Control device for electrically switchable brake valves

Abstract

The invention relates to a generic control device for electrically switchable brake valves of vehicles that can be coupled into a train set with at least one leading vehicle (A), comprising an electrical transmission means (5) comprising at least a first wire (51) and a second wire (52) for supplying current to the brake valves. This device is intended to increase the reliability of electropneumatic brake control, even in very long train sets. This is achieved in that the control device further comprises: a switchable wire interruption means (50) acting synchronously on both wires (51, 52) at a respective first interruption contact (510, 520) between the first coupling means (513, 523) and the second coupling means (514, 524), a second DC voltage source (53) switchable by means of the wire interruption means (50) for generating a second control voltage, wherein the second DC voltage source (53) is connected to both wires (51,52) is electrically conductively connected in each case in two feed points (K, P; L, O) arranged between the first interruption contact (510, 520) and the second coupling means (514, 524), and wherein an interruption of the wires (51, 52) by means of the wire interruption means (50) causes the second DC voltage source (53) to be switched on, a switching means (54) designed as a relay and connected in a current direction-dependent manner between the first coupling means (513, 523) and the first interruption contact (510, 520) in the electrical transmission means (5) for switching the polarity of the second control voltage, and at least one switching means (54) designed as a relay and connected in a current direction-independent manner between the first coupling means (513, 523) and the first interruption contact (510, 520) in the electrical transmission means (5), which is dependent on the connection of the second DC voltage source (53) interrupting means (55) acting in the electrical transmission means (5).,

Description

The invention relates to a control device for electrically switchable brake valves of vehicles that can be coupled into a train set having at least one leading vehicle, having an electrical transmission means comprising at least a first wire and a second wire for energizing the brake valves by means of a first control voltage that can be fed into the transmission means by a first DC voltage source on the leading vehicle, wherein both wires can be electrically coupled by means of first coupling means to an adjacent vehicle running ahead in the train set and by means of second coupling means to an adjacent vehicle running behind in the train set.DE 32 09 157 A1 discloses a system for monitoring the safety state of a train consisting of a plurality of track-bound vehicles, in which two monitoring elements each performing a monitoring function (e.g. door closure, train completion) are connected by means of separate monitoring lines which are fed at opposite ends of the train from a common power supply loop running through the entire train.CH 474 931 A discloses a device for automatically controlling and detecting processes within a train, which device is based on an electrical transmission of commands between the vehicles of the train by means of correspondingly configured transmitters and receivers on the vehicles and represents an early precursor of later train bus transmission systems.The braking of moving rail vehicles is usually carried out by means of pneumatically controlled indirect compressed air brakes. For this purpose, all vehicles of a train unit are connected to one another by means of a continuous air line (so-called "main air line"). A pressure reduction in the main air line controls the brake system of each individual vehicle into a braking state. Even in the event of an undesired pressure reduction in the main air line, for example caused by a leak or a separation of the train assembly between two vehicles, the brake is activated in all vehicles, in particular also the vehicles separated from the train assembly. However, the time delay in the propagation of the pressure drop in the main air line from a leading vehicle controlling the pressure in the main air line in the direction of the vehicles of the train set is disadvantageous, as a result of which the braking action begins later with increasing distance from the leading vehicle in each vehicle controlled by means of the pressure drop in the main air line. As a result, in particular in the case of long trains, vehicles which have not yet been braked can push on the train closure against vehicles which have already been braked in the front train part lying in front of the train. To remedy these problems, electropneumatic brake devices for rail vehicles have been known for a long time, in which the pressure in the main air line can be influenced by means of electrically switchable brake valves. This enables electrically transmitted brake request signals to be present simultaneously on all brakes of all rail vehicles in the entire train set. In this way, a braking action which initiates simultaneously on all brakes in the entire train is achieved and the dynamic longitudinal forces in the train combination are reduced to a minimum. The brake valves are usually designed as electrically controllable solenoid valves. Such electropneumatic brake devices have become established in Europe as a standard for trains of cars guided by means of traction vehicles. The electrical brake and release signals are generated in the leading traction vehicle in parallel with the control of the pressure in the main air line and are transmitted via electrical lines into all vehicles of the train set. This achieves a simultaneous control of the relevant brake or release valves in the entire train assembly.Hitherto, such electropneumatic brakes have been used almost exclusively in rail vehicles serving for passenger traffic. According to a more recent development, however, an electropneumatic