DEVICE AND METHOD FOR MONITORING AN ELECTRIC CONTACT COUPLING FOR RAIL VEHICLES

Abstract

The invention relates to a device and a method for monitoring an electrical contact coupling for rail vehicles, equipped with electrical contact elements and a mechanical cover that protects these contact elements from human contact when uncoupled. These devices and methods are intended to ensure the correct closing state of the cover of an electrical contact coupling equipped with electrical contact elements when uncoupled, thereby improving the operational reliability of the electrical power supply of the rail vehicle, and in particular, personal safety when handling electrical contact couplings.According to the invention, this is achieved in a device-oriented manner by the monitoring device comprising an ungrounded IT power supply circuit (11, 12) connecting the contact elements to a voltage source (10), an electrical switch (14) representing the mechanical closed state of the cover and connecting the IT power supply circuit (11, 12) to earth (13) or the voltage source (10), and a measuring means for detecting a current flow via the switch (14) during the operation of the IT power supply system.

Description

[0001] The invention relates to a device and a method for monitoring an electrical contact coupling for rail vehicles equipped with electrical contact elements and a mechanical cover that protects these contact elements against human contact when uncoupled.

[0002] In connection with the planned introduction of automatic train couplings on freight rail vehicles, the implementation of electrical couplings between these rail vehicles is also planned. These couplings will provide a 400 V power supply to the rail vehicles from a central unit of the train set equipped with a voltage source, usually its traction unit. In this case, personal safety must be ensured, particularly against accidental contact with live components of the electrical coupling. A particular problem here is the electrical coupling on the last vehicle in a train set, which is not coupled to a following rail vehicle, i.e., is in an uncoupled state.For this purpose, such an electrical coupling is protected against access by means of a mechanical cover that automatically closes under spring force when uncoupled. This is intended to prevent people from touching the coupling's live components. However, since such a mechanical cover always carries the risk of being incorrectly or completely closed, protection against contact with live components of the electrical coupling cannot be fully guaranteed.

[0003] Proposals are known from the prior art to equip such covers with separate contacts for verifying the correct mechanical closure of the cover. These contacts are interrogated via a bus system of the rail vehicle (for example, in the context of a train christening), and the rail vehicle's power supply can only be activated when a signal from these contacts is present indicating the mechanical closure of the cover. However, this requires a sufficient charge level of the vehicle's own battery storage system for such initial operation of the bus system without an activated power supply. This cannot, however, be guaranteed with sufficient reliability, particularly for rail vehicles that have previously been parked for an extended period.Particularly during longer downtimes, the charge level of the battery storage may have dropped to a level that is insufficient to operate the bus system without a power supply.

[0004] The invention is therefore based on the technical object of providing a device and a method for monitoring an electrical contact coupling for rail vehicles equipped with electrical contact elements and a mechanical cover that protects these contact elements against human contact when uncoupled, which enables an improvement in the operational reliability of the electrical power supply of the rail vehicle, in particular the personal safety when handling electrical contact couplings, and is independent of the operating state of the rail vehicle.

[0005] This is achieved according to the invention in a device-oriented manner in that the monitoring device has an ungrounded IT power supply circuit connecting the electrical contact elements to a voltage source, an electrical switch representing the closed state of the mechanical cover and connecting the IT power supply circuit to earth or the voltage source, and a measuring means for detecting a current flow via the switch during operation of the IT power supply system. In a method-oriented manner, this object is achieved in that the flow of a test current via an electrical switch representing the mechanical closed state of the cover and connecting an ungrounded IT power supply circuit connecting the contact elements to a voltage source to earth or the voltage source is monitored by means of measuring means during operation of the IT power supply system.

[0006] The electrical switch represents the mechanical closing state of the cover of the electrical contact coupling, in that when the cover is closed the switch of the associated electrical contact coupling is also closed and when the cover is open (or not properly closed) the switch is also open.

[0007] Such a monitoring device enables the detection of a test current flowing when the electrical switch is closed or when the cover of the electrical contact coupling is closed using the aforementioned measuring device, thus enabling monitoring of the closed state of the mechanical cover of the electrical contact coupling. The test current only flows when the switch is closed or when the cover of the electrical contact coupling is closed.If this switch, in the closed position, connects the IT power supply circuit to earth (for example, by establishing an electrically conductive connection via the vehicle chassis to the rail vehicle's running gear), the test current flows through the track bed and is detectable by a voltage source feeding the IT power supply circuit, which is installed on the same or another second rail vehicle electrically connected to the aforementioned rail vehicle and is also connected to earth there. When the electrical contact coupling is coupled, both its mechanical cover and the switch associated with this cover are in the open position, and no test current flows through this switch.

[0008] Alternatively, it is also conceivable for the electrical switch, in the closed position, to contact a dedicated electrically conductive return line to the voltage source of the IT power supply circuit. This prevents the test current from being conducted back via the track bed.

