Switchgear and voltage limiting device having the switchgear

Abstract

The present invention relates to a switching device, in particular a switching device for a voltage limiting device, which has a first fixed switching contact (14) electrically connected to a first device connection end (8), a second fixed switching contact (15) electrically connected to a second device connection end (9), and a movable switching contact (16). Furthermore, the present invention also relates to a voltage limiting device having such a switching device (5). The first and second fixed switching contacts (14, 15) of the switching device are arranged side by side such that their contact surfaces (14A, 15A) face the same direction. The movable switching contact (16) can be moved between a closed position and an open position. In the closed position, the first and second fixed switching contacts (14, 15) are electrically connected to each other, and in the open position, the first and second fixed switching contacts (14, 15) are separated from each other. The first and second fixed switching contacts (14, 15) and the movable switching contact (16) form an arrangement of electrical conductors that are arranged substantially parallel to each other. At least one of the fixed switching contacts (14, 15) has an elongated contact surface extending in the current flow direction A. Electrodynamic forces act on the fixed conductors (14, 15) and the movable conductor (16), and the direction of these electrodynamic forces is such that the conductors attract each other, i.e., the switching contacts tend to close.

Description

Field of the Invention

[0001] The present invention relates to a switching device, in particular a switching device for a voltage limiting device, having a first fixed switching contact electrically connected to a first device connection end, a second fixed switching contact electrically connected to a second device connection end, and a movable switching contact, wherein the movable switching contact moves between a closed position and an open position, in which closed position the first and second fixed switching contacts are electrically connected to each other, and in which open position the first and second fixed switching contacts are separated from each other. Furthermore, the present invention also relates to a voltage limiting device having such a switching device. Background Art

[0002] Voltage limiting devices (VLDs) are used in the field of rail power supply, in particular in the field of rails driven by direct current. In the case of rails driven by direct current, the running rail is generally used as the return conductor for the running current, wherein the running rail is insulated from the ground to prevent the occurrence of stray currents. The return current flowing through the running rail causes a potential difference relative to the ground due to the resistance of the rail, which can be measured as the voltage between the rail and the ground. In order to avoid inadmissible touch voltages that may occur during operation or in the event of a fault, voltage limiting devices are provided. A voltage limiting device is a self-resetting earthing short-circuit breaker, which is generally installed between the running rail and the earthing device and responds at a threshold value of the defined touch voltage.

[0003] Known voltage limiting devices have a switching device that establishes an electrical connection between two cable connection ends. Depending on the construction, the switching device has a single-pole or multi-pole switching contactor, which has fixed or movable switching contacts that are driven by an actuating unit. The switching device can also include thyratrons connected in parallel.

[0004] For known switching contactors, the contact surfaces of the fixed switching contact and the movable switching contact generally face each other. Immovable conductors connect the fixed switching contact to the first device connection end, while movable conductors connect the movable switching contact to the second device connection end. In these arrangements of switching contacts and conductors designed for frequent switching, electrodynamic forces occur, which act on the switching contacts. The direction of these forces is such that the switching contacts tend to open.

[0005] In certain application cases, the switching contactor must be able to switch very frequently and / or very quickly, and must also be able to switch on large currents and conduct for a certain period of time. If the current intensity is too high, technical measures must be taken to prevent the contactor from being damaged when switched on.

[0006] For a voltage limiting device, a known technical measure consists in operating a switching contactor together with a thyristor triggered according to the switching of the contactor. The thyristor can be switched within a few microseconds, while the contactor has a closing time that may be between 100 and 200 milliseconds. After the thyristor is triggered, the contactor can take over the load. To control the switching contactor or the thyristor, a control device is provided. All components are usually located in a control cabinet. Summary of the Invention

[0007] Accordingly, an object of the present invention is to implement a switching device that can allow a large switching capacity and conduct a large current for a short time when switched on. Another object of the present invention is to provide a voltage limiting device that allows a higher switching capacity and conducts a large current for a short time when switched on.

[0008] According to the present invention, this object is achieved by the features of the independent claims. The content of the dependent claims relates to advantageous embodiments of the present invention.