brake control can also be realized, in which the ventilation support of the main air line takes place in the non-energized state of the brake valve and is therefore fully functional even in the case of a traction disconnection. The advantages of an electropneumatic brake should therefore also be utilized for freight traffic. The invention is therefore based on the technical object of providing a generic control device for electrically switchable brake valves of vehicles which can be coupled into a train assembly having at least one leading vehicle, which control device increases the reliability of the electropneumatic brake control even in the case of train assemblies which are very long or formed from very many guided cars.This is achieved according to the invention in that the control device further comprises: a switchable core interrupting means acting synchronously on both cores at a respective first interruption contact between first coupling means and second coupling means,▪ a second DC voltage source, switchable by means of the core interrupting means, for generating a second control voltage, wherein the second DC voltage source is electrically conductively connected to both cores in in each case two feed points arranged between the first interrupting contact and the second coupling means, and wherein an interruption of the cores by means of the core interrupting means brings about an activation of the second DC voltage source,▪ a switching means, which is embodied as a relay and is connected between the first coupling means and the first break contact in the electrical transmission means in a current-direction-dependent manner, for switching the polarity of the second control voltage,▪ at least one interruption means, which is embodied as a relay and is connected independently of the current direction between the first coupling means and the first interruption contact in the electrical transmission means and acts on the connection of the second direct voltage source in the electrical transmission means.In this way, a control device can be realized, by means of which a rail vehicle equipped according to the invention receives a first control signal generated by means of the first DC voltage source on a rail vehicle running ahead in the train unit (generally on a traction vehicle guiding the train unit) and passes on a second control signal identical thereto in a time-synchronous manner (i.e. without a time delay) to the rail vehicles running behind in the train unit. This enables a repeater operation for the control of the electromagnetic brake valves of the trailing rail vehicles, which enables repetition or amplification of the control signal along the transmission path by the train unit and increases the reliability of the control. It is sufficient if only one or a few individual vehicles of the train set are equipped with such a control device or repeater functionality according to the invention. These act as signal amplifiers or repeaters within the train set in which they are set with respect to the rail vehicles respectively running behind them. The first drive signal is based on the first control voltage generated by means of the first DC voltage source; the repeater drive signal generated by means of the drive device according to the invention is based on the second control voltage generated by means of the second DC voltage source of the rail vehicle configured to implement the repeater functionality. Usually, the first and second control voltages are identical to each other, but can also deviate from each other, provided that there is a cause for this purpose from the point of view of the person skilled in the art involved in the realization of such a control device.A rail vehicle equipped with a control device according to the invention has first and second coupling means which are electrically conductively connected to one another by means of a respective cable and by means of which the rail vehicle can be coupled to the electrical transmission means of adjacent rail vehicles running ahead or running behind in the same train set. By means of the aforementioned cable interrupting means which acts synchronously on both cables of the electrical transmission means at a respective first interruption contact between the first and second coupling means, the control device according to the invention of a rail vehicle equipped in this way can be switched from a first operating state, in which both first interruption contacts are closed and thus a first control signal generated by means of the first DC voltage source is passed through via the uninterrupted cables of the electrical transmission means between first and second coupling means to an adjacent rail vehicle running behind in the train, to a second operating state (the so-called "repeater operation"), in which, based on the first control voltage received via the first coupling means from the leading adjacent rail vehicle, a second control signal for the brake valves of the train set based on the second control voltage generated by the second DC voltage source is generated and transmitted via the second coupling means to the trailing adjacent rail vehicle. In order to avoid mixing of incoming and generated control signals, when switching from the first to the second operating state or when switching on the repeater operation, both wires of the electrical transmission means are interrupted by means of the wire interrupting means, the actuation of which simultaneously switches on the second direct voltage source.The polarity changeover of the second control voltage generated by this second DC voltage source takes place via a relay which is connected between the first coupling means and the abovementioned break contacts of the two cores as a function of the current direction. The current supply to this relay or means for switching over the polarity of the second control voltage is thus coupled directly to the polarity of the first control voltage. The current direction