EP3317137A1

EP3317137A1 - Monitoring the state of a current collector strip designed to rub against a trolley wire

Info

Publication number: EP3317137A1
Application number: EP16742364.9A
Authority: EP
Inventors: Peter Ovaere
Original assignee: Mersen France Amiens SAS
Current assignee: Mersen France Amiens SAS
Priority date: 2015-06-30
Filing date: 2016-06-30
Publication date: 2018-05-09
Also published as: FR3038269A1; CN108025649A; WO2017001799A1; FR3038269B1

Abstract

A system for monitoring the state of an electric current collector strip (1) designed to rub against a live trolley wire (2), comprises: at least one sensor device (3) designed to be mounted at least partially in the strip so as to extend over only part of the length of the strip, the device being arranged to detect the passage of a trolley wire when the trolley wire is in contact with this part of the strip, at least when the wear height of the strip in this part of the strip has exceeded a threshold value, the sensor device being further arranged to allow measuring at least two different wear heights.

Description

MONITORING THE STATE OF A CURRENT TRANSMISSION STRIP INTENDED TO FRICT AGAINST CATENARY WIRE

The invention relates to the monitoring of the state of an electric power transmission band intended to rub against a catenary wire.

Conventionally, a pantograph system comprises a band made mainly of carbon, or completely made of carbon, and intended to rub against a live catenary wire to supply power to an electrically driven vehicle on which the band is mounted.

The catenary wire is generally installed to form a zigzag along an expected path of travel. The strip extends in a longitudinal direction perpendicular or substantially perpendicular to the direction of instantaneous movement of the vehicle. Due to this zigzag installation, the catenary wire is arranged slightly oblique with respect to this direction of displacement. Thus, the catenary wire is in contact with the strip on a contact zone representing only a portion of the length of the strip, and this zone evolves along the strip when the vehicle on which the pantograph is mounted is driven in motion .

Thanks to this zigzag arrangement, it is thus possible to expect a better distribution of wear than if the contact zone remained substantially the same during the displacement. In other words, the wear profile is more homogeneous than if the catenary wire was substantially rectilinear with respect to a path of displacement.

We seek to qualify the wear to facilitate maintenance.

Conventionally, it is planned to install inside the band a waterproof tube made of metal, carbon or other. This tube is filled with air under pressure. When damage occurs, the tube can break and the consequent pressure decrease can be detected. Following this detection, a pantograph is then lowered to prevent damage to the catenary.

However, this system remains relatively inaccurate in the detection, because there is a risk of rupture too early, for example in case of relatively weak shock or minor damage to the collector band, and / or too late rupture. There is even a risk of failure while the sensor strip is no longer usable, for example, in case of tearing relatively large material.

In addition, this system leads to an immediate deactivation of the pantograph, without it being really possible to predict and organize the maintenance of the tape.

Document JP57-80201 describes a detection system in which an electrical conductor wire is installed in the sensing strip, this conductive wire forming a U whose branches extend longitudinally along the entire length of the strip. When the wear is sufficient, the catenary wire then comes into electrical contact with the wire forming a U, and a detection circuit can detect the current from the catenary wire. The pantograph corresponding to this band is then immediately deactivated.

There is, however, a need for a tape condition monitoring system to track wear as the electrically driven vehicle moves.

It is proposed a system for monitoring the state of an electric power transmission band made mainly or completely of carbon, intended to be mounted on a vehicle with electric drive, and to rub against a catenary wire under tension to power by running this vehicle. The pantograph strip extends in a longitudinal direction and is installed on the electric vehicle such that this direction is perpendicular or substantially perpendicular to a direction of travel of the vehicle. The catenary wire is disposed obliquely with respect to the direction of movement of the vehicle, so that the catenary wire is in electrical contact with the strip on a contact zone representing only a portion of the length of the strip, and which evolves along the belt when the vehicle is driven in motion in the direction of travel. The monitoring system includes:

at least one sensor device intended to be at least partly installed in the strip so as to occupy only a portion of the length of the strip, this device being arranged to detect a catenary passage when the contact zone corresponds to this portion of the strip, at least when the wear height of the strip at level of the band portion has exceeded a threshold. This sensor device is furthermore arranged to make it possible to measure at least two different wear heights.

