DESCRIPTION

[0080] FIG. 1 shows a schematically simplified motor vehicle 2 in the form of a truck. The motor vehicle 2 has a plurality of wheels 4, via which contact is made to an unspecified roadway. At least one of the wheels 4 is driven via a main drive 6, which comprises one or more electric motors. In other words, the motor vehicle 2 is designed either as a hybrid motor vehicle or as an electric motor vehicle.

[0081] The main drive 6 is connected via a high-voltage electrical system 8 to a high-voltage battery 10. Via the high-voltage battery 10, the high-voltage electrical system 8 is thus fed and the main drive 6 is operated. The high-voltage battery 10 provides an electrical DC voltage between 400 V and 800 V, wherein the electric currents flowing between the high-voltage battery 10 and the main drive 6 may be several 10 A. Furthermore, the high-voltage electrical system 8 is connected to an unspecified charging port, so that the high-voltage battery 10 can be charged via the charging port and the high-voltage electrical system 8.

[0082] In the high-voltage electrical system 8, a circuit breaker 12 is incorporated, via which the high-voltage electrical system 8 is protected. It is possible to prevent an electrical current flow between the high-voltage battery 10 and the main drive 6 via the circuit breaker 12. The circuit breaker 12 trips in the event of a fault, so that in the event of a fault, for example in the event of damage to the main drive 6, further damage or uncontrolled behavior of the main drive 6 and also a danger to occupants or pedestrians is avoided. Further, the circuit breaker 12 is signally connected to an unspecified on-board computer, via which safe functions are carried out with the involvement of the circuit breaker 12 or requests to perform safety functions are transmitted to the circuit breaker 12, which are subsequently carried out at least partially thereto by means thereof. Consequently, the circuit breaker 12 also serves to provide functional safety.

[0083] The circuit breaker 12 is also electrically connected to a low-voltage electrical system 14, which is fed by a battery 16. Via the battery 16, a DC voltage of 24 V is provided during operation, and with the low-voltage electrical system 14, unspecified auxiliary units are energized, which serve the operation of the main drive 6 and/or the provision of comfort functions.

[0084] FIG. 2 shows a simplified switch diagram of the circuit breaker 12. The circuit breaker 12 has a main current path 18 extending between two connections 20. The two connections 20 are screw or plug connections and inserted into an unspecified housing of the circuit breaker 12, which is made of a plastic. The circuit breaker 12 further comprises a further main current path 22, which extends between two further connections 24, which are identical to the connections 20. The main current path 18 and the further main current path 22 form a part of the high-voltage electrical system 8, which thus has the main current path 18. For this purpose, the connections 20 and the further connections 24 are electrically contacted with corresponding cables or other wires of the high-voltage electrical system 8.

[0085] The further main current path 22 is created only via a busbar which is made of a metal, such as copper or brass. Via the further connections 24, the further main current path 22 is connected to ground, and in normal operation of the motor vehicle 2, the electric DC voltage provided via the high-voltage battery 10 is applied between the main current path 18 and the further main current path 22. In other words, the main current path 18 and the further main current path 22 are assigned to different poles of the high-voltage battery 10.

[0086] In the main current path 18, a mechanical switch 26 is introduced, via which the two connections 20 are connected, and which is designed as a double interrupter. For this purpose, the mechanical switch 26 comprises a fixed contact 28 and a further fixed contact 30, each of which is rigidly connected to one of the connections 20 via a rigid busbar and spaced from each other. The two fixed contacts 28, 30 are made of a material deviating from the material of the assigned busbars, which is in particular comparatively burn-proof.

[0087] The mechanical switch 26 further comprises a contact bridge 32 which is formed via a further busbar which is mounted to be longitudinally moving, i.e., movable, via an unspecified guide of the housing of the circuit breaker 12. At the opposite ends of the contact bridge 32, a moving contact 34 and a further moving contact 36 are connected, namely welded, wherein the material of the moving contacts 34, 36 corresponds to the material of the fixed contacts 28, 30.

