HK1058341B - Process and installation for detecting a rail break - Google Patents

Description

Method and apparatus for detecting rail break

The technical field is as follows:

the invention relates to a method for monitoring the integrity of a railway track, in particular to a method for detecting rail breakage.

The invention also relates to a device for implementing the method.

Background art:

some railway transport drivers, and indeed all such drivers of certain types of traffic such as passenger transport routes, routes having speeds in excess of 160km/h, etc., require an autonomous real-time system on the ground to detect rail breaks. In practice, the term "real-time" is understood to mean a delay of at most a few minutes in response to a command.

It is in fact absolutely necessary to detect rail breaks in time, since rail breaks, particularly in curved track sections, can lead to major accidents, such as derailments.

Moreover, after the occurrence of the primary rail break, it is highly likely that a secondary break will occur in the immediate vicinity of the primary break. Thus, where the detection system is provided by a track circuit (a track circuit), it appears as a "gap" or train "loss" in detection.

Track circuits are systems that use two rails as transmission lines. The signal is injected in differential form at one point and received by the receiver at another point. The axle present between these points is converted into a resistance which shorts the two rails, in this way attenuating the received signal. The system thus acts as a detection system which can detect the presence of axles in a given road section very reliably. The latter is defined as the length of the road segment defined by the transmitting and receiving points, respectively.

One known practice is to limit the track circuit by inserting contacts (joints) which are either insulated contacts (mechanical breakpoints) or electrical contacts (no mechanical breakpoints). It is currently the best solution to limit the track circuit with electrical contacts. This is achieved by using a radio frequency signal in the track circuit being tuned. The track is then divided into a plurality of segments, also referred to as "blocking systems", separated by electrical contacts.

According to the state of the art it is customary to use electrical contacts for large sections of track, i.e. between 100 and 2 km.

According to the principles of track circuits, an accidental electrical interruption in a rail will cause the signal at the receiver to disappear, however, in practice this is not always the case: the return of track ground and traction current (traction current) towards the substation (backup) constitutes a parasitic route, enabling the track circuit current to avoid the rail break, thereby impeding its detection.

However, by having the ground point positioned and the back flow of the traction current towards the substation follow several criteria, the detection can be ensured with a certain probability.

Furthermore, to compensate for the self-inductance coils per unit length of track, it is desirable to "boost" the track, that is, place a capacitor at a fixed spacing between the two rails. This makes it possible to achieve a relative increase in power attenuation caused by non- "additive" parasitic routes. The latter technique makes it possible to alleviate these drawbacks, but does not completely eliminate them.

It should be noted that the defects detected using the track circuit depend strongly on external parameters such as the type of earthing, the state of the ballast, the track geometry (catenary or type with third rail, etc.).

Furthermore, these techniques do not make it possible to distinguish between the two types of events of track occupation and rail breakage. In effect, both of these types of events result in a voltage drop in the track circuit. In addition, it is of course important to be able to reliably detect the presence of a train and to distinguish between the two types of information, i.e. rail break and track occupancy.

Furthermore, the solutions proposed in the prior art can only be used in the case of lines in which track circuits with electrical or mechanical contacts are installed, which are not generally used for lines with low traffic volumes or lines with ERTMS (european railway train management system) level-3 signals.

To date, there has been no apparatus for detecting rail breaks for such tracks.

The invention content is as follows:

the object of the present invention is to provide a solution that does not have the drawbacks of the prior art, and to provide a method and a device for reliable detection of rail breakage, in railway engineering terms.

It is therefore an object of the present invention to provide a solution for detecting rail breaks, possibly by using a system comprising detection with track circuits or a system not comprising track circuits.

Another object of the invention is to be able to apply the method and the apparatus of the invention in track sections of considerable length, for example in tens of kilometres, in particular in lines where the track circuit cannot guarantee train detection.

It is a further object of the invention to provide a low cost solution that minimizes the number of devices.

The invention is mainly characterized in that:

according to the present invention there is provided a method for monitoring the integrity of at least one section of railway track formed by two parallel rails between which is provided at one end a signal generator or detector and at the other end an impedance, a detector or signal generator being provided in a common mode line, characterised in that the method comprises the steps of: -generating a signal of a certain frequency by means of said signal generator and injecting the signal into said segment, -searching said signal of said frequency by means of said detector, -performing said segment integrity diagnosis on the basis of the detected signal of said frequency.