The portion of band length occupied by a sensor device may for example represent between 0.01% and 20% of the length of the strip, advantageously between 0.1% and 5% of the length of the strip.

The portion of band length occupied by a sensor device may for example correspond to a length of between 0.1 millimeter and 10 centimeters, advantageously between 1 millimeter and

1 centimeter.

Thus, there is provided a point sensor device capable of measuring at least two levels of wear, and capable of detecting moments of catenary passage. This monitoring system makes it possible to track wear, since the sensor device or devices can measure several wear heights. In addition, as the passage of the catenary wire is detected, it is possible to correlate the wear relatively easily with the mileage traveled. Indeed, the catenary son are arranged in zigzag with distances, in the direction of movement, between the relatively regular zigzag extrema. It is thus possible to assume the distance traveled between two detections of passage of the catenary wire, and thus to qualify relatively easily the wear per kilometer traveled.

For example, it is possible to count the moments of passage of catenary between two detections of wear heights in order to qualify the wear per distance traveled.

The measurement of at least two different wear heights can advantageously be made from the signal at the catenary passage detection times, for example from the amplitude of this signal at these times.

By "electrical contact" is meant that current is collected, either because there is contact in the mechanical sense of the term (the strip touches the catenary wire), or because the strip and the catenary wire are sufficiently close at the level of the contact zone so that electric arcs are formed and ensure the transmission of electric current. In an advantageous embodiment, the sensor device may comprise at least one conductive element.

Advantageously, the catenary passage can be detected following the passage of current from the catenary wire in the conductive element. The current from the catenary wire can pass, during the electrical contact with the sensor device, by one or more conductive elements, and this current passage can be detected.

The invention is of course not limited to this type of sensor. For example, it would be possible to have a brightness sensor in a conical orifice of the strip, this brightness sensor making it possible to measure a wear height when the contact zone does not correspond to the orifice, and this brightness sensor being sufficiently sensitive and fast to measure decreases in brightness corresponding to the passage of the catenary wire. This system could thus make it possible to compare the wear of the mileage traveled.

In an advantageous embodiment, the sensor device may comprise at least two conductive elements, each conductive element extending within the band to a band height associated with this conductive element.

Thus, as long as the level of wear has not reached the band height corresponding to a conductive element, no measurement signal comes from this conductive element.

The invention is in no way limited to the use of several conductive elements each having an associated wear height. One could for example provide a relatively resistive element and extending in a direction having a vertical component up to a maximum wear height. The resistance encountered by the electrons coming from the catenary wire is thus a function of the length of the resistive element to be scanned, and therefore of the height of the band at the portion of band corresponding to this sensor device.

In an advantageous embodiment, there is provided a plurality of sensor devices intended to be at least partly installed on the same strip so that the strip length portions corresponding to this plurality of sensor devices are separate from each other . In other words, the sensor devices can be distributed along the strip. The wear monitoring can thus be more accurate and in addition, one can better estimate the homogeneity of wear along the strip.

This system can thus be relatively accurate, even in turn-like or tunnel-like road portions, in which the catenary wire is capable of moving relative to the web in a range corresponding only to the length of the web. the band.

Of course, the invention is in no way limited to this embodiment, and it could for example provide a system with a single sensor device installed for example in the middle of the band.

Advantageously and without limitation, the conductive elements may be made mainly or completely of copper.

Advantageously and without limitation, the elements of the same sensor device can be separated from each other by an insulator, for example ceramic or glass fibers.

Advantageously and in a nonlimiting manner, each conductive element may be sheet-shaped.

The sensor device may advantageously be installed so that at least one conductive sheet, and preferably each conductive sheet is disposed in a plane having a normal vector substantially in the direction of travel.