[0088] By moving the contact bridge 32, it is possible to put the moving contact 34 in mechanically direct contact with the fixed contact 28 and the further moving contact 36 in mechanically direct contact with the further fixed contact 30, so that these are each electrically conductively connected. As a result, there is a low-impedance electrical connection between the two connections 20, and the mechanical switch 26 is electrically conductive. In other words, the mechanical switch 26 is closed. Furthermore, it is possible to distance the respective assigned contacts 28, 30, 34, 36 from each other by adjusting the contact bridge 32. In this case, the mechanical switch 26 is electrically non-conductive and thus open.

[0089] The contact bridge 32 is driven via a drive 38, so that when operating the drive 38, the contact bridge 32 is adjusted and thus the mechanical switch 26 is closed or opened. Consequently, the drive 38 is in active connection with the contact bridge 32, namely mechanically coupled to it. The drive 38 has a first drive unit 39, which is powered via a control unit 40. For this purpose, the control unit 40 is electrically connected to the drive 38, namely the first drive unit 39. For powering the control unit 40, and consequently the first drive unit 39, the control unit 40 is electrically contacted with a control circuit 42, via which a DC voltage is provided. The control circuit 42 is electrically directly contacted with the low-voltage electrical system 14, so that also via the control circuit 42, the DC voltage in the amount of 24 V is conducted. In summary, the first drive unit 39 is thus energized via the control circuit 42.

[0090] The control unit 40 comprises an energy storage 44 in the form of a capacitor, which is charged via the control circuit 42, and which is electrically connected in parallel to a microcontroller of the control unit 40. Thus, fluctuations in the electrical voltage and/or the electrical current of the low-voltage electrical system 14 are intercepted via the energy storage 44, so that damage to the microcontroller is thereby avoided. Also, it is possible due to the energy storage 44, in the event of a failure of the low-voltage electrical system 14, to actuate the drive at least once 38 and in this way open the switch 26.

[0091] In a more detailed variant, the control unit 40 also comprises a charge pump via which it is possible to increase the electrical voltage applied to the capacitor 44 as compared to the electric voltage provided via the low-voltage electrical system 14, so that the amount of energy stored via the energy storage 44 is increased. Thus, safe operation of the drive 38 is always possible, even if there is a complete failure of the low-voltage electrical system 14 or the drive 38 is slightly blocked.

[0092] Via the microcontroller, the current supply of the first drive unit 39 is adjusted, and this is signally connected to a current sensor 46 of the main current path 18. The current sensor 46 is inserted into the main current path 18 and designed as a shunt. Thus, via the current sensor 46, the electric current conducted via the main current path 18 can be measured. Furthermore, the circuit breaker 12 comprises a first voltage sensor 48, via which the electrical voltage applied between one of the connections 20 and one of the further connections 24 can be measured. Via a second voltage sensor 50, the electrical voltage applied between the remaining connection 20 and the remaining further connection 24 can be measured.

[0093] Via a third voltage sensor 52, the electrical voltage 51 decreasing through the series connection of the current sensor 46 and a resistor element 51 introduced between the current sensor 46 and the switch 26 in the main current path 18 is measurable, and via a fourth voltage sensor 54, the electrical voltage decreasing via the series connection from the current sensor 46, the resistor element 51 and the mechanical switch 26 is measurable. All voltage sensors 48, 50, 52, 54 are signally connected to the control unit 40, namely the microcontroller.

[0094] During operation, the temporal change of the electric voltages measured via the voltage sensors 48, 50 52, 54 and the electric current measured via the current sensor 46 is checked via the microcontroller of the control unit 40. If the temporal change of the measured current corresponds to an increase and exceeds a certain limit, the drive 38, namely the first drive unit 39, is controlled via the control unit 40, so that the switch 26 is opened. The limit value is chosen in such a way that it is only exceeded in the event of a fault, namely in the event of an electrical short circuit of the electric motor of the main drive 6. Due to the actuation of the mechanical switch 26, the electric current is interrupted and thus further destruction of the electric motor or other components of the main drive 6 is avoided. Likewise, the actuation of the mechanical switch 26 is carried out via the control unit 40, when the electrical voltage detected by the voltage sensors 48, 50, 52, 54 is used to conclude the fault, such as a malfunction of certain components of the motor vehicle 2.