dependence of the electrical integration of this relay into the repeater circuit according to the invention is preferably realized by means of a blocking diode connected in series with the relay. In order to generate a braking signal to be transmitted to the following vehicle, at least one further relay is likewise provided which is connected between the first coupling means and the abovementioned break contacts of the two cores independently of the current direction and acts as a break means on both cores of the electrical connection of the second DC voltage source to the two cores of the electrical transmission means in the non-energized state. In this way, it is ensured that, in the event of an interruption of the first control voltage (for example by wire interruption means, by means of which the first control voltage can be interrupted on the leading traction vehicle in the event of operating, rapid or full braking initiated by the brake control or by action of a train safety system), an interruption of the second control voltage likewise takes place. To increase redundancy and safety with respect to possible functional failures (e.g. sticking of the relay despite no current flow), a series connection of a plurality of similar relays can be provided for this purpose. The number of series-connected relays can be increased with increasing safety level. The current direction independence of the electrical integration of this at least one further relay into the repeater circuit according to the invention is preferably realized by means of a rectifier circuit connected in series with the at least one relay.These relays provided as switching means of the polarity of the second control voltage or as interrupting means of the second control voltage can additionally be switched on or off by means of the aforementioned wire interrupting means, so that they are activated only when repeater operation is switched on.According to a reasonable further development of the inventive idea, the control device further comprises:▪ a bridging means, which is designed as a relay and is energized by means of the second DC voltage source, of a second break contact in each wire,▪ wherein both second break contacts are respectively arranged between the feed points of the second voltage source and the second coupling means of each core and can be switched synchronously to the first break contacts by means of the core break means,▪ a first interruption means, which is embodied as a relay and is connected independently of the current direction between the first coupling means and the first interruption contact in the electrical transmission means and acts on the energization of the bridging means,▪ and a second interruption means, which is embodied as a relay and is connected independently of the current direction between the feed points of the second voltage source and the second interruption contact of each wire in the electrical transmission means and acts on the energization of the bridging means.In this way, a control device can be realized in which the control signals generated by the leading traction vehicle and present or arriving at the first coupling means and originating can be mutually balanced. This increases the safety level of a control device according to the invention in repeater operation. In such a "balancing circuit", an additional break contact is provided on each of the two wires of the electrical transmission means in a region between the feed point of the repeater signals into the wire and the second coupling means to the trailing adjacent vehicle, which can be bridged by means of a powered relay, wherein the bridging should have at least the same wire cross section. The current supply to this bridging relay takes place via the aforementioned second DC voltage source and can be interrupted via two further relays. A first of these two interrupter relays can be controlled via the incoming drive signals, and the second can be controlled via the outgoing drive signals. For this purpose, the first interrupter relay is connected independently of the current direction between the first coupling means and the first interrupter contacts in the electrical transmission means, and the second interrupter relay is connected independently of the current direction between the feed points of the second voltage source into the wires of the electrical transmission means and the second interrupter contact of each wire in the electrical transmission means. The energization of the bridging relay is thus only possible if both the first control voltage is present at the first coupling means (which, in the sense of this inventive idea described here, is to be understood as an activation signal arriving from the leading traction vehicle) and the second control voltage is present between the feed points of the second voltage source into the wires of the electrical transmission means (which, in this context, is to be understood as an outgoing activation signal generated by the inventive activation device in repeater operation). If the outgoing drive signal generated by the drive device in the repeater mode does not correspond to the incoming drive signal generated on the leading traction vehicle, the above-mentioned bridging relay remains unenergized and the above-mentioned additional break contact in the wires of the electrical transmission means remains unbridged. Thus, the drive signals generated during repeater operation of the drive device are not transmitted to following vehicles via the second coupling means.The present invention is explained in more detail below with reference to an exemplary embodiment and associated drawings. It shows: FIG. 1 : Circuit diagram of a control device known from the prior art for electrically switchable brake valves in relation to the leading vehicle of a train set FIG. 2 : Circuit diagram of a control device, set up for repeater operation by means of a repeater circuit according to the invention, of a following vehicle which