Advantageously and without limitation, at least one sensor device may comprise a stack of sheets separated two by two by the insulator. This stack may advantageously be embedded in a resin.

Advantageously and in a nonlimiting manner, in the case of several sensor devices, it will be possible to connect at least two sensor devices, and preferably all the sensor devices, to a single cable, thus making it possible to reduce the space requirement. 'an electrical monitoring circuit.

In an advantageous embodiment, the monitoring system may comprise:

an electrical measuring circuit, comprising a first transformer winding and a generator capable of delivering an alternating current, the electric measuring circuit being arranged to at least a part of the current delivered by the generator passes through this first winding,

an electrical detection circuit, this circuit comprising a second transformer winding, a reference branch of the electrical potential of the detection circuit, this branch being designed to be in contact with the strip or with weakly resistive conducting means in contact with the band, so that the ground voltage of the detection circuit is equal to or very close to the voltage of the catenary wire when in contact with the band, and this at least one sensor device,

a transformer comprising the first and second windings, for isolating the electrical circuit for measuring the ground voltage of the detection electric circuit, and

means for measuring the voltage at the terminals of the first winding and / or the intensity crossing this first winding.

Thus, the voltages in the detection circuit can be relatively high and variable with respect to the earth, since the mass of this circuit is connected to the band. For example, the catenary wire can be traversed by a signal of 25000 volts AC at 50 Hz, or even 1500 V DC. Thus, in the event of additional electrical contact between a part of the detection circuit and the strip, for example following a rupture of a wire of the circuit, no overvoltage is transmitted since this additional contact is electrically equivalent to a ground connection. of the detection circuit.

By "weakly resistive conducting means" and "equal or very close" is meant here one (or more) conductive element, for example a stirrup, opposing a sufficiently weak resistance between the reference arm and the band so that the mass voltage the detection circuit does not deviate more than 5% of the tension of the strip, preferably no more than 2% of the tension of the strip.

The signal injected by the generator may have a relatively low peak voltage with respect to this supply voltage, for example 3 volts or 5 volts.

The electrical measuring circuit may have a floating mass, or not, for example a mass connected to the chassis of a railroad vehicle or to the earth. The passage of the catenary and the wear of the strip may have an impact on the detection circuit, via the one or more sensor devices, and thus on the voltage collected across the measuring circuit-side winding.

The detection circuit may advantageously comprise other detection elements, sensitive to the state of the band, that the measurement device (s).

For example, the detection circuit may further comprise an electrically insulated wire, intended to be installed along the tape, for example within the tape or on a surface of the tape. In the event of cracking or breaking of the tape, this wire is likely to break, thus affecting the transmission of the generated alternating signal and therefore the voltages across the windings of the transformer.

For example, if this wire is mounted in parallel with a resistor, in the event of wire breakage, the equivalent resistance increases, and the voltage across the first winding decreases. It is thus possible to detect the breakage of this wire by analyzing the signal measured at the terminals of this winding.

In one embodiment, the detection circuit may comprise at least one additional insulated wire intended to be installed along the strip, for example inside the strip or on one surface of the strip, mounted in parallel with the strip. insulated wire and having mechanical strength properties different from that of the insulated wire. In particular, the breaking strength may be different from one insulated wire to another.

By virtue of this arrangement of a plurality of insulated wires in parallel, these wires having different mechanical strength properties from one wire to another, it is possible to detect a cracking of the band before the breaking of the band. Indeed, in case of cracking, it can be expected that the most fragile wire breaks first, which causes a change in the equivalent resistance and therefore the signal measured across the transformer.

It is possible to leave the pantograph in place as long as at least one insulated wire is still intact, or as long as the mechanically strongest insulated wire is still intact, thus avoiding the inconveniences associated with an unexpected lowering of the pantograph, as in the prior art. Each insulated wire may comprise a conductive core and an insulating sheath.