[0009] The switching device according to the present invention is characterized by a special arrangement and construction of the switching contacts, which, in the case of a large current flowing through, causes the emergence of an electrodynamic force that is directed such that the switching contacts attract each other.

[0010] The switching device according to the present invention has first and second fixed switching contacts and a movable switching contact. When a switching contact is mentioned hereinafter, especially a first and second switching contact, it is not to be understood that there must be only one switching contact provided, but rather the switching device according to the present invention can also have multiple fixed or movable switching contacts. For example, the switching device can include multiple components, each having a first and second fixed switching contact and a movable switching contact. These components can be operated individually to switch multiple currents, or these components can be connected in parallel.

[0011] The first and second fixed switching contacts are arranged such that their contact surfaces face the same direction. The movable switching contact can move between a closed position and an open position. In the closed position, the first and second fixed switching contacts are electrically connected to each other, and in the open position, the first and second fixed switching contacts are separated from each other. The first and second fixed switching contacts and the movable switching contact form an arrangement of electrical conductors that are substantially parallel to each other.

[0012] In this arrangement of the switch contacts, it is particularly important that the contact surface of at least one of the fixed switch contacts is an elongated contact surface extending in the current flow direction. Preferably, the contact surfaces of the two fixed switch contacts are elongated contact surfaces. In this sense, an elongated contact surface is understood to be a contact surface having a length in the current flow direction, which length is in any case greater than the width of the contact surface. The contact surface should be as long as possible in terms of its width. The current flow direction is defined as the direction in which the current flows from one fixed switch contact through the movable switch contact to the other fixed switch contact. Thus, the arrangement of the switch contacts forms an elongated conductor arrangement.

[0013] The switching device is thus constructed or can be operated in such a way that currents flowing in the same direction flow through the fixed switch contacts and the movable switch contacts in contact with the fixed switch contacts. The current flow causes an electrodynamic force to act on the fixed and movable conductors, which force is oriented such that the conductors attract each other, i.e., the switch contacts tend to close. It has been shown that the opening force acting on the conductive parts of the switching device, in particular its switch contacts, is thereby reduced and the load on the switch contacts is alleviated. Thereby, the electrical characteristics of the switching device are improved. The switching device can switch high loads without having to strengthen the contacts of the switching device or take other technical measures. This effect is enhanced as the length of the contact surface increases.

[0014] The particular arrangement and configuration of the switch contacts of the switching device according to the invention differ from the arrangement and configuration of the switch contacts of switching devices commonly available on the market, the switch contacts or contact surfaces of which are usually point-like, square or rectangular, with the rectangular contacts being wide and short in the current flow direction.

[0015] The first and second fixed switch contacts and the movable switch contact can in principle be constructed arbitrarily, i.e., have any cross-section and any length, as long as the switch contacts form a conductor arrangement through which currents flowing in the same direction flow, the conductors being substantially parallel and attracting each other. The strength of the electrodynamic force depends on the current intensity.

[0016] According to a preferred embodiment of the switching device, the first and second fixed switch contacts are linear electrical conductors, which preferably have a rectangular cross-section. However, the switch contacts can also have, for example, an oval or circular cross-section. In the case of a rectangular cross-section, it is advantageous that the first and second fixed switch contacts are arranged such that their wide sides form the contact surfaces. The fixed switch contacts are thus preferably short flat guide rails. The movable switch contact is likewise preferably a linear electrical conductor having a rectangular cross-section, the wide side of which preferably forms the contact surface. Thus, the switch contacts face each other with their wide sides.

[0017] Among them, relative to the current flow direction, the region where the movable switch contact and the fixed switch contact are arranged opposite to each other should be as long as possible, resulting in a larger electrodynamic force. In particular, this is achieved when the length of the movable switch contact is greater than or equal to the sum of the lengths of the first and second fixed switch contacts and the distance between the first and second fixed switch contacts. Thus, the movable switch contact extends over the entire available length of the fixed contact.

[0018] In another preferred embodiment, the movable switch contact can pivot between a closed position and an open position about an axis extending parallel to the longitudinal axes of the first and second fixed switch contacts. However, the movable switch contact can also perform a movement different from the rotational movement, such as a linear movement.

