Test device for DC railway system, DC railway system with test device and method

Abstract

The invention relates to a test device (10) for a DC railway system (1) for at least partially electrically powered rail vehicles, a DC railway system (1) with at least one test device (10) according to the invention, and a method for determining the total insulation resistance R. isoG (6) of a rail network (3) of a direct current railway system (1) with at least one test device (10) according to the invention. The invention makes it possible to easily detect a general deterioration of the overall insulation or a decrease in the general insulation properties of the DC railway system 1 over its entire route.

Description

[0001] The power supply for DC railway systems uses the two-wire principle, in which the electric current flows from the corresponding power sources, such as substations, via forward conductors, such as overhead lines, or feeder lines, and return conductors back to the power sources. Return current that escapes from the return conductor(s), such as rails, and flows through the ground is called stray current and can cause significant corrosion damage to metallic structures buried in the ground. To prevent such harmful stray currents as much as possible, DC railway systems, especially the rails, are constructed with insulation from the ground. This is achieved using insulators made of insulating materials that do not provide infinite insulation and therefore exhibit an undesirable insulation resistance. This insulation resistance...The resistance of the insulating materials used in the insulators is measured during the commissioning of the relevant traffic control system. Over the system's service life, the overall insulation typically deteriorates, and individual, localized insulation components may fail. Such locally occurring insulation defects can be readily detected by a known stray current monitoring system.

[0002] In the aforementioned stray current monitoring system, the voltage between the return conductor and the structure's earth, the so-called rail potential φ, is measured during ongoing railway operations. These measurements are taken at several points along the track of the railway system. During operation, the rail potential φ changes over time at each point depending on the passing trains. This results in a characteristic potential profile, a so-called "fingerprint," for each location along the track where measurements are taken. The current measured values ​​at each measuring point are compared with previously recorded reference values ​​for that location during evaluation. If the measured values ​​fall outside a specified tolerance range, a corresponding message is issued.As already mentioned, this allows for the reliable detection of local, point-source insulation faults along the route.

[0003] In contrast, a general deterioration of the overall insulation over the lifespan of the DC railway system, for example due to contamination, aging processes, etc., across the entire track or all track sections, is very difficult to detect using a stray current monitoring system. Therefore, corresponding insulation resistance measurements, as performed during the initial commissioning of the system, would need to be repeated at regular intervals throughout the years of operation. However, since precise specifications, particularly defined timeframes for repeat measurements, are lacking, and since such insulation resistance measurements, which are usually carried out outside of operating hours or when the track sections are in use, are very labor-intensive and require expert knowledge, such insulation resistance measurements are rarely performed on existing DC railway systems.

[0004] The invention is based on the objective of detecting a general deterioration of the overall insulation of a DC railway system in a simple way during its lifetime or operating period.

[0005] The problem is solved by the features of independent claim 1 and the dependent claims. Further developments and embodiments of the invention are found in the features of the dependent claims.

[0006] The test device according to the invention for a DC railway system for at least partially electrically powered rail vehicles, which is connected to the rail network of the DC railway system, comprises at least one switch and at least one test resistor R. testand at least one voltage source with a supply voltage U0, whereby a total insulation resistance R is determined by means of the test device with the switch closed and the supply voltage U0 applied. isoG of the rail network of the DC railway system can be determined, where the total insulation resistance R isoG can be determined at least by means of at least one insulation resistance, wherein the rail network of the DC railway system is isolated from the earth by means of the at least one insulation resistance.

[0007] The solution according to the invention has the advantage that by applying a fixed supply voltage U0 and closing the switch, the test resistor R test The test device is firmly connected to the earth and forms a series circuit, thus a voltage divider, consisting of the test resistor R. test and the total insulation resistance R isoGThis results in the following: The corresponding ratio of supply voltage U0 to the magnitude of the rail potential φ when the test device is switched on, which corresponds to the ratio of the sum of the test resistance R, can be calculated. test and total insulation resistance R isoG to the total insulation resistance R isoG This corresponds to an equation described in the following form: U0 / |φ|=(Rtest+RisoG) / RisoG, The total insulation resistance R can be determined in a simple way. isoG The relevant system can be calculated, since all other quantities are either known, such as the supply voltage U0 or the test resistor R. test, or can be easily measured, such as the rail potential φ. Since the longitudinal impedance across the tracks or rails is negligibly small, approximately 30 mOhm / km*rail, a substantially constant rail potential φ can therefore be assumed over the considered section of the DC railway system.