[0095] Electrically parallel to the resistor element 51, which is electrically introduced between the further fixed contact 30 of the mechanical switch 26 and the current sensor 46 in the main current path 18, a second drive unit 56 of the drive 38 is connected. Here, the second drive unit 56 is electrically connected to the main current path 18 via a rectifier 58. Via the rectifier 58, which has an internal electrical resistance, it is ensured that the electric current carried by the second drive unit 56 flows only in a certain direction, regardless of the current flow direction of the main current path 18. Thus, the circuit breaker 12 is bidirectionally embodied, wherein the design of the second drive unit 56 is simplified. Between the rectifier 58 and the second drive unit 56, a Zener diode 60 is connected, wherein the blocking direction is arranged such that only starting from a minimum voltage provided via the rectifier 58 does the current supply of the second drive unit 56 occur.

[0096] The resistor element 51 is a PTC thermistor and has negligible ohmic resistance in normal operation. However, if the electric current conducted via the main current path 18 rises above a limit value, the temperature of the main current path 18 and thus also of the resistor element 51 increases due to electrical losses, hence the ohmic resistance of the resistor element 51 also increases. If the resistance is greater than the resistance of the parallel connected branch, which comprises the interconnection of the rectifier 58, the second drive train 56 and the Zener diode 60, the electric current commutates from the resistor element 51 to the parallel connected branch and thus also to the second drive unit 56, which is thus energized. As a result, a force is exerted via the second drive unit 56, which acts on the contact bridge 32, so that the moving contacts 34, 36 are distanced from the respective assigned fixed contacts 28, 30 and consequently the mechanical switch 26 is opened.

[0097] As a result, at a comparatively high electric current, the mechanical switch 26 is also opened via the second drive unit 56. In this case, it is possible to use both drive units 39, 56 to open the mechanical switch 26. In this case, a comparatively large force is applied to the contact bridge 32, hence the switching time is shortened and thus the mechanical switch 26 is opened in a comparatively short period of time. Consequently, the current flow between the two connections 20 is prevented within the comparatively short period of time. Furthermore, redundancy is given in this way, hence security is increased.

[0098] However, it is also possible to operate each of the drive units 39, 56 separately from each other. In this case, the force acting on the contact bridge 32 is reduced, so that the mechanical load is also reduced. It is also possible to energize the first drive unit 39 due to the control unit 40 in case of faults where, for example, no overcurrent occurs, or in which the electrical voltage dropping through the resistor element 51 is not sufficient for the electric current to commutate to the second drive unit 56.

[0099] If the mechanical switch 26 is opened, and the fault is present, there is a comparatively high electrical voltage between the connections 20 during the opening of the switch 26. As a result, an arc forms between the fixed contacts 28, 30 and the respective assigned and moving contact 34, 36 moving away, through which a current flow continues to take place. However, the electrical voltage dropping through the mechanical switch 26 increases. As a result, the electrical current commutates from the electrical switch 26 to a fuse 56 connected in parallel. Thus, the electrical current flows between the two connections 20 through the fuse 62, hence the arcs extinguish.

[0100] The fuse 62 is dimensioned in such a way that it trips in the event of a fault. The threshold at which the fuse 62 trips lies between the value of the electric current in normal operation and the value of the electric current resulting from a short circuit, wherein the exact value of the threshold in between can be chosen arbitrarily without changing the functioning of the circuit breaker 12. Thus, fault tolerances for the fuse 62 can be selected to be comparatively large, hence manufacturing costs are reduced. After tripping the fuse 62, no electric current is carried via this, and the two connections 20 are galvanically isolated from each other.