[0019] The actuation of the movable switch contact can be carried out by an actuation unit which can be constructed differently. The actuation unit can be, for example, an electromagnetic actuation unit.

[0020] The voltage limiting device according to the invention has a switching device according to the invention, by means of which an electrical connection can be established between a first cable connection end and a second cable connection end. A first electrical conductor electrically connects the first cable connection end to the first device connection end (connection end face) of the switching device, and a second electrical conductor electrically connects the second cable connection end to the second device connection end (connection end face). The two electrical conductors can each have a plurality of conductive parts. Other electrical components can also be provided in the respective current paths. The voltage limiting device is characterized in that a conductor section of the first or second electrical conductor is arranged in a region in front of the movable switch contact at a distance as small as possible relative to the movable switch contact in a substantially parallel orientation, such that the movable switch contact moves away from the conductor section when moving from the open position to the closed position. The voltage limiting device is thus constructed or can thus be operated in such a way that the movable switch contact and the conductor section of the first or second conductor form an arrangement of parallel conductors through which currents flow in opposite directions. The current flow causes an electrodynamic force to act on the movable switch contact and the fixed conductor (current rail), and the force is oriented such that the conductors repel each other. Since the conductor section of the first conductor or the conductor in front of the movable conductor is arranged such that the movable switch contact moves away from the conductor section when moving from the open position to the closed position, the switch contact tends to close. It has been shown that thereby the force that the switching device has to exert to close the switch contact is reduced and the load on the conductive part (switch contact) is alleviated. Thus, the electrical characteristics of the voltage limiting device are improved. The voltage limiting device can switch high loads without having to strengthen the conductive part or take other technical measures. This effect also enhances the effect brought about by the special arrangement of the fixed conductor and the movable conductor described above.

[0021] In a preferred embodiment, in the closed position, the conductor section of the first or second electrical conductor that is substantially parallel to the movable switch contact and is in front of the movable switch contact and the movable switch contact are in one plane. However, the conductor section of the first or second conductor and the movable switch contact do not have to be precisely aligned with each other, that is, the conductors can also be in planes that are slightly offset from each other.

[0022] The conductor section of the electrical conductor that is substantially parallel to the movable switch contact and is in front of the movable switch contact can in principle be constructed arbitrarily, that is, have any cross-section and any length, as long as the conductor section and the movable switch contact form a parallel conductor arrangement through which currents in opposite directions flow, and the conductors repel each other. The strength of the electrodynamic force depends on the current intensity, and the size of the conductors also depends on the current intensity.

[0023] In a preferred embodiment, the conductor section of the first or second electrical conductor that is substantially parallel to the movable switch contact and is in front of the movable switch contact is a straight conductor section, which preferably has a rectangular cross-section. The conductor section is preferably arranged such that its wide side faces the movable switch contact.

[0024] The direction of the current flow through the first or second conductor depends on the potential applied at the first or second cable connection end, that is, whether the first or second cable connection end is at ground potential, for example.

[0025] The conductor section of the first or second electrical conductor that is substantially parallel to the movable switch contact and is in front of the movable switch contact has a first end portion facing the first fixed switch contact and a second end portion facing the second fixed switch contact.

[0026] According to one embodiment, the first electrical conductor has a conductor section that extends from the first cable connection end to the second end portion of the conductor section of the first electrical conductor that is substantially parallel to the movable switch contact and is in front of the movable switch contact, and the first electrical conductor has a conductor section that extends from the first end portion of the conductor section of the first electrical conductor that is substantially parallel to the movable switch contact and is in front of the movable switch contact to the first device connection end of the switching device. In this embodiment, the second electrical conductor extends from the second device connection end to the second cable connection end.

[0027] In an alternative embodiment, the first electrical conductor extends from the first cable connection end to the first device connection end. The second electrical conductor has a conductor section that extends from the second device connection end to a second end portion of the conductor section of the second electrical conductor that is oriented substantially parallel to the movable switch contact and before the movable switch contact, and the second electrical conductor has a conductor section that extends from a first end portion of the conductor section of the second electrical conductor that is oriented substantially parallel to the movable switch contact and before the movable switch contact to the second cable connection end.