[0008] The measurement of the rail potential φ of the rail network can be carried out automatically. Appropriate measuring devices are usually already present in the relevant systems. If, for example, a stray current monitoring system is already present or installed in the system, a previously performed rail potential measurement can advantageously be used without additional effort or simply repeated. Due to the design of the test device, other auxiliary parameters, such as the defined current I, can also be used to verify the result. testand / or the voltage U test , which are above the test resistor R test Any drop in insulation can also be measured very easily and used as needed. Thus, a general deterioration of the overall insulation of a DC railway system can be detected along its entire length. Furthermore, the components required for constructing a test device according to the invention are very cost-effective. In addition, a test device according to the invention can be easily retrofitted into existing DC railway systems.

[0009] According to a further preferred embodiment of the invention, the voltage source of the test device is an AC voltage source or a DC voltage source. This allows for the advantageous use of virtually any existing voltage source already available on site, such as railway supply voltage, auxiliary voltages, power supplies, batteries, etc., depending on the requirements, taking into account a coordinated combination of voltage source, test resistor and current carrying capacity.

[0010] According to a further particularly preferred embodiment of the invention, when a supply voltage U0 > 50 volts AC or U0 > 120 volts DC is applied to the test device, at least one test resistor R test greater than the total insulation resistance R isoGIn the presence of such high, potentially dangerous voltages, this ensures that the greatest voltage drop occurs across the test resistor R during the measurements. test and is not present between the rail network and earth. This ensures that the applied rail potential φ of the rail network 3 poses no hazard and causes no further impairment. When a supply voltage U0 ≤ 50 volts AC or U0 ≤ 120 volts DC is applied to the test device, the test resistor R test However, it is also smaller than the total insulation resistance R isoG This can be chosen because in these cases the applied rail potential φ also poses no danger. Thus, the test resistor R can be testIn the case of using a voltage source with a very low supply voltage U0, for example, when using a 24-volt battery as the voltage source, the resistance can become very small and, with a sufficiently low supply voltage U0, in extreme cases even drop to 0 ohms or be set to 0 ohms. In this case, the total insulation resistance R can be mathematically determined using the following formula: isoG then the measurement of the rail potential φ and the current I test required or sufficient.

[0011] Another aspect of the present invention relates to a DC railway system for at least partially electrically powered rail vehicles, wherein the DC railway system comprises at least one substation and a rail network with a rail potential φ and at least one insulation resistance, wherein the rail network is insulated from earth by means of the at least one insulation resistance, with at least one test device according to one of claims 1 to 3.

[0012] According to a further embodiment of the DC railway system according to the invention, at least one test device is permanently installed in the DC railway system.

[0013] It is particularly preferred that at least one test device be permanently installed in at least one substation of the DC railway system.

[0014] In this way, the test device is permanently available for measurement purposes at any time. The test device's switch is open during operation of the DC railway system, thus disabling the test device. Thanks to the fixed and permanently installed test device, insulation resistance measurements can always be performed in the same way, virtually eliminating measurement errors caused by faulty setup or connections. No expert knowledge is required for the measurements themselves, meaning that no experts are needed. Therefore, measurements can be initiated by trained personnel and performed as often as required, for example, daily, weekly, monthly, etc.This allows for early intervention in the event of a decline in general insulation properties, thereby reducing costs and simultaneously increasing the safety of the entire system.

[0015] According to a further preferred embodiment of the DC railway system according to the invention, the DC railway system has at least one programmable unit, wherein the at least one programmable unit is configured such that the at least one programmable unit automatically regulates and / or controls the at least one test device.