According to a first embodiment of the method of the invention:

generating a frequency signal corresponding to the current in the first circuit corresponding to said track section by means of an AC voltage source arranged between the rails,

in an additional circuit consisting of at least one common-mode connection connected to said first circuit, said current of said frequency is picked up and detected by means of a detector arranged in the common-mode line.

According to a second embodiment:

generating a signal of a certain frequency from a current source in an additional circuit, said current source being arranged in a common-mode connection,

the signal of the frequency is picked up and detected in the form of a differential voltage between the two rails in a first circuit corresponding to the track section by means of the detector.

In the method of the invention, the signal may be encoded.

In the method of the invention, the common mode connection may be a ground connection in case the traction current is an AC current. Alternatively, the common mode line may be a connection used as a traction current return to the substation in the case where the traction current is a DC current.

The invention also relates to a device for monitoring the integrity of a section of railway track, preferably for detecting rail breakage, according to a first embodiment, the device comprising at least:

a means for generating a signal disposed between two rails of the railroad track,

an impedance connected between the rails at a predetermined distance from the signal generating means,

means having midpoints, disposed between the rails, and connected by at least a conductor to form a common mode connection,

means for detecting said signal, arranged on said common-mode connection, and

means for processing the signal and performing integrity diagnosis on the segment.

In the device according to the first embodiment, the means for generating a signal may comprise an AC voltage source and the means for detecting the signal may comprise an AC current detector.

The invention also relates to a device for monitoring the integrity of a section of railway track, preferably for detecting rail breakage, according to a second embodiment, the device comprising at least:

a means for detecting a signal disposed between two rails of the railroad track,

an impedance connected between said rails at a predetermined distance from said detection means,

means having midpoints arranged between said rails and at least connected by wires to form a common mode connection,

a means for generating said signal, disposed on said common mode connection,

means for processing the signal and performing integrity diagnosis on the segment.

In the apparatus according to the second embodiment, the means for detecting a signal may comprise an AC voltage detector and the means for generating a signal may comprise an AC current source.

In the device according to the invention, the common mode connection may comprise a ground line passing through a ground point. Alternatively, the common mode connection may comprise a wire that returns the traction current to the substation.

In the apparatus according to the invention, the device having a midpoint may be a coil having a midpoint.

In the apparatus according to the first embodiment, the voltage source may function as a transmitter (Tx) part for detecting a track circuit of a train, and the impedance may function as a tuning unit connected to a receiver (Rx) for detecting a track circuit of a train. The track circuits may be separated from adjacent track circuits by insulated contacts or electrical contacts.

In the apparatus according to the second embodiment, the differential voltage detector may function as a receiver (Rx) part for detecting a track circuit of a train, and the impedance may function as a tuning unit connected to a transmitter (Tx) for detecting a track circuit of a train. The track circuits may be separated from adjacent track circuits by insulated contacts or electrical contacts.

According to the invention, the detection means may comprise an instrument transformer comprising a first coil acting as a primary coil, a second coil acting as a secondary coil, and at least one receiver.

According to one embodiment of the invention, the first coil connects the middle points of the two devices to a middle point belonging to two different tracks (a and B), and the at least one receiver is able to detect a current of a first frequency (F1) corresponding to a first track circuit present on the first track (a) and a current of a second frequency (F2) corresponding to a second track circuit present on the second track (B).

Description of the drawings:

fig. 1a and 1b schematically show the use of a track circuit incorporating an apparatus for detecting rail break in a common mode according to the present invention.

Figures 2a to 2d schematically show four types of apparatus for detecting rail break in accordance with the present invention.

Figure 3 schematically shows a track circuit with its transmitter and its receiver detecting the presence of a train between two electrical contacts.

Fig. 4 schematically shows a track circuit for detecting a train with a device for detecting a rail break according to the invention.

Figure 5 schematically shows a track section comprising two parallel rails equipped with means for detecting rail breakage according to a preferred embodiment of the invention.