[0028] In both embodiments, the conductor sections of the first or second conductor and the movable switch contact are flowed through by currents in different directions.

[0029] However, in addition to the above embodiments, other embodiments are also possible, in which the first and second conductors are connected such that current flows from the second fixed switch contact through the movable switch contact to the first fixed switch contact.

[0030] The voltage limiting device can be arranged in a conventional control cabinet, which can have a front and a back, a left side and a right side, and a top cover part and a bottom. The control cabinet can also accommodate components known in the prior art of the voltage limiting device, such as a control unit for the actuating unit.

[0031] The switching device according to the invention can be not only a DC switching device but also an AC switching device, wherein the above effects occur respectively during the positive or negative half-wave of the AC voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The advantageous embodiments of the present invention will be explained below with reference to the drawings. Among them:

[0033] Figure 1 A rail vehicle and a voltage limiting device are shown in a highly simplified schematic diagram.

[0034] Figure 2 A highly simplified schematic diagram shows the main components of a voltage limiting device having a switching device according to the present invention.

[0035] Figure 3 A control cabinet having a voltage limiting device is shown.

[0036] Figure 4 An embodiment of a switching device having fixed switch contacts, movable switch contacts, and an actuating unit is shown in a top view.

[0037] Figure 5 Shows along Figure 4 A cross-sectional view taken along line A-A.

[0038] Figure 6The arrangement of the fixed switch contacts and the movable switch contacts of the switching device and the conductors leading to the device connection terminals of the switching device is shown schematically.

[0039] Figure 7 An alternative embodiment of the arrangement of the fixed switch contacts and the movable switch contacts of the switching device and the conductors leading to the device connection terminals of the switching device is shown schematically.

[0040] Figure 8 A highly simplified schematic diagram of the switch contacts is shown. Detailed description of the specific implementation

[0041] Figure 1 A DC-driven rail vehicle and a voltage limiting device are shown. The rail vehicle 1 has wheels 1A that run on the running track 2. The running track 2 of the railway system is insulated from the ground 3. The resistance of the running track 2 causes a potential difference to occur between the rail vehicle 1 or the track 2 and the ground 3. The voltage limiting device 4 prevents an unacceptable contact voltage from occurring during normal track operation or during a fault condition (short circuit). The voltage limiting device 4 is installed between the running track 2 and the grounding facility and establishes an electrical connection (ground fault circuit interrupter) between the running track 2 and the ground 3.

[0042] Figure 2 The components of the voltage limiting device 4 that are important for the present invention are shown in a highly simplified schematic diagram. The voltage limiting device 4 has a switching device 5 according to the present invention for establishing an electrical connection between one or more cables 6 and one or more cables 7, where the cable 6 leads to components of a component group of an unshown part or a railway power supply facility (e.g., a rail), and the cable 7 can be connected to an unshown grounding facility or another rail. In this embodiment, the switching device is a DC switching device.

[0043] The switching device 5 according to the present invention has a first device connection terminal 8 and a second device connection terminal 9. The first device connection terminal 8 is electrically connected to the first cable connection terminal 11 through the first electrical conductor 10, and the second device connection terminal 9 is electrically connected to the second cable connection terminal 13 through the second electrical conductor 12. One or more cables 6, such as those leading to the rail, can be connected to the first cable connection terminal 11, and one or more cables 7, such as those connected to the grounding facility, can be connected to the second cable connection terminal 13.

[0044] The switching device 5 can be constructed as a conventional switch contactor suitable for switching high DC currents. However, the switching device according to the present invention is distinguished from the conventional switch contactor by the special arrangement and construction of the switch contacts. The switching device 5 has two fixed switch contacts 14, 15 and a movable switch contact 16, the special arrangement of which will be described in detail below.

[0045] The switching device 5 has an electromagnetic actuating unit 17, which may include a coil and a magnetic armature in order to actuate a shaft 17A, by means of which the movable switch contact 16 is opened or closed. The switching device may also have other components, such as a so-called spark chimney (Funkenkamin), which belongs to the prior art.

[0046] Furthermore, the voltage limiting device 4 has an operating and control unit 18. The components of the voltage limiting device are located in a control cabinet.