is placed in the train set FIG. 3 : Circuit diagram of the vehicle according to FIG. 2 set up for repeater operation, supplemented by a matching circuit likewise according to the inventionFor better visual recognition of the actual invention, the figures of the exemplary embodiment schematically show exclusively the electrical integration of the control device into a train set formed from a leading traction vehicle (A) and a plurality of guided vehicles (B, C), one of these guided vehicles (B) of the train set being equipped with a repeater circuit according to FIG. 2 and a matching circuit according to FIG. 3. In the context of this exemplary embodiment, the guided vehicle (B) is a further traction vehicle which is lined up in the train unit for increasing the tractive force and can be remotely controlled by the guiding traction vehicle (A). In the pneumatic aspect (not shown in the figures), all vehicles of the train unit are connected to one another by means of a main air line, wherein the main air lines of adjacent vehicles can be coupled pneumatically continuously by means of connecting hoses. A pressure reduction in the main air line controls the brake system of each guided vehicle into a braking state. In the figures of the exemplary embodiment, the illustration of the electrical control of the brake valves as such is also omitted, since this is not the focus of the inventive idea explained here.The circuit diagrams illustrated in the figures of the exemplary embodiment visualize the control device in each case in a current- and pressure-free state, wherein all actuating devices are illustrated in an unactuated initial state.In electrical terms, all guided vehicles (B, C) of the train are connected by means of an electrical transmission means (5) formed from two wires (51, 52) for transmitting electrical brake request signals to the brakes of the vehicles, wherein the wires (51, 52) thereof can be electrically connected by means of first coupling means (513, 523) and second coupling means (514, 524) between two adjacent vehicles of the same train. The electrical brake and release signals provided for controlling the brake valves of each guided vehicle (not shown in the figures) are generated in the guiding vehicle (A) by means of a control circuit there parallel to the control of the pressure in the main air line and are transmitted via the wires (41, 42; 51, 52) of the electrical transmission means (4; 5) to each guided vehicle (B, C) of the train.The leading vehicle (A) schematically visualized in FIG. 1 has a first direct voltage source (43), which can be switched on or off, for generating a first control voltage that can be transmitted to each leading vehicle (B, C) via the cores (41, 42) of the electrical transmission means (4), a switching means (46), which is designed as a relay, for switching the polarity of this first control voltage, and a core interruption means (471), which acts on both cores (41, 42) and by means of which the control voltage can be interrupted in the event of an operating, rapid or full braking initiated by the brake control. In addition, further core interrupting means ( 472, 473) are provided which act on both cores ( 41, 42) in each case and by means of which the control voltage can be interrupted, for example in the event of rapid braking initiated by a traction protection system (not shown in more detail in FIG. 1 ).The guided vehicle (B), which is likewise schematically visualized in FIGS. 2 and 3, likewise has an electrical transmission means (5), the two cores (51, 52) of which can be conductively connected to the respective cores (41, 42) of the electrical transmission means (4) of the guiding vehicle (A) via first coupling means (513, 523), wherein a plurality of further guided vehicles (not illustrated in the exemplary embodiment for reasons of clarity) can be arranged in line between the two vehicles. Furthermore, the electrical transmission means (5) of the guided vehicle (B) can be conductively connected to the electrical transmission means of a following, further guided vehicle (C) via second coupling means (514, 524).The repeater circuit according to the invention shown in FIG. 2 of the control device according to the invention on the guided vehicle (B) is formed from a manually switchable core interrupting means (50) which acts on first interrupting contacts (510, 520) in both cores (51, 52) of the electrical transmission means (5). Upon activating the operation of this repeater circuit (referred to as "repeater operation" in the context of this invention), both break contacts (510, 520) are opened synchronously and thus the transmission of drive signals between the first coupling means (513, 523) and the second coupling means (514, 524) is interrupted.Furthermore, the repeater circuit comprises a second direct voltage source (53), which can be switched by means of the core interrupting means (50) and generates a second control voltage and the outputs of which are electrically conductively connected to the two cores (51, 52) in in each case two feed points (K, L, O, P) arranged between the first interrupting contact (510, 520) and the second coupling means (514, 524). When the repeater operation is activated by means of the core interrupting means (50), the second DC voltage source (53) is simultaneously switched on via the switches (530).A relay ( 54), which is connected by means of a blocking diode ( 541) between first coupling means ( 513, 523) and first interruption contacts ( 510, 520) in each case to the wires ( 51, 52) of the electrical transmission means ( 5) as a function of the current direction, serves for switching over the polarity of the second control voltage. When the repeater operation is activated by means of the core interrupting means (50), this relay (54), which switches over the polarity, is also simultaneously switched on via the switches (540). The current supply to this relay ( 54) or means for switching over the polarity of the second control voltage is