[0016] In this way, the corresponding measurements can be triggered and carried out automatically, and the results of the measurement evaluation can be automatically transmitted and / or processed. Since no operation or traversal of the track should take place during the measurement(s) themselves, the measurements can therefore be carried out as a matter of course during nighttime hours without any additional personnel effort. "No operation" or "no traversal" refers exclusively to electric vehicles, i.e., vehicles powered by electricity from the designated supply system, such as overhead lines. Traversal by diesel-powered or battery-powered vehicles, for example, is also possible during the measurement.

[0017] Furthermore, the evaluation and its results can be used for other purposes, such as automated trend analyses. This further reduces the personnel effort and consequently the costs of such insulation resistance measurements.

[0018] Such a programmable unit can preferably be implemented as a suitably configured control and / or regulation device, etc., which automatically regulates or controls the test device or the sequence of the respective insulation resistance measurement procedure. Naturally, all other possible and appropriate programmable units are also included in the invention.

[0019] Another aspect of the present invention relates to a method for determining the total insulation resistance R. isoGa rail network of a direct current railway system according to one of claims 4 to 7 comprising the following steps: - Applying the supply voltage U0 to the test device; - Closing the switch of the test device of the DC railway system; - Measurement of the rail potential φ of the rail network; - Determination of the total insulation resistance R isoG of the rail network of the DC railway system according to the following relationship: RisoG=(|φ|*Rtest) / (U0−|φ|). U0 and R test are already known, so that by measuring the rail potential φ of the rail network in the corresponding step of the method according to the invention, the mathematical calculation of the total insulation resistance R is possible. isoG of the rail network of the DC railway system. The total insulation resistance R isoGThe rail network of the DC railway system can be mathematically determined not only by the rail potential φ but also by I. test or U test determine, which can also be determined very easily by corresponding, further measurements. If the rail potential φ has already been measured and is therefore known, the aforementioned further measurements are particularly useful for I. test or U test for the mathematical determination of the total insulation resistance R isoG of the rail network, as they are inherently redundant in this respect. However, if desired or necessary, they can be used to verify the already determined result for the total insulation resistance R. isoG of the rail network, e.g. through the further relationship RisoG=|φ| / Itest can be used accordingly. Of course, all other useful calculation methods are also available here, for example, by using the measured voltage U.test etc., included in the invention.

[0020] According to a further particularly preferred embodiment of the method according to the invention, the method is carried out automatically by means of the at least one programmable unit of the DC railway system.

[0021] The previously described features of the invention and, in particular, its advantages are transferable analogously to both the aforementioned direct current railway system and the aforementioned method and therefore apply accordingly to both and vice versa.

[0022] Preferred embodiments of the invention will now be explained in more detail with reference to the drawings. These show: Fig. 1 A schematic representation of an embodiment of a test device according to the invention in a DC railway system with the switch open and Fig. 2 a further schematic representation of the embodiment of a test device according to the invention in a DC railway system made of Fig. 1 with the switch closed.

[0023] In the Fig. In sections 1 and 2, identical components are designated with the same reference numerals. The embodiments may differ. The term "rail potential φ," used in the following figure description, refers to the potential in the... Fig. 1 and Fig. 2. Symbol ϕ used.

[0024] Fig. Figure 1 shows a schematic representation of an embodiment of a test device 10 according to the invention in a DC railway system 1. The representation is limited to the essential components of the invention, in particular of the DC railway system 1, etc., and therefore does not show all components of the DC railway system 1 in their entirety. The DC railway system 1 is intended for operation with at least partially electrically powered, rail-bound vehicles, such as electric rail vehicles of all kinds, etc.

[0025] According to Fig. Figure 1 of the DC railway system 1 shows a test device 10 permanently installed in a substation of the DC railway system 1, which is connected to the rail network 3 of the DC railway system 1 via connection 18. The substation itself is not shown for clarity. The test device 10 is thus permanently available at any time for insulation resistance measurements, allowing these measurements to be carried out as often as desired, for example, daily, weekly, monthly, etc. Because the test device 10 is permanently installed, measurements can always be performed in the same way, thus almost completely eliminating measurement errors caused by faulty setup or connections.