[0047] Figure 3 A view of the control cabinet 19 is shown in a simplified perspective view. The control cabinet 19 has four vertical profile bars 20 in the Figure 3 orientation shown, to which the front part 21, the rear part 22, as well as the left side part 23, the right side part 24, the top part 25 and the bottom part 26 are connected. The front part 21 is a pivotable door, which is fixed at a side hinge 27 on the right side of the control cabinet 19.

[0048] The operating and control unit 18 is located in the upper half of the door of the control cabinet 19, so that the operating elements 18a are accessible from the outside. The switching device 5 is located inside the control cabinet 19. Figure 3 Only the switching device 5 is schematically shown in the. The first and second cable connection ends 11 and 13 are located in the lower half of the control cabinet 19. The conductors 10, 12 leading to the switching device 5 are only schematically shown.

[0049] The special arrangement and construction of the switch contacts are described in the following with reference to Figures 4 to 8 description. Figure 4 and 5 show in detail the components of the switching device that are important for the present invention, where Figure 5 is a cross-section taken along line A - A. Figure 6 and 7 are simplified schematic diagrams and Figure 8 is a schematic diagram. The parts corresponding to each other in Figures 4 to 8 have the same reference numerals as in Figure 2

[0050] ​In this embodiment, the switching device 5 has two fixed switching contacts 14, 15 and a movable switching contact 16. In this embodiment, the switching contacts 14 to 16 have a substantially rectangular cross-section. The fixed switching contacts 14, 15 are flat guide rails made of a conductive material such as copper, which are arranged at intervals from each other. The contact surfaces 14A, 15A located on the wide sides of the fixed switching contacts point in one direction. The movable switching contact 16 is also a flat guide rail made of a conductive material such as copper, which has a cross-section with a substantially rectangular shape. The contact surface 16A of the movable switching contact 16 is located on its wide side. The movable switching contact 16 is arranged relative to the first and second fixed switching contacts 14, 15 such that the contact surface 16A faces the contact surfaces 14A, 15A of the first and second fixed switching contacts 14, 15. The movable switching contact 16 has the same length as the sum of the lengths of the fixed switching contacts 14, 15 and the distance between the fixed switching contacts. The longitudinal axes 14B, 15B of the fixed switching contacts 14, 15 and the longitudinal axis 16B of the movable switching contact 16 are parallel. The switching contacts 14 to 16 are located in the same plane or at the same height.

[0051] In this embodiment, the switching device 5 is arranged in the control cabinet 19 such that the switching contacts 14 to 16 are located in a substantially horizontal plane 28 with respect to the control cabinet, that is, they are substantially at the same height in the control cabinet, where the fixed switching contacts 14, 15 face the rear part 22 of the control cabinet and the movable switching contact 16 faces the front part 21 of the control cabinet( Figure 3 ). However, the switching contacts can also be arranged in a vertical plane.

[0052] Figure 4 and 5 The fixed switching contacts 14, 15 arranged side by side and the movable switching contact 16 arranged in front of the fixed switching contacts in this view are shown in detail. The movable switching contact 16 can pivot about a horizontal axis 29 such that the movable switching contact can move between a closed position and an open position. In the closed position, the fixed switching contacts 14, 15 are electrically connected to each other, and in the open position, the first and second fixed switching contacts are separated from each other.

[0053] The movable switching contact 16 is driven by an actuating unit 17, which is arranged beside the switching contacts 14 to 16, for example, on the left side. A mechanical device 30 is located on the other side of the switching contacts in order to elastically pre-tension the movable switching contact 16 against the fixed switching contacts 14, 15. For the sake of clarity, the electrical connections leading to the device connection ends 8, 9 and parts of the mechanical device are not shown. Components for fastening the contacts can also be provided on the fixed switching contacts 14, 15, and these components can be an integral part of the contacts. The movable switching contact 16 is screwed, for example, by means of screws 31 to fastening elements not shown in detail, and these fastening elements are in turn connected to the shaft 17A of the actuating unit 17.