[0101] FIG. 3 schematically shows the drive 38 in a sectional representation along an axis 64. The drive 38 is designed as a “moving magnet actuator” and thus comprises two disc coil or drum-like holders 66 arranged concentrically to the axis 64 and spaced along it, which are made of a ferromagnetic material. Between these, a ring-shaped short-circuit sheet 68 is positioned concentrically to the axis 64, which is also made of a ferromagnetic material. Via the holders 66 and the short-circuit sheet 68, a hollow cylinder is thus formed, within which another holder 70 is arranged from a plastic and is movably mounted via an unspecified guide along the axis 64. A rod 72 extending along the axis 64, which is attached to the contact bridge 32, either directly or via an unspecified mechanism, is attached to the holder 70. In the cylindrical further holder 70, a cylindrical permanent magnet 74 is embedded, which comprises two magnetic poles 76, each of which forms one of the ends of the permanent magnet 74 in a direction parallel to the axis 64.

[0102] The first drive unit 39 of the drive 38 comprises two electric coils 78. Each of the electric coils 78, which are identical to each other, is wound on one of the holders 66, and these are electrically connected in parallel to each other. The second drive unit 56 comprises two further electric coils 80, one of which is wound onto one of the electric coils 78 and the other on the remaining electric coils 78. The two other electric coils 80 are also electrically connected in parallel to each other. The number of turns of the further electric coils 80 is less than the number of turns of the electric coils 78.

[0103] If the two drive units 39, 56 are not energized, the permanent magnet 74 is pulled into a position substantially within the short-circuit sheet 68 due to the magnetic interaction with the short-circuit sheet 68 and the holders 66, wherein a force of about 30 N acts on the permanent magnet 70 and thus also on the further holder 70. With this force, the short-circuit bridge 32 is thus held in the desired position, namely in the one in which the mechanical switch 26 is closed.

[0104] In the event of a fault, the first drive unit 39 is energized via the control unit 40, so that a magnetic field is created via the electric coils 78, which interacts with the magnetic field of the permanent magnet 74. The second drive unit 56 and thus also the further electric coils 80 are also energized. Via this, the magnetic fields created by the electric coils 78 are amplified. Due to the magnetic fields created, the permanent magnet 74 is pushed away from one of the holders 66 along the axis 64 and pulled to the remaining holder 66. In this case, comparatively large forces act on the permanent magnet 74, and consequently through the further holder 70 and the rod 72 also on the contact bridge 32, so that the mechanical switch 26 is opened comparatively quickly.

[0105] If there is no fault case, and, for example, only the current supply of the main drive 6 is to be interrupted, for example for maintenance, the first drive unit 39 is energized via the control unit 40. Since there is no overcurrent, the electric current does not commutate from the resistor element 51 to the second drive unit 56, whose further electrical coils 80 are thus not energized. Consequently, a reduced force acts on the contact bridge 32, and the switch 26 is opened comparatively slowly. As a result, the electrical and also mechanical load of the circuit breaker 12 is reduced. Since in this case, the applied electrical voltage is limited between the connections 20, the fuse 62 does not trip, and the circuit breaker 12 can, for example, after completion of maintenance, be put back into the electrically conductive state. For this purpose, for example, the first drive unit 39 is energized in the opposite direction or the current supply is terminated, so that the permanent magnet 74 is again pulled to the short-circuit sheet 68.

[0106] FIG. 4 shows an alternative embodiment of the circuit breaker 12 schematically simplified, wherein some components, such as the main current path 22 and the voltage sensors 48, 50, 52, 54, are not shown. However, these are also present, but can also, as in the previous embodiment, be omitted. The fuse 62 is omitted in this embodiment, but also present in an unspecified variant. The first drive unit 39 and the control unit 40 are not shown, but are not modified, just like the mechanical switch 26 shown.

[0107] In the variant shown herein, the rectifier 58 is electrically connected in parallel to the series connection from the current sensor 46 and the resistor element 51. However, the different arrangement of the current sensor 46 shown in FIG. 2 is also possible here.

[0108] The second drive unit 56 is not modified, but the Zener diode 60 is replaced by a second switch 82, which is controlled by a second control unit 84. The second switch 82 is a semiconductor switch, and electrically connected between the rectifier 58 and a second current sensor 86, which is electrically connected between the second switch 82 and the second drive unit 56. The second current sensor 86 is used to measure the electrical current conducted to the second drive unit 56 and carried by it and is signally connected to the second control unit 84.