[0026] The rail network 3 with rail potential φ is insulated from earth 7 by means of the four spaced-apart insulation resistances 5 shown here as an example. The insulation resistances 5 are not to be understood as individual, real electrical components, but rather represent components in the equivalent circuit diagrams according to the Fig. 1 and Fig. 2 each the corresponding property of the insulators used or employed for the insulation of the rail network 3, which consist of insulating materials that do not insulate infinitely well and thus exhibit a corresponding, unwanted insulation resistance. The test device 10 has a voltage source 16 that can provide a supply voltage U0, a test resistor R test14 and a switch 12. The switch 12 is open, so the test device 12 is out of operation. This is the normal or usual case during the operation of the DC railway system 1. The voltage source 16 can be an AC voltage source or a DC voltage source, whereby the voltage supply is provided by considering a matched combination of voltage source 16, test resistor R test 14 and current-carrying capacity, advantageously almost all voltage sources already available on site, for example railway supply voltage, auxiliary voltages, power supplies, batteries, etc., can be used. The present DC railway system 1 is, for example, supplied by a railway supply voltage of 750 V, which is used as the supply voltage U0 of the voltage source 16 of the test device 10.

[0027] Fig. Figure 2 shows a further schematic representation of the embodiment of a test device 10 according to the invention in the DC railway system 1 made of Fig. 1 with switch 12 closed during an insulation resistance measurement.

[0028] To perform an insulation resistance measurement, a supply voltage U0 is first applied using the voltage source 16, and the test device 10 of the DC railway system 1 is activated by closing the switch 12. This activates the test resistor R. test 14 of the test device 10 is firmly connected to earth 7, creating a series circuit and thus a voltage divider, consisting of the test resistor R test 14 and a total insulation resistance R isoG 6, which, as shown in the equivalent circuit diagram according to Fig. 2 can be seen, composed of the individual insulation resistances 5. A current I then flows through the active circuit of the test device 10. testand above the test resistor R test 14 the voltage drops U test The rail potential φ then present on the rail network 3 of the DC railway system 1 generally differs from the rail potential φ before the test device 10 is activated and therefore has a different value. Regardless, in both cases the longitudinal impedance across the tracks or rails is negligibly small and is approximately 30 mΩ / km*rail, meaning that a substantially constant rail potential φ can be assumed over the considered section of the DC railway system.

[0029] Due to the creation or presence of the voltage divider through the activation of the test device 10, the following formula applies: the ratio of the supply voltage U0 to the magnitude of the rail potential φ when the test device 10 is switched on is equal to the ratio of the sum of the test resistance R. test14 and the total insulation resistance R isoG 6 to the total insulation resistance R isoG 6 corresponds to: U0 / |φ|=(Rtest+RisoG) / RisoG.

[0030] By simple mathematical transformation(s) of equation (1) the total insulation resistance R is obtained isoG 6 according to equation (2) then: RisoG=(|φ|*Rtest) / (U0−|φ|)

[0031] From this, the total insulation resistance R can be easily calculated. isoG 6 of the relevant Annex 1 are determined or calculated, since all other quantities are either known, such as the supply voltage U0 of the voltage source 16, as well as the test resistor R. test14, or can be easily measured, such as the rail potential φ. The measurement of the rail potential φ of the rail network 3 can be carried out automatically. Appropriate measuring devices are usually present in the relevant systems. If, for example, a stray current monitoring system is already present or installed in system 1, a previously performed rail potential measurement can be used without further additional effort or simply repeated. Due to the design of the test device 10, the obtained result for the total insulation resistance R can be verified. isoG 6 of the rail network 3 also other auxiliary quantities, such as the current I flowing when the test device 10 is actively switched on test and / or the voltage U test , which are above the test resistor R testThe 14 drops are also very easy to measure and can be used as needed.

[0032] Since the present voltage source 16 of the test device 10 is used as the supply voltage U0 of the railway supply voltage of 750 V and thus represents a high, potentially dangerous DC voltage > 120 volts, the test resistor R test 14 advantageously greater than the total insulation resistance R isoG 6 was chosen so that the greatest voltage drop would occur across the test resistor R. test 14 and not between rail network 3 of the DC railway system 1 and earth 7. This ensures that the adjacent rail potential φ of rail network 3 poses no danger and causes no further impairments.