[0054] The first fixed switch contact 14 is connected to the first conductor 10 and the second fixed switch contact 15 is connected to the second conductor 12( Figure 2 and 6 ). In the present embodiment, the first and second conductors 10, 12 are flat guide rails made of a conductive material such as copper. The conductors 10, 12 are connected at the connection end faces 8, 9, which may be provided on the side of the fixed switch contacts 14, 15 opposite to the contact faces 14A, 15A. This region represents the device connection ends 8, 9 of the switching device 5.

[0055] It is assumed hereinafter that during operation of the switching device 5, current flows from the first cable connection end 11 to the second cable connection end 13. The longitudinal axes 14B, 15B of the fixed switch contacts 14, 15 and the longitudinal axis 16B of the movable switch contact 16 are parallel. Due to the current flow shown by the arrow, an electrodynamic force acts on the switch contacts 14 to 16. Since the fixed switch contacts 14, 15 and the movable switch contact 16 are flowed through by currents of the same orientation, a force F1 acting to attract the switch contacts is oriented such that it acts on the switch contacts. The force F1 is shown by an arrow in Figure 6 . Due to the current flow, a larger force F1 acts on the switch contacts, which results in the contact force becoming greater or the force required to close the switch becoming smaller. Thereby, the load on the conductive components is reduced. Thereby, the switching device can switch and conduct higher currents with the same dimensions as a conventional switching device.

[0056] Figure 8 A highly simplified schematic view of the switch contacts 14, 15, 16 is shown in a top view. In this illustration, the first and second fixed switch contacts 14, 15 are arranged above the movable switch contact 16. Current flows from the first fixed switch contact 14 through the movable switch contact 16 to the second fixed switch contact 15. The current direction is shown by A. The longitudinal axes of the switch contacts 14, 15, 16 are denoted by B. The regions where the contact faces 14A or 15A of the respective fixed switch contacts 14, 15 are in contact with the contact face 16A of the movable switch contact 16 (i.e., the effective contact regions) are indicated by diagonal lines. It can be seen that the contact faces or the effective contact regions extend in the current direction A, i.e., have a length l greater than the width b. The contact faces are longer than wide, preferably much longer.

[0057] Another aspect of the present invention is described hereinafter, which relates to the particular arrangement and configuration of the first or second conductors 10, 12. Figure 6 An embodiment is shown in which a conductor section 10B of the first conductor 10 is arranged in a region in front of the movable switch contact 16 in an orientation parallel to the movable switch contact 16, such that the movable switch contact moves from the open position to Figure 6moves away from the parallel-guided conductor section 10B of the first conductor 10 in the closed position shown.

[0058] In this embodiment, the parallel-guided conductor section 10B of the first conductor 10 is arranged in the same horizontal plane 28 as the switching contacts 14 to 16 of the switching device. The parallel-guided conductor section 10B, which preferably has a rectangular cross-section, can be a flat guide rail made of a conductive material such as copper. The conductor section 10B and the movable switching contact 16 are arranged with their wide sides facing each other. An exact parallel alignment of the wide sides (surfaces) is advantageous but not necessary. The flat conductors can also be slightly inclined relative to each other. The length of the conductor section 10B should be at least the same as the length of the movable switching contact 16. The conductor section 10B is firmly connected to the support 33 by means of the insulating section 32, and the support 33 can be fastened to the column 20 or other parts of the control cabinet 19. The fastening sections of the remaining conductor sections of the first conductor 10 and the fastening sections of the second conductor 12 are not shown.

[0059] The first conductor 10 has a conductor section 10A that electrically connects the first cable connection end 11 to the end portion of the parallel-guided conductor section 10B of the first conductor (the end portion on the side of the second fixed switching contact 15), and the first conductor 10 has a conductor section that electrically connects the end portion of the parallel-guided conductor section 10B of the first conductor (the end portion on the side of the first fixed switching contact 14) to the first device connection end or the first switching contact 14. The second conductor 12 connects the second switching contact 15 to the second cable connection end 13. Thus, the currents in the parallel conductor section 10B of the first conductor 10 and in the movable switching contact 16 flow in opposite directions. In this case of current flow, the parallel-guided fixed conductor section 10B and the movable switching contact 16 repel each other. Thereby, a compressive force is exerted on the movable switching contact 16, thereby increasing the contact force and minimizing the contact separation during switching.