thus directly coupled to the polarity of the first control voltage.Furthermore, the repeater circuit comprises three relays ( 55) connected in series with one another, which each act as interrupting means on the interconnection of the second DC voltage source ( 53) in the electrical transmission means ( 5). These relays ( 55) are connected to the wires ( 51, 52) of the electrical transmission means ( 5) by means of a parallel-connected rectifier circuit ( 551) independently of the current direction between the first coupling means ( 513, 523) and the first interruption contacts ( 510, 520). When the repeater operation is activated by means of the core interrupting means ( 50), each of these interrupting relays ( 55) is simultaneously also energized via the switches ( 550). In the energized state, the switching contacts of the interruption relays (55) are closed and the second control voltage generated by the second DC voltage source (53) is present-depending on the polarity set by means of the relay (54)-at the feed points K and P (or L and O) at the wires (51, 52) or the second coupling means (514, 524). In the non-energized state, on the other hand, the interruption relays ( 55) drop off and open both wires of the electrical connection of the second DC voltage source ( 53) to the feed points (K, O). In this way, it is ensured that, in the event of an interruption of the first control voltage (for example by the core interruption means ( 471, 472, 473), by means of which the first control voltage can be interrupted on the leading vehicle (A) in the event of an operating, rapid or full braking initiated by a brake control or by the action of a train safety system), the second control voltage is likewise interrupted in the control device of the guided vehicle (B). By means of a series connection of a plurality of relays ( 55) of the same type, the redundancy of the control device with respect to possible functional failures (e.g. sticking of a relay despite the absence of current supply) is increased.By actuating the core interrupting means (50), the control device can be switched between a first operating state in which both first interrupting contacts (510, 520) are closed and thus a first control signal generated by means of the first DC voltage source (43) is passed via the first coupling means (513, 523), the uninterrupted cores (52, 52) and the second coupling means (514, 524) to an adjacent rail vehicle (C) trailing in the train train, and a second operating state (repeater operation) in which both first interrupting contacts (510, 520) are open and in which a second control signal is generated by means of the second DC voltage source (53) as a function of the control signal arriving via the first coupling means (513, 523) and is fed via the feed points (K, L, O, P) to the second coupling means (514, 524) for transmission to a trailing adjacent rail vehicle (C), wherein the polarity of said second control signal corresponds to the polarity of the first control signal or changes synchronously therewith, and wherein an interruption of the first control voltage causes a synchronous interruption of the second control voltage.FIG. 3 shows a calibration circuit which supplements the repeater circuit visualized in FIG. 2 and increases the operational safety of the control device. This balancing circuit visualized in FIG. 3 is therefore realized on the same guided vehicle (B) as the repeater circuit shown in FIG. 2 and together with this forms a control device according to the invention. In addition to the repeater circuit shown in FIG. 2, the control device has in each case a second break contact (511, 521) in both wires (51, 52) between the respective feed points (K, L, O, P) of the second DC voltage source (53) and the respective second coupling means (514, 524). These second break contacts (511, 521) can be bridged by means of a switching contact (518, 528) in each case, wherein both switching contacts (518, 528) can be switched by means of a bridging relay (58) energized by the second direct voltage source (53). For this purpose, the relay ( 58) is electrically conductively connected to the second DC voltage source ( 53) at the connection points (M, N). In the energized state of the bridging relay ( 58), both switching contacts ( 518, 528) are closed and the second interruption means ( 511, 521) are thus bridged.Furthermore, the balancing circuit of the drive device comprises a first interruption relay (56) acting on the energization of the bridging relay (58), which is connected between the first coupling means (513, 523) and the first interruption contacts (510, 520) in the electrical transmission means (5) independently of the current direction by means of a rectifier circuit (561), and a second interruption relay (57) acting on the energization of the bridging relay (58), which is connected between the feed points (K, L, O, P) of the second voltage source (53) and the second interruption contacts (511, 521) of each wire in the electrical transmission means independently of the current direction by means of a further rectifier circuit (571). The first interrupter relay ( 56) can thus be controlled as a function of the first control signals which are present at the two first coupling means ( 513, 523) and are generated on the leading vehicle (A) by means of the first direct voltage source ( 43) there. The second interrupter relay ( 57), on the other hand, is controllable as a function of the second drive signals generated in the guided vehicle (B) during repeater operation by means of the second direct voltage source ( 53), said second drive signals being present at the feed points (K, L, O, P). The energization of the bridging relay ( 58) is therefore only possible when both the first interrupter relay ( 56) is energized (or the first control voltage is present at the first coupling means ( 513, 523)) and the second interrupter relay ( 57) is energized (or the second control voltage is present at the feed points (K, L, O, P) of