[0033] In the present case, the DC railway system 1 also has a programmable unit, for example a correspondingly configured control and / or regulation device etc., which is not shown in the figures for the sake of clarity, and which automatically regulates or controls the test device 10 or the sequence of the procedure for the respective insulation resistance measurement described above.

[0034] This allows for automated triggering and execution of the corresponding measurements, as well as automated transmission and / or processing of the results. Since no operation or traversal of the track, particularly no rail traffic on rail network 3 of DC railway system 1, should take place during the measurement(s), the measurements can be carried out in this way without any additional personnel effort, typically during nighttime hours. "No operation" or "no traversal" refers exclusively to electric traversal, i.e., vehicles powered by electrical energy from DC railway system 1, for example, via an overhead line. Traversal of DC railway system 1 by, for example, diesel-powered or battery-powered vehicles is possible even during the measurement(s).

[0035] Furthermore, the evaluation and its results can be used for other purposes, such as automated trend analyses. Thus, a general deterioration of the overall insulation or a decline in the general insulation properties of the DC railway system 1 along its entire route can be easily detected, particularly at an early stage, using the invention, and countermeasures can be taken accordingly. This can reduce costs and simultaneously increase the safety of the entire system.

[0036] Furthermore, the invention is generally in no way limited to the invention described in the Fig. The invention is not limited to the embodiments described and shown in sections 1 and 2. Rather, all possible further meaningful embodiments of the invention are also fully encompassed.

Claims

[1] Test apparatus (10) for a DC railway system (1) for at least partially electrically powered rail vehicles, wherein the DC railway system (1) has a rail network (3) with at least one insulation resistance (5) and wherein the rail network (3) is insulated from earth (7) by means of the at least one insulation resistance (5), wherein the test apparatus (10) is connected to the rail network (3) of the DC railway system (1), characterized by that the test device (10) has at least one switch (12), at least one test resistor R test (14) and has at least one voltage source (16) with a supply voltage U0, wherein a total insulation resistance R is determined by means of the test device (10) with the switch (12) closed and the supply voltage U0 applied. isoG (6) of the rail network (3) of the DC railway system (1) can be determined, wherein the total insulation resistance R isoG(6) can be determined at least by means of the at least one insulation resistance (5). [2] Test device (10) according to claim 1, characterized by , that the voltage source (16) of the test device (10) is an alternating voltage source or a direct voltage source. [3] Test device (10) according to claim 1 or 2, characterized by , that when a supply voltage U0 > 50 volts AC or U0 > 120 volts DC is applied to the test device (10), at least one test resistor (14) is greater than the total insulation resistance R isoG (6) is. [4] DC railway system (1) for at least partially electrically powered rail vehicles, wherein the DC railway system (1) comprises at least one substation and a rail network (3) with a rail potential φ and at least one insulation resistance (5), wherein the rail network (3) is insulated from earth (7) by means of the at least one insulation resistance (5), with at least one test device (10) according to one of claims 1 to 3, [5] DC railway system (1) according to claim 4, characterized by , that at least one test device (10) is permanently installed in the DC railway system (1). [6] DC railway system (1) according to claim 5, characterized by , that at least one test device (10) is permanently installed in at least one substation of the DC railway system (1). [7] Direct current railway system (1) according to any one of claims 4 to 6, characterized by, that the DC railway system (1) has at least one programmable unit, wherein the at least one programmable unit is configured such that the at least one programmable unit automatically regulates and / or controls the at least one test device (10). [8] Method for determining the total insulation resistance R isoG (6) of a rail network (3) of a direct current railway system (1) according to one of claims 4 to 7 comprising the following steps: - Applying the supply voltage U0 to the test device (10); - Closing the switch (12) of the test device (10) of the DC railway system (1); - Measurement of the rail potential φ of the rail network (3); - Determination of the total insulation resistance R isoG (6) of the rail network (3) of the DC railway system (1) according to the following relationship: RisoG=(|φ|*Rtest) / (U0−|φ|) [9] Method according to claim 8, characterized by, that the procedure is carried out automatically by means of at least one programmable unit of the DC railway system (1).

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