The conductive core may have a linear resistance sufficiently high that the equivalent resistance variation can be detected. Alternatively, it may be provided to mount each insulating wire in series with a corresponding resistor, to allow the detection of the breakage of the wire. Alternatively, particularly when the circuit comprises a single insulated wire whose break is detected by a zero crossing of the signal at the terminals of the first winding, the core of the wire may have a low linear resistance and it is possible to refrain from mounting resistance in series with this insulated wire.

Advantageously and in a nonlimiting manner, the detection circuit may be arranged so that one or more outputs of the at least one sensor device and the at least one insulated wire are connected (or, in case of contact with the catenary wire, connectable) to the strip or to weakly resistive conductive means in contact with the strip. It is thus forbidden to provide an output wire connecting the output (s) of these detection elements to the ground of the detection circuit. In other words, rather than a closed loop, there is provided a detection circuit with an end which is, at least part of the time of use, in contact with the band or with weakly resistive conductive means in contact with the band. The installation can thus be simpler, and it also limits the risk of inversion son.

Advantageously, when several detection elements are provided, these elements can be mounted in parallel with each other or with one or more resistive elements. If one of these detection elements connected in parallel is faulty or destroyed due to the state of the band, it will nevertheless be possible to measure a signal between the terminals of the first winding. It will be possible to provide a warning signal, alarm type, rather than immediately driving a lowering of the pantograph.

Advantageously, when such a parallel connection is provided, the at least one branching node between the second winding and the detection elements can be in or on the strip. In other words, the detection circuit may comprise a single input wire between the second bearing and the band. The second winding can be connected to the sensing element (s) by a wire threshold penetrating into or mounted on the band.

When, moreover, the output or outputs of the detection elements are connected (or connectable via the catenary wire) to the band or to weakly conductive means in contact with the band, the detection circuit may comprise a single wire penetrating into the band. .

More generally, a single input wire penetrating into or mounted on the tape may connect the second winding to the sensing element (s), and each sensing element may include an output connected to the tape or connectable to the tape. in case of contact with the catenary wire.

Advantageously, this at least one insulated wire and this at least one sensor device can be connected in series or bypass from a single input wire for connection to the second winding. Thus, from the signal between the terminals of the first winding is extracted both information as to cracking or breaking and information as to wear.

Advantageously, the monitoring system may further comprise processing means in communication with this at least one sensor device, these processing means, for example all or part of one or more processors, being arranged to identify from at least one signal received from the at least one sensor device two consecutive catenary passage times, to associate the duration between these instants a predetermined distance and, when at least two wear heights have been reached, estimate from of this at least one signal received a wear of the band per kilometer traveled.

There is further provided a pantograph assembly comprising a monitoring system as described above, as well as the current transmission band. The monitoring system can be installed on the tape.

There is further provided an electrically driven vehicle comprising a pantograph assembly as described above, for example a railroad tractor, or the like.

It is furthermore proposed a method of monitoring the state of an electrical current transmission band made mainly or completely of carbon, extending in a longitudinal direction, mounted on a vehicle with electrical drive of so that this longitudinal direction is perpendicular or substantially perpendicular to a direction of movement of the vehicle, and intended to rub against a catenary wire under tension to supply power to the vehicle, the catenary wire being disposed obliquely to the direction of travel of the vehicle, so that the catenary wire is in electrical contact with the strip on a contact zone representing only a portion of the length of the strip, and which evolves along the strip when the vehicle is driven in motion according to the displacement direction, the method comprising:

receiving at least one signal, and preferably a single signal, of at least one sensor device at least partly installed in the strip so as to occupy only a portion of the length of the strip, this device being arranged to detect a catenary passage when the contact area corresponds to this portion of the strip, at least when the wear height of the strip at the portion of the strip has exceeded a threshold, and this sensor device is further arranged to be able to measure at least two different wear heights.

The method may advantageously comprise a processing step during which a predetermined distance is associated with two consecutive catenary passage signal times, and during which it is estimated from the at least two measurements of height made a wear of the band per kilometer traveled.

The method may also comprise a development step, according to this estimate, and transmission to control means of the pantograph of a message to control the lowering of the pantograph.