[0009] For this test current, which must be generated by the voltage source, a test voltage of a few volts is suitable, since a current flow in the milliampere range is sufficient for these testing purposes. Furthermore, the test voltage is designed as an alternating voltage in the range of a few hundred Hz to kilohertz. To avoid mutual interference, the frequency of the test voltage should not correspond to the harmonics of the operating voltage, the track detection systems, or the traction current of the rail vehicles (e.g., 16 2 / 3 Hz or 50 Hz). For this reason, a frequency of 417 Hz is preferred.

[0010] Several rail vehicles, each equipped with such a monitoring device according to the invention, can be coupled to form a train set, whose uncoupled electrical contact couplings at the front or rear of the train set are monitored for the closed state of their covers. The power supply lines of all vehicles are connected via the electrical contact couplings to a common IT power supply system covering the entire train set. Preferably, the aforementioned test voltage source is installed on the traction unit of the train set whose last coupling, or the one furthest from the traction unit, is monitored for the closed state of its cover.Since the covers of the coupled electrical contact couplings are open, the current flow of the test current to be detected by means of the device according to the invention is determined or enabled exclusively by the switch position of these uncoupled electrical contact couplings.

[0011] The invention thus enables a cost-effective safeguarding of the live components of the electrical contact coupling against accidental contact by humans, which can also be retrofitted to existing rail vehicles with comparatively little effort. During normal operation of the electrical contact coupling, the voltage source of the IT power supply circuit is switched off. According to a useful variant of the inventive concept, the usability of the IT power supply circuit is not limited to the aforementioned monitoring purposes using a test voltage, but can also be used - with appropriate adaptation of the electrical equipment - to supply power to other electrical consumers of the rail vehicle that are to be supplied via the electrical contact coupling during intended use.

[0012] According to the basic inventive concept, the monitoring device further comprises a means for interrupting the electrical connection between the switch and the IT power supply circuit. This means is only closed when the electrical contact coupling is de-energized; however, it is open when the electrical contact coupling is subjected to nominal voltage. Such an interruption means represents an additional safety measure to prevent a short circuit below nominal voltage.

[0013] This interruption device can either be actively switched, for example when switching the voltage supply of the IT power supply circuit from a test voltage to a nominal voltage of the rail vehicle consumers to be supplied electrically via the electrical contact coupling, or it can be automatically activated, for example when detecting a limit value being exceeded for the voltage applied to the IT power supply network (for example when the test voltage is exceeded).

[0014] Particularly preferably, the monitoring device further comprises a high-impedance resonant circuit connected in series with the means for interrupting the electrical connection between the switch and the IT power supply circuit and tuned to the test frequency. This resonant circuit serves as additional safety in case the aforementioned means for interrupting the electrical connection between the switch and the IT power supply circuit fails to respond, and should be designed with such high impedance that no significant short-circuit current can flow.

[0015] The present invention is explained in more detail below using an exemplary embodiment and the accompanying drawing. It shows: Fig. 1: Schematic representation of a train consisting of three rail vehicles each equipped with monitoring devices according to the invention

[0016] The Fig. The train shown in Figure 1 is formed of three rail vehicles, wherein the rail vehicles comprise a traction vehicle (101) leading the train and two wagons (102, 103) coupled thereto. These rail vehicles are coupled to each other by means of couplings (104), wherein each coupling (104) comprises both a mechanical coupling for transmitting mechanical forces between the rail vehicles and an electrical contact coupling for the electrically conductive connection of the electrical installations present on each rail vehicle. The couplings are in Fig. 1 shown only schematically for reasons of clarity. The electrical contact coupling of the "last" rail vehicle (103) in relation to the traction vehicle (101) located at the end of the train (or at the end of the train opposite the traction vehicle (101)) is in an uncoupled state, since no other rail vehicle is coupled to this last rail vehicle. Each electrical contact coupling has a mechanical cover (in Fig. 1 also not shown for reasons of clarity), which shields the electrical contact coupling in such an uncoupled state against access, in particular against contact by humans. In the coupled state of the electrical contact coupling, the cover is open; in the uncoupled state, the cover is closed. By means of a monitoring device, each cover is monitored for a correct or completely closed position. The present invention relates to the device and method-related design of such a monitoring device. This monitoring device according to the invention is formed from ▪ a voltage source (10) arranged on the traction vehicle (101), ▪ an IT power supply circuit to which a test voltage can be applied by this voltage source (10), comprising a first and second power supply line (11, 12) for each rail vehicle (102, 103), wherein the two power supply lines (11, 12) electrically connect the two front-end electrical contact couplings of each rail vehicle (102, 103) and can be coupled by means of the electrical contact couplings to form a power supply circuit extending over the entire train, including the traction vehicle (101), ▪ and a plurality of switches (14) which, when the switch is in the closed position, electrically connect the power supply lines (11, 12) of the IT power supply circuit to the car body or chassis of the respective rail vehicle (and in this way at the same time to earth (13)), wherein each cover of each electrical contact coupling of each rail vehicle (101, 102, 103) is uniquely assigned a switch (14) such that each switch (14) has a closed switch position when the cover is in the closed position or an open switch position when the cover is in the open position, ▪ and a measuring device for detecting a test current flow induced by the test voltage when one of the switches (14) is in the closed position via the aforementioned earth fault.