The specific implementation mode is as follows:

the invention consists in the presence of a signal generator, in particular a voltage or current source, placed between two rails of a railway track or on a common-mode line, and in the detection of said signal indicative of a rail break or breakage. Any combination of source type (voltage or current) and detector type (measuring current or voltage) is within the scope of the invention.

The term "common mode" is understood to mean a device capable of connecting two rails together. These common mode devices are usually constituted by devices having a midpoint, which are themselves connected to each other by means of a wiring, or the midpoint of which is directly grounded.

Fig. 1 and 2 schematically illustrate the detection principle of the method and apparatus implemented according to a preferred embodiment. As described in more detail with reference to fig. 3.

With this embodiment, according to fig. 1 and 2, a voltage source is provided which is arranged between the two rails, and according to which the presence of a common mode current is detected. Of course, the exact same analysis can be done for the opposite configuration, that is to say if a current source arranged in the common-mode connection is used, and the differential voltage between the two rails is detected.

In the first case, the track circuit is formed by rails 1 and 2, between which an AC voltage source 3 of frequency F1 and an impedance 4 of given impedance at said frequency of the voltage source 3 are arranged.

The current generated by the voltage source is preferably encoded at a frequency which is lower for longer segments.

The method according to the invention preferably uses a coded signal system to distinguish between the traction current and the current used to detect a rail break.

There is also a device 5 (impedance) with a midpoint allowing to ground when it is pulled with an alternating voltage or to return said current to the substation when it is pulled with a direct voltage. These devices make it possible to implement common mode connections.

Such a device 5 has in fact been mounted on a track circuit, thereby being used for the present invention.

In the case of alternating voltage traction current, for example 25kV, 50Hz AC voltage, such a device 5 with a midpoint returns part of the traction current through the conductor 8, leading towards the grounding point 13 (fig. 2 a). A common-mode connection 6 is then present between the two midpoints of the devices 5.

Such means 5 are also present in the case of DC traction currents in order to ensure the rail is insulated from the ground. In this case, the traction current is conducted from the midpoint of the device 5 and the wire 14 to the substation 15 via the wire 8 (fig. 2 b). The electrical path formed by the two conductors 8 and a portion of the conductor 14 represents a common mode connection 6. According to the invention, this connection 6 (fig. 2a or 2b) will be used to detect rail breaks in the track section between the devices 5.

In order to detect the presence of a common mode current, it is preferable to arrange means 7 capable of measuring said current in the connection 6 between the device 5 and the conductor 14 or the grounding point 13, depending on the actual situation.

The device 7 may be constituted by any instrument for measuring electric current known in the art. It is of course configured to distinguish between the passage of traction current and current at frequency F1 for detecting rail break.

Under normal conditions, that is to say no rail break between the source 3 and the impedance 4, a current I passes through the track circuit 10 (fig. 1 a). Due to the inherent asymmetry of the track, a limited part of the current will pass through the wiring 6.

In the case of a rail break 11, the current I will pass through the circuit 12 (fig. 1b), which will result in an increase in the current detected by the device 7 (traction current + current due to common mode). It is therefore sufficient to detect this increase in current and it can be determined that a break has occurred in the rail 1 or 2, thereby detecting a rail break in the section of road concerned.

The adjustment of the detection process should take into account the rail environment (ground, overhang, etc.). The limitation on use depends on the type of traction, on the presence of a ground or return substation, and on the track characteristics.

As shown in fig. 2, the wiring 6 may be formed in various forms depending on the rail characteristics. Essentially two things that can occur are related to the backflow of the traction current (AC or DC). In the case of a 25kV, 50Hz AC traction voltage (fig. 2a), the traction current (at a fixed distance) can be bled off (drain) by means of the grounding point 13 of the track rail, or by the presence of a wire 14 connecting points in the track direction to a transformation substation 15, which in the case of a dc traction voltage is essentially a common rail insulation point at several points on the track (fig. 2 b).

In fact fig. 2a depicts a first embodiment (AC voltage) which makes use of a grounding point 13 connected to the midpoint of the device 5. The device 5 of the invention is preferably an inductive impedance (coil) which exhibits a given magnitude at the frequency F1 of the track circuit, while forming a low impedance at low frequencies. These coils can be used in the method of the invention already in the track in case the device is used as a traction current return path.