This method may for example be implemented by a processing device of the processor type, for example a microcontroller, a microprocessor, a DSP (Digital Signal Processing), or other.

It is thus proposed a processing device comprising receiving means for performing the reception step described above, for example an input port, an input pin or the like, and processing means for carrying out the operation. estimation step described above, for example, a processor core or the like, and means transmission, for example an output port, an output pin, or the like, for transmitting the developed signal to control means of the pantograph, for example a stepper motor.

There is further provided a computer program product comprising instructions for performing the steps of the method as described above when said instructions are executed by a processor.

The invention will be better described with reference to the figures below, which represent embodiments given by way of example and not limiting.

Figure 1 schematically shows a monitoring system according to one embodiment of the invention, when installed in a sensor strip in contact with a catenary wire.

Figure 2 shows in more detail an example of a sensor device for the monitoring system schematically shown in Figure 1.

Figure 3 is a top view schematically showing an example of a sensor device of the monitoring system of Figures 1 and 2, when installed on a partially shown band, and in contact with a catenary wire also partially shown.

FIG. 4 schematically represents an example of a monitoring system according to one embodiment of the invention.

Figure 5 shows schematically an example of a monitoring system according to another embodiment of the invention.

FIG. 6 is a graph showing an example of the appearance of a voltage signal measured at the terminals of a first winding of a transformer of a surveillance system according to one embodiment of the invention.

Fig. 7 is a flow chart for illustrating an exemplary method according to an embodiment of the invention.

Identical references can be used from one figure to another to designate identical or similar elements.

With reference to FIG. 1, a band 1 made mainly or completely of carbon extends in a longitudinal direction corresponding here to the vector x. This carbon band is transverse with respect to a direction of movement of the electric traction vehicle on which this band is mounted, this direction of displacement corresponding to the vector y.

In the present description, the terms front, rear, refer to the front and rear directions of the vehicle on which is mounted the monitoring system described. The vertical direction can be the direction of the gravity vector. The axes x, y, z correspond respectively to the longitudinal direction of the capture band, the direction of movement of the vehicle, and the vertical direction. In the figures, the monitoring system is installed on a powerplant installed on a flat and horizontal ground, and at a location without turning, that is to say that it is assumed that the capture strip extends longitudinally following normal vertical direction and direction of travel. Of course, in reality, the longitudinal direction attached to the capture band, the direction of movement may not be quite normal between them and the plane defined by these two directions may not be perfectly horizontal.

The strip 1 is disposed under a high voltage catenary wire 2 (for example 1500 V or 25000V), and when the vehicle is moving, the strip 1 can be in contact with the catenary wire 2, in order to collect the electric current necessary to pull the vehicle.

The catenary wire 2 is generally arranged zigzag along the expected path for the vehicle, that is to say that when the vehicle is moved in the y direction, the catenary wire 2 performs a scan relative to the strip 1, in the direction x. The strip 1 is thus traversed longitudinally by the catenary wire 2, which allows a better distribution of the wear of the strip.

The monitoring system of this embodiment comprises a plurality of sensor devices 3, each sensor device occupying a relatively small portion of the length of the strip 1. For example, the strip 1 may extend in the x direction on nearly one meter, while each sensor device 3 may have a diameter of a few millimeters, for example 3 millimeters.

It can be noted that the figures are schematic, and that the scale is a priori not respected. The sensor devices 3 are arranged at different locations along the belt 1, so that when the vehicle is driven in motion, these sensor devices are intended to be in contact with the catenary wire 2 one after the other .

Each sensor device 3 comprises conductive elements referenced 5, 6, 7, 8, 9 in FIG.

When the catenary wire 2 is in contact with a conductive element, current from this catenary wire passes into this conductive element. The conductive element is connected via a cable 4 to a processing device, local or remote, and the electrical signal from the catenary wire 2 can thus be detected by this processing device, thus making it possible to detect the passage of the catenary wire at the corresponding sensor device. As further explained with reference to Figures 4 and 5, the cable 4 is part of an electrical detection circuit having its mass voltage equal to the voltage of the strip. In operation, the strip is in contact with the wire 2, so that the ground voltage of the detection circuit is the voltage of the catenary wire 2.