[0109] The current of the second control unit 84 is supplied via a second power supply 88, which is electrically contacted with the outputs of the rectifier 58 facing the second drive unit 56. Consequently, the second power supply 88 and thus also the second control unit 84 is only energized if the electrical voltage dropping through the resistor element 51 is greater than that of the branch connected in parallel. The second switch 82 is closed by the second control unit 84 as soon as this is energized, so that the second drive unit 56 is energized and consequently the mechanical switch 26 is opened. However, if the overcurrent is comparatively large and could lead to the destruction of the second drive unit 56, the second switch 82 is opened via the second control unit 84 and thus the current supply of the second drive unit 56 is terminated. The determination of the excessive overcurrent is carried out on the basis of the electric current measured via the second current sensor 56. In addition, it is possible via the second switch 82 to apply a pulse width modulated voltage to the second drive unit 56, so that the force exerted by the second drive unit 56 on the contact bridge 32 is limited.

[0110] The rectifier 58 has a total of 4 diodes 90, and is thus passively designed. Thus, no control unit or the like is required for the operation of the rectifier 58, so that robustness is increased. The resistor element 51 is formed via two additional switches 92, each of which are semiconductor switches which are interconnected antiserially. The additional switches 92 are controlled via an additional control unit 94, which is powered via the control circuit 42.

[0111] The additional control unit 94 is signally connected to the current sensor 46. If the overcurrent is measured via the current sensor 46, this is evaluated via the additional control unit 94, and the additional switches 92 are controlled in such a way that they open, i.e., electrically lock. Due to the anti-serial interconnection of the two additional switches 92, it is possible to interrupt the current flow in both directions via the main current path 18.

[0112] After opening the further switches 92, the resistor element 51 substantially abruptly has a comparatively high electrical resistance, and the electric current commutates to the second drive unit 56. In order to avoid an overvoltage at the rectifier 58 and the resistor element 51, a surge protector 96 is connected in parallel, which is a varistor in this variant. In an unspecified variant, the surge protector 96 is realized via Zener diodes, TVS diodes, an RCD circuit, a controllable resistive load or a combination thereof.

[0113] The additional control unit 94 is, as shown, signally connected to the second control unit 84, and via the additional control unit 94, the second control unit 84 is controlled such that the second switch 82 is closed when the additional switches 92 are opened. In an unspecified variant, the second control unit 84 is not present, and its functions are taken over via the additional control unit 94, via which thus the second switch 82 is controlled and the second current sensor 86 is read out. In a further variant, the signaling connection between the additional control unit 94 and the second control unit 84 is not present, and these are separate and independent of each other.

[0114] In the variant shown herein, a series connection formed of a second resistor element 98, an additional current sensor 100 and an additional fuse 102 is connected in parallel to the series connection from the current sensor 46 and the resistor element 51. However, an embodiment of the circuit breaker 12 without these series connections and consequently without the second resistor element 98 is possible.

[0115] The second resistor element 98 is formed via two additional switches 104, each of which is designed as semiconductor switches. In this case, the two semiconductor switches 104 are connected antiserially to each other, so that an electrical current flow in both directions can be interrupted via this. The two additional switches 104 are operated via a second additional control unit 106, which is powered by a second additional power supply 108. The second additional power supply 108 is operated by the electrical voltage dropping through the second resistor element 98. Parallel to the second resistor element 98, a second surge protector 110 is connected, which is also a varistor in the variant shown. However, all variants possible for surge protector 96 can also be used here. In an embodiment not specified in more detail, the operation of the second surge protector 110, namely the limitation of the electrical voltage applied to the second resistor element 98, is also perceived via the surge protector 96.