[0017] In the Fig. 1, the aforementioned measuring device is a functional component of the voltage source (10).

[0018] By means of this monitoring device, the Fig. 1, consisting of several rail vehicles (101, 102, 103), the monitoring of the correct closed position of the cover of the electrical contact coupling arranged at the end of the train. Such monitoring takes place, for example, when the train is put into operation as part of a so-called "train christening", so that the connection of a nominal voltage (e.g. of 400 V) to the power supply lines (11, 12) of the rail vehicles (101, 102, 103) can only take place after the closed position of the mechanical cover of the electrical contact coupling located at the end of the train has been successfully checked using a test voltage that is significantly lower than the nominal voltage. The covers of all electrical contact couplings in the coupled state are open; only the cover located at the end of the last rail vehicle (103) must be closed.

[0019] Thus, all switches (14) assigned to open covers are in the open position. In contrast, the switch monitoring the cover at the end of the train is in the closed position when this cover is correctly closed, so that the power supply lines (11, 12) of the IT power supply circuit are electrically connected to the chassis of the last rail vehicle (103) (as seen from the traction vehicle (101)) and thus also to earth (13). In this way, a test voltage fed into the power supply lines (11, 12) of the IT power supply circuit by the voltage source (10) results in a test current flow, which flows back to the traction vehicle (101) via the chassis and wheels of the last rail vehicle (103) and the track bed (105), where it can be detected by the measuring device.If the cover at the end of the train is open in the event of a fault, there will be no current flow from the (test) voltage source, which can be interpreted as a clear indicator of an open or insufficiently closed cover at the end of the train.

[0020] In this way, the correct closed position of the cover of the electrical contact coupling at the end of the train can be checked before applying the higher rated voltage (i.e., voltage exceeding the test voltage) to the power supply lines. During a train christening, for example, the power supply lines (11, 12) of the IT power supply circuit are initially subjected to a lower test voltage of a few volts and a frequency of 417 Hz from the voltage source (10).

[0021] Furthermore, the monitoring device is designed in such a way that the voltage source (10) alternately applies voltage to both phases (= positions “1” and “3” of the Fig. 1 shown voltage source (10) of the IT power supply circuit. This avoids bridging the two phases in the traction vehicle. If the result of the check of the closed state of the cover at the end of the train is correct, the voltage source (10) is completely disconnected from the supply network (= position "2" of the Fig. voltage source shown in Figure 1).

[0022] To increase the electrical safety of the monitoring device, a contact (15) is provided as an additional means for interrupting the electrical connection between each switch (14) and the power supply lines (11, 12) of the IT power supply circuit (in Fig. 1 (For reasons of clarity, only the electrical contact coupling at the end of the train is shown). The contacts (15) are closed in the de-energized state, allowing a test current induced by the test voltage to flow. However, the contacts (15) are opened as soon as the IT power supply circuit is supplied with a nominal voltage exceeding the test voltage.

[0023] Furthermore, the monitoring device has an impedance (16) connected in series with each contact (15) in the form of an oscillating circuit tuned to the test frequency (which in this example is selected as 417 Hz) and a series resistance in the kilo-ohm range (in Fig.1 (for reasons of clarity, this is also only shown for the electrical contact coupling at the end of the train), so that the line current flows through this switching device, provided that in the aforementioned case (i.e. the IT power supply circuit is under nominal voltage) the contacts K are nevertheless not open. List of reference symbols: 10 Voltage source 11, 12 Power supply line of an IT power supply circuit 13 Grounding 14 switches 15 switchable contact 16 Impedance of an oscillating circuit 101 locomotive of the train 102, 103 Rail vehicles of the train coupled to the traction unit (101) 104 Clutch 105 Trackbed

Claims

[1] Device for monitoring an electrical contact coupling for rail vehicles (101, 102, 103) equipped with electrical contact elements and a mechanical cover protecting these contact elements against human contact when uncoupled, characterized by that the monitoring device has an unearthed IT power supply circuit (11, 12) connecting the contact elements to a voltage source (10), an electrical switch (14) representing the mechanical closing state of the cover and connecting the IT power supply circuit (11, 12) to earth (13) or the voltage source (10), and a measuring means for detecting a current flow via the switch (14) during operation of the IT power supply system. [2] Device for monitoring an electrical contact coupling according to claim 1, characterized bythat the monitoring device further comprises a means (15) for interrupting the electrical connection between the switch (14) and the IT power supply circuit (11, 12). [3] Device for monitoring an electrical contact coupling according to claim 2, characterized by that the monitoring device further comprises a high-resistance resonant circuit having an impedance (16) connected in series with the means (15) for interrupting the electrical connection between the switch (14) and the IT power supply circuit (11, 12). [4] Method for monitoring an electrical contact coupling for rail vehicles (101, 102, 103) equipped with electrical contact elements and a mechanical cover protecting these contact elements against human contact when uncoupled, characterized bythat the current flow via an unearthed IT power supply circuit (11, 12) representing the mechanical closing state of the cover and connecting the contact elements to a voltage source (10) to earth (13) or the voltage source (10) is monitored by means of measuring means for the detection of a test current during operation of the IT power supply system.

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