A contact between the catenary wire 2 and a conductive element among the elements 5, 6, 7, 8, 9, is equivalent to a grounding of this conductive element, which modifies the equivalent resistance of the detection circuit.

Referring to Figures 2 and 3, each sensor device 3 comprises a plurality of conductive elements 5, here made of copper and leaf form extending substantially in the plane normal to the y direction.

Each of these copper sheets 5, 6, 7, 8, 9 is connected to a corresponding resistor 15, 16, 17, 18, 19, also connected to the cable 4.

Thus, if the level of wear of the strip is such that for example the sheets 5 and 6 are, during the passage of catenary wire, in contact with this catenary wire, and such that the strips 7, 8, 9 remain isolated from the catenary wire during the passage of this wire, the electrical signal received during the passage of catenary wire will have a value depending on the resistance values 15 and 16.

Resistors 15, 16, 17, 18, 19 may have different values, or not. The electrical signal measured during the passage of catenary, is a function of the effective wear height. Thus, the electrical signal on the cable 4 may have the shape of a set of peaks, each peak corresponding to the passage of the catenary wire on a sensor device, and the amplitude of the peaks being representative of the level of wear .

By associating the time interval between two peaks at a predetermined distance, a function of the zigzagging of the catenary wire, and a function of the band gap between two adjacent sensor devices, the wear can be correlated with mileage traveled.

With reference to FIG. 3, the sensor device 3 may have a diameter of the order of a few millimeters, and a height corresponding, for example, to 50-90% of the height of the strip when new, for example included between a few millimeters and a few centimeters.

The catenary wire may have a diameter of the order of a centimeter, that is to say that the contact area may extend in the x direction for a few millimeters, for example 2 or 3 mm.

The carbon band 1 may have a width in the y direction, for example between 35 and 60 millimeters.

The copper sheets 5, 6, 7, 8 9 may be insulated from each other by a ceramic material, and the stack comprising these copper sheets and the ceramic may be embedded in a resin, the resin assembly plus stack having and a section of diameter of about 3 millimeters.

Returning to FIG. 2, the connection between the copper foils 5,

6, 7, 8, 9 and the corresponding resistors 15, 16, 17, 18, 19 can be performed by brazing at a relatively high temperature.

The invention is not limited to a predetermined number of sensor devices. One could for example provide one, two, three, four, five, ten sensor devices, or other.

The invention is also not limited by the number of copper foils in a sensor device. In this example, five conductive elements 5, 6, 7, 8, 9 are provided, thus making it possible to measure five different wear heights.

With reference to FIG. 4, a monitoring system 40 comprises an isolation transformer 50 comprising a first winding 31 and a second winding 22. The system 40 comprises an electric detection circuit 20 and an electric measuring circuit 30.

The detection circuit comprises a reference branch 23 in contact with the band 1, that is to say that the ground of the circuit 20 is at the potential of the band, and therefore of the catenary wire as long as there is contact between the band 1 and the wire 2. Alternatively, the reference branch 23 could be welded to a stirrup not shown.

A generator 2 1 makes it possible to inject a current into this detection circuit 20. This current may vary sinusoidally, with a peak amplitude of for example a few milliamps, and a frequency of, for example, several kHz, for example 4 kHz. The generator 2 1 and the first winding 31 are arranged in series, so that the first winding 31 is traversed by the generated current.

The transformer 50 makes it possible to isolate the measuring circuit 30 from the ground voltage of the detection circuit 20.

In this example, the detection circuit 20 comprises two detection elements connected in parallel, namely a set of sensor devices 3 for measuring the wear of the strip 2, and an insulated wire 25 bonded to the strip.

The insulated wire 25 has a wire resistance Rm, due to the linear resistance of a conductive core of this sheathed wire 25.