[0116] In the illustrated variant of the circuit breaker 12, the additional switches 92 have a comparatively low internal resistance, so that in normal operation via these, the electric current conducted via the main current path 18 is conducted. In this case, the electrical voltage dropping through the second resistor element 98 is comparatively low, hence the second additional power supply 108, and therefore also not the additional control unit 106, is operated. As a result, the second additional switches 104 are open. If the fault occurs, the additional switches 92 are first actuated via the additional control unit 94. The resulting increased electrical voltage dropping at the second resistor element 98 leads to the operation of the second additional power supply 108 and therefore also to the current supply of the additional control unit 106, via which the second additional switches 104 are closed. Thus, the electric current commutates to the second resistor element 98, i.e., the second additional switches 104. As a result, the maximum electrical voltage applied to the resistor element 51 is limited, and via the additional switches 92 only a comparatively low electrical voltage is switched, so that semiconductors can be used comparatively inexpensively for the additional switches 92.

[0117] Only after the additional switches 92 are current blocking are the second additional switches 104 opened, whose switching capability is increased as compared to that of the additional switches 92. In other words, switching an increased electrical voltage via the second additional switches 104 is possible without destroying these. Subsequently, the electric current flows via the second drive unit 56 and optionally via the surge protectors 96, 110, and subsequently the mechanical switch 26 is opened.

[0118] As long as the second additional switches 104 are current carrying, the electrical current carried therewith is measured via the additional current sensor 100. If the electric current exceeds a corresponding limit that could lead to the destruction of the second additional switches 104, they are opened via the additional control unit 106 and thus the current flow is interrupted. The additional fuse 102 serves as redundancy for this, in particular in case of malfunction of the additional control unit 106.

[0119] FIG. 5 shows a further variant of the circuit breaker 12, wherein as compared to the preceding embodiment, the series connection having the second resistor element 98, the additional current sensor 100 and the additional fuse 102 is replaced by a choke 112. Via this, the temporal change of the electric current conducted via the second drive unit 56, the surge protector 96 and/or the resistor element 51 is limited when the mechanical switch 26 is actuated, i.e., the current flow through the main current path 18 is created or terminated. Thus, a load on these components is reduced. It is thus possible to use comparatively cost-effective components. However, the general mode of operation of the second drive unit 56, the rectifier 58, the resistor element 51 and the additional control unit 94 and the second control unit 84 and their corresponding circuits are not changed.

[0120] The mechanical switch 26 is bridged in this variant via a series connection from a switch group 114, a third current sensor 116 and a third fuse 118. The switch group 114 comprises two semiconductor switches 120 antiserially connected to each other. Consequently, the two semiconductor switches 120 are connected in parallel to the mechanical switch 26. The two semiconductor switches 120 are operated via a further control unit 122 and set via this either to the electrically conductive or electrically non-conductive state. The current supply of the further control unit 122 is carried out via a further power supply 124, which is supplied either via an electrical voltage dropping through the mechanical switch 26 or via the control circuit 42.

[0121] Parallel to the switch group 114, a further surge protector 126 is connected, which is a varistor in the variant shown. In an unspecified variant, the further surge protector 126 is realized via Zener diodes, TVS diodes, an RCD circuit, a controllable resistive load or a combination thereof. Via the further surge protector 126, an electrical overvoltage at the switch group 114 and the further control unit 122 and the further power supply 124 is avoided, which could otherwise lead to destruction thereof.

[0122] In summary, the structure of the further surge protector 126, the switch group 114, the further control unit 122, the further power supply 124, the third current sensor 116 and the third fuse 118 corresponds to the structure of the second surge protector 110, the second resistor element 98, the second additional control unit 106, the second additional power supply 108, the additional current sensor 102 and the additional fuse 102.

[0123] In this embodiment of the circuit breaker 12, the semiconductor switches 120 are electrically non-conductive as long as the mechanical switch 26 is closed. When the switch 26 is opened, the electrical voltage applied through the switch group 114 increases, so that the further power supply 124 is operated and therefore the further control unit 122 is energized. Via the further control unit 122, the switch group 114, namely the individual semiconductor switches 120, is controlled, so that these are current conducting. As a result, the electric current commutates and is guided via the switch group 114. Therefore, the arcs formed between the fixed contacts 28, 30 and the respective moving contacts 34, 36 extinguish. Subsequently, the semiconductor switches 120 are electrically controlled in such a way that they block electrical current, so that the electrical current flow between the two connections 20 is terminated.