Fig. 2b represents a second embodiment in the case of a DC voltage: the conductor 14 essentially discharges the traction current towards the substation 15, but also serves as a connection 6 for carrying out the method according to the invention.

The principle of the invention thus consists in detecting the presence of a common-mode current using the connection, either a ground connection (figure 2a) or a connection redirected to the substation (figure 2 b).

The current between the points is then measured using known methods, for example the mid-point of the coil of the device 5, and a point of the connection 6, for example a ground point or a point on the path that returns the traction current to the substation. The signal detected by the dedicated detector 7 on the connection 6 at the frequency F1 indicates that a rail break has occurred on the section under consideration (track system).

Fig. 2c and 2d show an embodiment in which a current source 40 and a differential voltage detector 41 are placed on the common mode connection 6 between the rails. The system is also able to detect a rail break 11 by detecting the effect of the rail break 11 on the voltage measured by the detector 41.

In accordance with a preferred embodiment, the method of the present invention utilizes existing track circuits, such as track circuits separated by electrical contacts, for locating train positions.

Conventionally, an electrical contact of the type shown in fig. 3 (called RX/TX contact) comprises two tuning units, respectively tu.rx ("tuning unit-receiver") and tu.tx ("tuning unit-transmitter"), which are arranged between two rails 1 and 2, which are connected and are arranged at a distance of 15 to 30 meters from each other. The distance between two adjacent points may vary from a few hundred meters to one or two kilometers. Each joint thus divides the track into two sections 50 and 60 with an overlap area 70, referred to as a "sector system", which corresponds to the distance between the two units. The detection of the presence of a train is achieved by means of an electrical signal at a frequency typical of each sector system present in the circuit corresponding to said sector system, which enables the electrical separation of two adjacent circuits.

Figure 3 shows two electrical contacts which form the track circuit boundary. The left contact cell 20 and the right contact cell 21 are equal in capacitance at the first frequency F1. At this frequency, the AC source (Tx) injects a signal into the track circuit defined by the two junctions. The source Tx is in fact connected in series with the unit 20, while the unit 21 has a parallel receiver Rx which must comprise a device for measuring the current in the track circuit. Since the external units 22 and 23 are equivalent to a short circuit at frequency F1, the track circuit corresponding to the sector system 50 is separated from the adjacent circuit 60. At different frequencies F3, the cell capacitances are different, and in this way the presence of a train in the adjacent sector system 60 can be detected by a current at frequency F3.

For example, the detection of a train on the zone system 50 is due to the axle 24 of the train itself forming a short circuit between the rails 1 and 2. In fact, the axle exhibits a low impedance, which can be seen as a short circuit, which will cause a voltage drop in the receiver connected to the unit 21, deactivating it in this way. This deactivation thus amounts to detecting a train between units 20 and 21.

This situation is very similar to the situation described in fig. 1. By using a device 5 with a midpoint and a common mode connection 6 with a current measuring device 7 it is possible to reliably detect rail breaks in each block system, as shown in fig. 4. The device 5 with the midpoint, which is an inductive impedance, does not necessarily have to be arranged between the tuning units of the electrical contacts.

Also the section of road to be monitored according to the method of the invention may comprise several detection track circuits. This allows the device 5 with the midpoint to be placed near a limited number of contacts in the track direction, rather than near each electrical contact.

It is thus observed that when there is a train on the track circuit 50, current will pass through the axle of the train and not through the wiring 6. As regards the traction current, it is measured by the device 7 when the train passes.

Thus, there is no confusion between the detection of a rail break and the presence of a train on the section of road corresponding to the track circuit 50, provided that the signal is appropriately encoded to distinguish the traction current from the common mode signal used to detect the rail break.

Figure 5 shows a preferred embodiment of the invention. Current measurements are made on two substantially parallel pairs of a and B rails 1, 2 and 1 ', 2'. The two tracks a and B are fitted with track circuits for detecting trains, and the circuits are separated by electrical contacts (20, 22) and (21, 23). In this particular case, the current measuring device 7 is in the form of a gauge transformer (18, 19, 32) capable of detecting rail breakage for one of two block systems (30, 31) belonging to either of the two parallel tracks. Detection of trains in the sector systems 30 and 31 is achieved using differential signals at different frequencies, referred to as F1 and F2. The device 5, 5' with the midpoint is between the tuning elements of the electrical contacts.