The sensor devices 3 are each similar to that described with reference to FIGS. 1 to 3.

This set of sensors 3 is connected in parallel with a resistor

R3. In case of contact between the catenary wire and one or more conductive elements (s) of a sensor 3, the ends of this or these conductive elements are at the same potential as an end node 27 in contact with the strip 2 If the contact between the catenary wire and these one or more conductive element (s) of the sensor 3, is effected via an electric arc, these ends are substantially at the same potential as the node 27. Current flows between these ends and a branching node 26 with the resistor R3, meeting a resistance Rh function of the number of conductive elements in electrical contact with the catenary wire 2. The current injected by the generator 2 1 then meets a resistance equal to the resistance Rm plus the equivalent resistance to the parallel mounting of the resistors R3 and Rh.

When the catenary wire is no longer in contact with any sensor device, the resistance opposed by the detection circuit to the passage of the current is then simply equal to the sum Rm + R3.

The insulated wire 25 is relatively fragile, and therefore liable to break in the event of web breakage. No current then passes into the detection circuit and the signal measured across the winding 31 goes to zero. In case of contact between a broken end of the wire 25 and the band, the resistance encountered becomes quite low, depending on the length of wire corresponding to this end, and we can also detect the rupture of the band.

In case of wire break detection 25, a control signal is generated so as to control the lowering of the pantograph.

The measuring circuit comprises a resistor R32 connected in series with the generator 2 1, and a processor 33 for receiving a signal proportional to the signal across the winding 31.

In the embodiment of Figure 5, one of the terminals of the winding 22 is in electrical contact with a current collection bracket (not shown), installed under the strip. A reference branch 23 between this terminal and the stirrup is thus connected to a non-resistive conductive element in contact with the band.

In addition, in this embodiment, not only one insulated wire 25, but two wires 25, 25 'with different mechanical strength properties are provided. For example, the wire 25 'has a lower breaking strength than that of the sheathed wire 25. This wire 25 can thus be broken while the wire 25 is still intact, thereby detecting cracking before breaking the strip.

In an alternative embodiment and not shown, it could provide more than two insulated son, for example three, four or five insulated son, connected in parallel and having different tensile strengths from one wire to another. This can detect tape cracking in a gradual manner.

A node 28 provides bypassing the insulated wires 25, 25 ', and also a set of sensor devices 3 similar to the set described above. Figure 6 shows a theoretical example of the type of curve that could be recorded by a processor 33 during the life of a carbon band. The abscissa corresponds to time and the ordinate to tensions.

The peaks of this curve correspond to moments of passage of catenary.

More precisely, at instant t, the catenary wire does not touch any wear sensor 3. The equivalent resistance of the detection circuit is therefore equal to the sum of the resistor R3 and the equivalent resistance to parallel mounting of the insulated wires. .

At the moment I2, the catenary wire touches a wear sensor 3, the wear depth being relatively low at the wear sensor in contact with the catenary wire 2. The equivalent resistance of the detection circuit is therefore equal to the sum of the resistance R3 and the equivalent resistance to the parallel mounting of the insulated wires and this wear sensor. The equivalent resistance is therefore lower than at the instant ti, and the recorded voltage is therefore higher than at this moment

The moment Î3 corresponds to a moment of passage of catenary at a sensor 3, at which the depth of wear is relatively high. The resistance opposed by this wear sensor is therefore lower than that opposed by the sensor in contact with the catenary wire at time θ2. The peak corresponding to this moment Î3 is therefore higher in amplitude than that corresponding to the instant Î2. This device thus makes it possible to ensure the homogeneity of the wear, or at least to have an idea of the wear profile during the operation of the strip.

The moment U corresponds to a break of the most fragile wire 25 '. The equivalent resistance of the circuit increases accordingly, and the measured voltage drops sharply.

However, peaks continue to be recorded during the passage times of the catenary wire at the level of the sensors 3, for example at the instant ts.