[0124] Via the further surge protector 126 it is ensured until then that no overload of the semiconductor switches 120 occurs. If it is detected via the further current sensor 116, which is signally connected to the further control unit 122, that a comparatively large electric current is conducted with the switch group 114, which could lead to damage to the semiconductor switches 120, the semiconductor switches 120 are also opened and thus damage to the switch group 114 is avoided. Via the further fuse 118 it is ensured that even in the event of a malfunction of the further control unit 122 and a comparatively high electric current, the current flow via the switch group 114 is interrupted.

[0125] In this variant of the circuit breaker 12, there is a plurality of different sequences of control of the individual components so that the circuit breaker 12 is opened. Thus, it is possible that first the switch group 114 is current carrying and then the mechanical switch 26 is opened. Subsequently, the switch group 114 is converted to the electrically non-conductive state. In this way, a low-arc switching is carried out via the circuit breaker 12. However, it is also possible to first actuate the mechanical switch 26 so that the further control unit 122 is energized based on the electrical voltage generated by the mechanical switch 26. Subsequently, the switch group 114 is set to the electrically conductive state, so that the arcs extinguish. Subsequently, the switch group 114 is also converted to the electrically non-conductive state. In a further type of control, the switch group 114 is first set to the electrically conductive state and then the resistor element 51 to the electrically non-conductive state. Consequently, the mechanical switch 26 is opened. Subsequently, the switch group 114 is put into the electrically non-conductive state, wherein during this time or until then, the current rise is limited via the choke 112.

[0126] In an unspecified further development, the circuit breaker 12 is constructed according to FIG. 5. However, the bridging of the mechanical switch 26 is omitted. In other words, the switch group 114, the further control unit 122, the further power supply 124, the further surge protector 126 and the third current sensor 116 and the third fuse 118 are not present.

[0127] FIG. 6 shows a further embodiment of the circuit breaker 12. Compared to the preceding embodiment, not only the mechanical switch 26, but the series connection having the mechanical switch 26 and the resistor element 51 and the current sensor 46 is bridged via the series connection from the switch group 114, the third current sensor 116 and the third fuse 118. In addition, the choke 112 is omitted, although it may also be present here. Compared to the variant shown in FIG. 4, the additional fuse 102 is guided on the opposite side of the mechanical switch 28 against the main current path 18, so that the series connection of the second resistor element 98, the additional current sensor 100 and the additional fuse 102 bridges the series connection having the current sensor 46, the resistor element 51 and the mechanical switch 26. With this variant it is also possible that the choke 112 is present.

[0128] In the case of an overcurrent, the resistor element 51 is controlled via the additional control unit 94, so that it is no longer current bearing. As a result, the electric current commutates to the second drive unit 56, which has an electrical resistance. Therefore, the electrical voltage dropping through the second resistor element 98 or the switch group 114 increases, so that the second additional power supply 108 or the further power supply 124 are operated. Via the now energized second additional control unit 106 or further control unit 122, the second resistor element 98 or the switch group 114 is put into the electrically conductive state.

[0129] Due to the continuous current supply of the second drive unit 56, the mechanical switch 26 is opened. As a result, the electric current between the connections 20 is subsequently conducted only via the second resistor element 98 or the switch group 114. Via any existing choke 112, the current increase through this branch is limited, so that overloading is avoided. Subsequently, via the second additional control unit 106 or the further control unit 122, the second resistor element 98 or the switch group 114 is set to the electrically non-conductive state, so that the electrical current flow between the two connections 20 is terminated. In this variant, there is no formation of an arc via the mechanical switch 26.

[0130] FIG. 7 shows an arcing chamber 128 of the mechanical switch 26 in perspective. The arcing chamber 128 is used here to extinguish an arc arising during a switching operation of the mechanical switch 26 unless the other existing components are used for this purpose. The arcing chamber 128 comprises a plurality of arcing strips 132 stacked on top of each other in a stacking direction 130. The arcing strips 132 are made of an aluminum-oxide ceramic and designed flat and arranged perpendicular to the stacking direction 130. The thickness of the arcing strips 132, i.e., their expansion in the stacking direction 130, is between 1 mm and 2 mm. The arcing strips 132 lie directly next to each other, so that a stack 134 is formed. The stack 134 has a plurality of layers 136 arranged on top of each other in the stacking direction 130, which are thus arranged perpendicular to the stacking direction 130.