[0060] Figure 7 A replacement embodiment is shown, which is related to Figure 6The difference between the embodiments only lies in that the first and second conductors 10, 12 are connected to the cable connection ends 11, 13. Corresponding parts to each other are denoted by the same reference numerals. In an alternative embodiment, instead of the first conductor 10, the second conductor 12 has a conductor section 12B that is guided parallel to the movable switch contact 16. The second conductor 12 has a conductor section 12A that electrically connects the second cable connection end 13 to the end portion of the conductor section 12B of the second conductor 12 that is guided parallel (this end portion is on the side of the first fixed switch contact 14), and the second conductor 12 has a conductor section 12C that electrically connects the end portion of the conductor section 12B that is guided parallel (this end portion is on the side of the second fixed switch contact 15) to the second device connection end 9 or the second switch contact 15. In this arrangement, the current in the conductor section 12B that is guided parallel and in the movable switch contact 16 also flows in opposite directions. Thus, the parallel conductor section 12B and the movable switch contact 16 repel each other accordingly.

[0061] However, in addition to the above embodiments, other embodiments are also possible, in which the first and second conductors 10, 12 are connected such that the direction of current flow is reversed, i.e., the current flows from the second fixed switch contact 15 through the movable switch contact 16 to the first fixed switch contact 14.

[0062] The first conductor may have a conductor section 10A that electrically connects the first cable connection end to the end portion of the conductor section of the first conductor that is guided parallel (this end portion is on the side of the first fixed switch contact), and the first conductor may have a conductor section that electrically connects the end portion of the conductor section of the first conductor that is guided parallel (this end portion is on the side of the second fixed switch contact) to the second device connection end or the second switch contact. The second conductor may connect the first fixed switch contact to the second cable connection end. The current in the conductor section of the first conductor that is guided parallel and in the movable switch contact thus flows in opposite directions. Thus, the conductor section that is guided parallel and the movable switch contact repel each other under the flow of current.

[0063] The first conductor may also connect the first cable connection end to the second fixed switch contact, where the second conductor has a conductor section that electrically connects the second cable connection end to the end portion of the conductor section of the second conductor that is guided parallel (this end portion is on the side of the second fixed switch contact), and the second conductor may have a conductor section that electrically connects the end portion of the conductor section of the second conductor that is guided parallel (this end portion is on the side of the first fixed switch contact) to the first fixed switch contact.

Claims

1. A switching device for a voltage limiting device, the switching device having a first fixed switch contact (14) electrically connected to a first device connection end (8), a second fixed switch contact (15) electrically connected to a second device connection end (9), a movable switch contact (16) which is movable between a closed position and an open position, in the closed position, the first and second fixed switch contacts (14, 15) are electrically connected to each other, and in the open position, the first and second fixed switch contacts (14, 15) are separated from each other, characterized in that the first and second fixed switch contacts (14, 15) are arranged side by side such that their contact surfaces (14A, 15A) face the same direction, and the movable switch contact (16) is arranged relative to the first and second fixed switch contacts (14, 15) such that the contact surface (16A) of the movable switch contact faces the contact surfaces (14A, 15A) of the first and second fixed switch contacts, wherein the first and second fixed switch contacts (14, 15) and the movable switch contact (16) form an arrangement of electrical conductors which are arranged substantially parallel to each other, so that during operation of the switching device, current flows through each switch contact in the same direction, and the contact surface (14A, 15A) of at least one of the fixed switch contacts (14, 15) is an elongated contact surface extending in the current flow direction A, the elongated contact surface being configured such that the corresponding fixed switch contact and the movable switch contact (16) are attracted to each other by the action of the electrodynamic force caused by the current flowing in the same direction, wherein the length (1) of the contact surface of at least one of the fixed switch contacts (14, 15) in the current flow direction (A) is at least twice the width (b) of the contact surface, wherein the movable switch contact (16) is pivotable about an axis (29) between the closed position and the open position, the axis extending parallel to the longitudinal axes (14B, 15B) of the first and second fixed switch contacts (14, 15).