In the case of AC voltage, for example, the impedance 18 is a self-inductance coil having a ground midpoint and acts as the primary of the instrument transformer. In the case of DC voltage, the midpoint may be connected to a cable that serves as a connection to the return substation. In this case, the detection of two currents in two circuits of parallel tracks can be realized by means of a single measuring device. If a ground is provided as shown in fig. 5, two coils 18 are used.

At least one dedicated receiver 32 for detecting rail breakage is connected to the secondary coil 19 of the transformer.

Coded track circuit signals are used as it is intended to avoid equating the presence of a train with a fictitious break.

The use of pre-programmed frequency code pairs therefore makes it possible to determine (or more accurately distinguish) the current from the track circuit from the traction current. In response to the determined frequency, the receiver 32 detects (filters) the signal exceeding a certain threshold and performs encoding. This detection may determine that there is an abnormal sector system or track.

It is possible to use one receiver 32 per ground point as long as it is equipped with means (e.g. decoding means) for distinguishing signals of frequency F1 from signals of frequency F2. Preferably, two receivers 32 are mounted per ground point, that is to say one receiver per frequency F1, F2. These receivers will be mounted in parallel on the secondary coil 19.

As shown in fig. 5, rail breaks in one or other of the two block systems 30 and 31 are detected by current measuring means (18, 19, 32). The system of adjacent sectors is monitored by similar means (18 ', 19', 32 ') connected to the inductive connection 5' close to the adjacent points. In fact, the presence of a ground point close to the electrical contact should participate in the common mode conduction associated with rail break in the section. So that it is not necessary to try to detect the signal at an adjacent location.

The current sensors 18, 19 and detector 32 are preferably contained within a housing through which, for example, a wire carrying a common mode current passes. The detection by the detector 32 may be effected at the track or at a distance.

Claims (23)

1. A method for monitoring the integrity of at least one section of railway track (10) consisting of two parallel rails (1, 2) between which a signal generator (3) or detector (41) is arranged at one end and an impedance (4) is arranged at the other end, a detector (7) or signal generator (40) being arranged in a common mode line (6), characterized in that the method comprises the steps of:

generating a signal of a certain frequency by means of said signal generator and injecting the signal into said segment,

searching for said signal of said frequency by means of said detector,

and performing the segment integrity diagnosis according to the detected signals of the frequency.

2. The method of claim 1, wherein:

generating a frequency signal corresponding to the current in a first circuit (10) corresponding to said track section by means of an alternating voltage source (3) arranged between the rails (1, 2),

in an additional circuit (12) consisting of at least one common-mode connection (6) connected to the first circuit, the current of the frequency is picked up and detected by means of a detector (7) arranged in the common-mode connection (6).

3. The method of claim 1, wherein:

generating a signal of a certain frequency from a current source (40) in the additional circuit (12), said current source being arranged in the common-mode connection (6),

-picking up and detecting said signal of said frequency in the form of a differential voltage between the two rails in a first circuit corresponding to said track section (10) by means of said detector (41).

4. The method of claim 1, wherein the signal is encoded.

5. Method according to claim 1, characterized in that the common-mode line (6) is a ground connection in the case of a traction current of alternating current.

6. A method according to claim 1, characterized in that the common-mode line (6) is a connection used as a traction current return to a substation in case the traction current is a direct current.

7. Apparatus for monitoring the integrity of a length of railway track, the apparatus comprising at least:

means for generating a signal, arranged between two rails (1, 2) of said railway track,

an impedance (4) connected between the rails (1, 2) at a predetermined distance from the signal generating means,

a device (5) having a midpoint, which is arranged between the rails (1, 2) and is connected at least at its midpoint by means of a conductor (8) in such a way as to form a common-mode connection (6),

a device (7) for detecting said signal, arranged on said common-mode connection (6), and

means for processing the signal and performing integrity diagnosis on the segment.

8. The apparatus according to claim 7, characterized in that said means for generating a signal comprise an alternating voltage source (3) and said means for detecting said signal comprise an alternating current detector (7).

9. The device according to claim 7, characterized in that the common mode connection (6) comprises a ground line through a ground point (13).