[0131] Each of the layers 136 are assigned two of the arcing strips 132. The two arcing strips 132 of each layer 136 are different from each other, and one of the arcing strips 132 is wedge-shaped and the remaining one trapezoidal. In other words, the arcing strips 132 assigned to each of the layers 136 differ, but each layer 136 is assigned the same arcing strips 132, i.e., the same type. In other words, the arcing chamber 128 has two different types of arcing strips 132, namely the wedge-shaped and the trapezoidal, and these are evenly divided among the layers 136.

[0132] The two arcing strips 132 of each layer 136 are spaced to each other perpendicular to the stacking direction 130, so that between them a slot 138 is formed. Four of the layers 136 are each combined into a group 140, wherein the arcing strips 132 of each group 140 are arranged flush with each other. The arcing strips 132 of the respective adjacent group 140, on the other hand, are arranged mirror-inverted, so that the stack 134 has a plurality of superimposed chambers 142 that are separated from each other in the stacking direction 130, each of which is formed via the aligning slots 138. Due to the wedge or trapezoidal shape, a notch 144 is formed in each of the layers 136, which merge into the respective chambers 142. There are a total of four such groups 140.

[0133] The stack 134 is enclosed on both sides via a holder 146 and thus stabilized. The holders 146 are mirror image to each other and made of a plastic and each have a foot 148. The two holders 146 are attached to each other at the respective foot 148, so that the stack 134 is held by a force fit between the two holders 146 both in the stacking direction 130 and perpendicular to it. On the side opposite the stack 134, each of the holders 146 has a rectangular pot or pan-shaped receptacle 150, within which a permanent magnet 152 is inserted in the assembly state, each of which forms a driving element.

[0134] The arcing chamber 128 is oriented with respect to the fixed contact 28, 30 and the moving contact 34, 36 such that an arc arising when actuating the mechanical switch 26, i.e., when the drive 38 is actuated, meets the stack 134 in the region of the notches 144. Due to the interaction between the magnetic field of the permanent magnets 152 and the magnetic field created by the arc, this is driven further into the stack 134, namely into the individual chambers 142. Thus, embedded sections of the arc are formed in the respective chambers 142, which are designed in a U-shape. The subsections are connected to each other, wherein the connecting sections enclose the stack 134 on the side of the notches 144. Consequently, the arc is comparatively long. Due to the notches 144, the arc is not able to bypass the arcing chamber 128. Because of the increase in the length of the arc, the electrical voltage required to maintain it increases.

[0135] Furthermore, there is heat input from the plasma forming the arc into the individual arcing strips 132, so that the arc is cooled. Due to the ceramic used, the heat is dissipated comparatively effectively and the arc is thus cooled. Because of the cooling, the electrical voltage required to maintain the arc also increases. Since the individual arcing strips 132 are separate from each other, no excessive mechanical stress forms in the stack 134 even with uneven heating of the individual arcing strips 132, which could lead to destruction.

[0136] If the choke 112 is present, as for example in the embodiment shown in FIG. 5 and in the unspecified modification described therein or in the not-shown further development of the further embodiment of FIG. 6, this is also used in a further development to drive the arc into the chambers 142. Here, the choke 112 is positioned accordingly and thus acts as a so-called blowout coil. Thus, it is possible that the permanent magnets 152 are omitted, or these are available as additional support. The choke 112 is live only when the mechanical switch 26 is actuated. Thus, the magnetic field for driving the arc into the chambers 142 is generated only if the arc is actually present or at least could arise.

[0137] The invention is not limited to the embodiments described above. Rather, other variants of the invention can be derived from it by the skilled person without leaving the subject-matter of the invention. In particular, all the individual features described in connection with the individual embodiments can also be combined in other ways without departing from the subject-matter of the invention.

[0138] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.