the second voltage source ( 53)). Otherwise, the second drive signals generated during the repeater operation of the drive device are not provided to the second coupling means ( 514, 524) for transmission to following vehicles.In this way, a comparison is made between the first (or "incoming") control signals generated by the leading traction vehicle and present at the first coupling means ( 513, 523) and the second control signals available (or "outgoing") at the second coupling means ( 514, 524) for forwarding to the following vehicle.List of reference numbers:A guiding vehicle of train B first guided vehicle with repeater circuit C according to the invention further guided vehicle of train K,L,O,P feed points of the second control voltage M,N connections of the voltage supply of bridging relay (58) 4 electrical transmission means of the guiding vehicle (A) 41 first wire of electrical transmission means (4) 42 second wire of electrical transmission means (4) 43 first direct voltage source for generating a first control voltage 46 switching means for changing the polarity of the first control voltage 471 interruption means for operating, full and rapid braking; controllable by brake controller 472 interruption means, Actuatable by train protection system 473: Interruption means during rapid braking 5: Electrical transmission means of a guided vehicle (B) with repeater functionality 50: Wire interruption means 51: First wire of the electrical transmission means (5) 52: Second wire of the electrical transmission means (5) 510, 520: First interruption contact 511, 521: Second interruption contact 513, 523: First coupling means to the adjacent vehicle running ahead 514, 524: Second coupling means to the adjacent vehicle running behind 518, 528: Switching contacts to bridge the second interruption contact (511, 521) 53 second DC voltage source for generating a second control voltage 530 on / off contact of the second DC voltage source (53) 54 switching relay for polarity change of the second control voltage 540 on / off contact of the switching relay (54) 541 blocking diode 55 interruption relay 550 on / off contact of the interruption relays (55) 551 rectifying circuit 56, 57 interruption relay 560 on / off contact of the interruption relay (56) 561, 571 rectifying circuit 58 relay for bridging the second interruption contact (511, 521)

Claims

Control device for electrically switchable brake valves of vehicles which can be coupled into a train with at least one leading vehicle (A), having an electrical transmission means (5) which comprises at least one first core (51) and a second core (52) and which supplies current to the brake valves by means of a first control voltage which can be fed into the transmission means (5) by a first direct voltage source (43) on the leading vehicle (A), wherein both cores (51, 52) can be electrically coupled by means of first coupling means (513, 523) to an adjacent vehicle which runs ahead in the train and by means of second coupling means (514, 524) to an adjacent vehicle which runs behind in the train, characterized in that the control device furthermore has ▪ a first interruption contact (510, 520) between first coupling means (513, which is synchronous with both cores (51, 52), 523) and second coupling means (514, 524), acting switchable core interrupting means (50), ▪ a second direct voltage source (53), switchable by means of the core interrupting means (50), for generating a second control voltage, wherein the second direct voltage source (53) with both cores (51, 52) is fed into two feed points (K, P; 523) respectively arranged between the first interrupting contact (510, 520) and the second coupling means (514, 524); l, o) is electrically conductively connected, and wherein an interruption of the wires (51, 52) by means of the wire interruption means (50) causes the second DC voltage source (53) to be switched on, ▪ a switching means (54), which is designed as a relay and is connected in the electrical transmission means (5) in a manner dependent on the direction of current, for switching the polarity of the second control voltage, ▪ at least one interruption means (55), which is designed as a relay and is connected in the electrical transmission means (5) in a manner independent of the direction of current, between the first coupling means (513, 523) and the first interruption contact (510, 520), and acts on the connection of the second DC voltage source (53) in the electrical transmission means (5) and acts on the connection of the second DC voltage source (53) in the electrical transmission means (5).Control device for electrically switchable brake valves according to claim 1, characterised in that the control device further comprises: ▪ a bridging means (58), which is designed as a relay and is energized by means of the second direct voltage source (53), of a second break contact (511, 521) in each core (51, 52), ▪ wherein both second break contacts (511, 521) each between the feed points (K, P; l, o) of the second voltage source (53) and the second coupling means (514, 524) of each conductor (51, 52) and can be switched synchronously with the first interruption contacts (510, 520) by means of the conductor interruption means (50), ▪ a first interruption means (56), ▪, which is designed as a relay and is connected independently of the current direction between the first coupling means (513, 523) and the first interruption contact (510, 520) in the electrical transmission means (5) and acts on the energization of the bridging means (58), and a second interruption means (56), ▪, which is designed as a relay and is connected independently of the current direction between the feed points (K, P; l, o) of the second voltage source ( 53) and of the second interruption contact ( 511, 521) of each core ( 51, 52) in the electrical transmission means ( 5) connected interruption means ( 57) which acts on the energization of the bridging means ( 58).

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