10. An arrangement according to claim 7, characterized in that said common mode connection (6) comprises a conductor (14) for returning a traction current to the substation (15).

11. The apparatus according to claim 7, characterized in that said means (5) with a midpoint is a coil with a midpoint.

12. An arrangement according to claim 7, characterized in that said means for generating a signal comprises an alternating voltage source (3) and said means for detecting said signal comprises an alternating current detector (7), said alternating voltage source (3) functioning as a transmitter (Tx) part of a track circuit for detecting trains, said impedance (4) functioning as a tuning unit (21) connected to a receiver (Rx) for detecting track circuits for trains.

13. An arrangement according to claim 7, characterized in that said means for generating a signal comprises an alternating voltage source (3) and said means for detecting said signal comprises an alternating current detector (7), said alternating voltage source (3) functioning as a transmitter (Tx) part of a track circuit for detecting trains, said impedance (4) functioning as a tuning unit (21) connected to a receiver (Rx) of a track circuit for detecting trains, said track circuit being separated from adjacent track circuits by electrical connections.

14. The apparatus according to claim 7, characterized in that said detection means (7) comprise a meter transformer comprising: a first coil (18) acting as a primary coil, a second coil (19) acting as a secondary coil and at least one receiver (32).

15. The apparatus according to claim 7, characterized in that said detection means (7) comprise a meter transformer comprising: -a first coil (18) acting as a primary coil, -a second coil (19) acting as a secondary coil, and-at least one receiver (32), said first coil (18) connecting the middle point of the two devices (5) to a middle point belonging to two different tracks (a and B), and wherein said at least one receiver (32) is able to detect a current of a first frequency (F1) corresponding to a first track circuit present on the first track (a) and to detect a current of a second frequency (F2) corresponding to a second track circuit present on the second track (B).

16. An apparatus for monitoring the integrity of a length of railway track, the apparatus comprising at least:

means for detecting a signal, arranged between two rails (1, 2) of said railway track,

an impedance (4) connected between said rails (1, 2) at a predetermined distance from said detection means,

a device (5) having a midpoint, arranged between said rails and connected at least at its midpoint by a conductor (8) in such a way as to form a common mode connection (6),

-means (40) for generating said signal, arranged on said common mode connection (6),

means for processing the signal and performing integrity diagnosis on the segment.

17. The apparatus of claim 16, wherein said means for detecting a signal comprises an ac voltage detector and said means for generating a signal comprises an ac current source (40).

18. The device according to claim 16, characterized in that the common mode connection (6) comprises a ground line through a ground point (13).

19. An arrangement according to claim 16, characterized in that said common mode connection (6) comprises a conductor (14) for returning a traction current to the substation (15).

20. An arrangement according to claim 16, characterized in that said means for detecting signals comprises a differential voltage detector (41) and said means for generating signals comprises an alternating current source (40), said differential voltage detector (41) functioning as a receiver (Rx) part for detecting the track circuit of the train, said impedance (4) functioning as a tuning unit (20) connected to a transmitter (Tx) for detecting the track circuit of the train.

21. An arrangement according to claim 16, characterized in that said means for detecting signals comprises a differential voltage detector (41) and said means for generating signals comprises an alternating current source (40), said differential voltage detector (41) functioning as a receiver (Rx) part for detecting a track circuit of a train, said impedance (4) functioning as a tuning unit (20) connected to a transmitter (Tx) for detecting a track circuit of a train, said track circuit being separated from adjacent track circuits by insulated contacts.

22. The apparatus of claim 16, wherein said sensing device comprises a meter transformer comprising: a first coil (18) acting as a primary coil, a second coil (19) acting as a secondary coil and at least one receiver (32).

23. The apparatus of claim 16, wherein said sensing device comprises a meter transformer comprising: -a first coil (18) acting as a primary coil, -a second coil (19) acting as a secondary coil, and-at least one receiver (32), said first coil (18) connecting the middle point of the two devices (5) to a middle point belonging to two different tracks (a and B), and wherein said at least one receiver (32) is able to detect a current of a first frequency (F1) corresponding to a first track circuit present on the first track (a) and to detect a current of a second frequency (F2) corresponding to a second track circuit present on the second track (B).