2. The switching device according to claim 1, characterized in that, The first and second fixed switch contacts (14, 15) are linear electrical conductors having a rectangular cross-section.

3. The switching device according to claim 2, characterized in that, The first and second fixed switch contacts (14, 15) are arranged such that their wide sides form the contact surfaces (14A, 15A).

4. The switching device according to claim 1, characterized in that, The movable switch contact (16) is a linear electrical conductor having a rectangular cross-section.

5. The switching device according to claim 4, characterized in that, The movable switch contact (16) is arranged such that the wide side of the movable switch contact forms the contact surface (16A).

6. The switching device according to claim 1, characterized in that The length of the movable switch contact (16) is greater than or equal to the sum of the lengths of the first and second fixed switch contacts (14, 15) and the distance between the first and second fixed switch contacts (14, 15).

7. The switching device according to claim 1, characterized in that, The switching device has an actuating unit (17) which is designed to enable the movable switch contact (16) to move between the closed position and the open position.

8. A voltage limiting device, the voltage limiting device having a switching device (5) according to any one of claims 1 to 7.

9. The voltage limiting device according to claim 8, wherein It is provided with first and second cable connection ends (11, 13), wherein a first electrical conductor (10) electrically connects the first cable connection end (11) to a first device connection end (8) of the switching device (5), and a second electrical conductor (12) electrically connects the second cable connection end (13) to a second device connection end (9) of the switching device (5), wherein Conductor sections (10B, 12B) of the first or second electrical conductor (10, 12) are arranged in a region in front of the movable switching contact (16) in a direction substantially parallel to the movable switching contact (16), and in this region, the movable switching contact (16) moves away from the conductor sections (10B, 12B) when moving from the open position to the closed position.

10. The voltage limiting device according to claim 9, characterized in that, In the closed position of the movable switching contact (16), the conductor sections (10B, 12B) of the first or second electrical conductor (10, 12) arranged in front of the movable switching contact (16) with an orientation substantially parallel to the movable switching contact and the movable switching contact (16) are in one plane.

11. The voltage limiting device according to claim 10, wherein The conductor sections (10B, 12B) of the first or second electrical conductor (10, 12) arranged in front of the movable switching contact (16) with an orientation substantially parallel to the movable switching contact are straight electrical conductors having a rectangular cross-section.

12. The voltage limiting device according to claim 11, wherein The conductor sections (10B, 12B) of the first or second electrical conductor (10, 12) arranged in front of the movable switching contact (16) with an orientation substantially parallel to the movable switching contact are arranged such that the wide sides of the conductor sections face the movable switching contact (16).

13. The voltage limiting device according to any one of claims 8 to 12, characterized in that The conductor sections (10B, 12B) of the first or second electrical conductor (14, 15) arranged in front of the movable switching contact (16) with an orientation substantially parallel to the movable switching contact have a first end portion facing the first fixed switching contact (14) and a second end portion facing the second fixed switching contact (15), wherein The first electrical conductor (10) has a conductor section (10A) that extends from the first cable connection end (11) to the second end portion of the conductor section (10B) of the first electrical conductor (10) arranged in front of the movable switching contact (16) with an orientation substantially parallel to the movable switching contact, and has a conductor section (10C) that extends from the first end portion of the conductor section (10B) of the first electrical conductor (10) arranged in front of the movable switching contact (16) with an orientation parallel to the movable switching contact to the first device connection end (8) of the switching device (5), and The second electrical conductor (12) extends from the second device connection end (9) to the second cable connection end (13), or the first electrical conductor (10) extends from the first cable connection end (11) to the first device connection end (8), and the second electrical conductor (12) has a conductor section (12C) that extends from the second device connection end (9) to a second end portion of a conductor section (12B) of the second electrical conductor (12) that is arranged in front of the movable switch contact (16) in an orientation parallel to the movable switch contact, and has a conductor section (12A) that extends from a first end portion of a conductor section (12B) of the second electrical conductor (12) that is arranged in front of the movable switch contact (16) in an orientation parallel to the movable switch contact to the second cable connection end (13).

14. The voltage limiting device according to any one of claims 8 to 12, characterized in that The voltage limiting device is arranged in the control cabinet (19).

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