The instant corresponds to a breaking of the most solid wire 25. The voltage drops to zero. A pantograph lowering control signal is output, which prevents recording further peaks thereafter. FIG. 7 is a logic diagram for illustrating an exemplary method implemented in the processor referenced 33 in FIGS. 4 and 5.

During a step 101, a voltage signal U (t) is received from which an equivalent resistance value of the detection circuit is estimated during a step not shown.

During a step 102, a value of wear parameter S _w and a break parameter value Sb are deduced from this equivalent resistance value. In this example, we use a Boolean variable for this parameter Sb.

In this step 102, it is also possible to calculate a wear value per kilometer traveled S _w -km (not shown), as a function of the moments corresponding to peak maxima and as a function of the amplitudes of the peaks.

During a test step 103, it is ensured that the wear has not exceeded an acceptable threshold THR and that the band is not broken. It can also be ensured that the value of wear per kilometer traveled does not exceed a threshold THR 'not shown.

If necessary, during a step 104, an SCONTROL signal is generated, allowing contact between the strip and the catenary wire. Then the processor goes into a standby state during a step 106, before receiving a new voltage value.

If it turns out after the test 103 that the wear has exceeded the threshold THR, that the wear per kilometer traveled is too high or that the band is broken, then the signal SCONTROL takes a value, for example equal to

1, to impose the lowering of the pantograph.

Claims

claims

A system for monitoring the condition of an electric power transmission band (1) made primarily or completely of carbon, extending in a longitudinal direction, to be mounted on an electrically driven vehicle so that longitudinal direction is perpendicular or substantially perpendicular to a direction of movement of the vehicle, and intended to rub against a catenary wire (2) under voltage to supply power to the vehicle, the catenary wire being disposed obliquely to the direction of travel of the vehicle, so that the catenary wire is in electrical contact with the strip on a contact zone representing only a portion of the length of the strip, and which evolves along the strip when the vehicle is driven in motion according to the direction of movement, the monitoring system comprising:

at least one sensor device (3) intended to be at least partly installed in the strip so as to occupy only a portion of the length of the strip, this device being arranged to detect a catenary passage when the contact zone corresponds at this portion of the strip, at least when the wear height of the strip at the portion of the strip has exceeded a threshold, and this sensor device is further arranged to be able to measure at least two wear heights different.

The monitoring system of claim 1, wherein the sensor device comprises at least one conductive element (5, 6, 7, 8, 9), and

the catenary passage can be detected following the passage of current from the catenary wire (2) in the conductive element.

The monitoring system of claim 2, wherein the sensor device comprises a plurality of conductive elements (5, 6, 7, 8, 9), each conductive element extending within the band to a height band associated with this conductive element.

4. Monitoring system according to claim 3, wherein for the conductive elements are made of copper, in sheet form, and the sensor device comprises a stack of conductive elements separated from each other by an insulator and embedded in a resin .

A monitoring system as claimed in any one of claims 1 to 4, comprising a plurality of sensor devices for installation on the same band, such that the length portions of the band corresponding to this plurality of sensor devices are distinct from each other.

The monitoring system according to any of claims 1 to 5, comprising:

an electrical measuring circuit (30), comprising a first transformer winding (31) and a generator (21) capable of delivering an alternating current, the electrical measuring circuit being arranged so that at least a portion of the current delivered by the generator passes through this first winding,

an electrical detection circuit (20), this circuit comprising a second transformer winding, a reference branch of the electrical potential of the detection circuit, this branch being designed to be in contact with the strip or with weakly resistive conductive means, contact with the strip, so that the ground voltage of the detection circuit is equal to or very close to the voltage of the catenary wire when in contact with the strip, and said at least one sensor device,

a transformer (50) comprising the first and second windings, for isolating the electrical circuit for measuring the ground voltage of the detection electric circuit, and

measuring means (33) for measuring the voltage at the terminals of the first winding and / or the intensity crossing this first winding.

The monitoring system of any one of claims 1 to 6, further comprising: at least one electrically insulated wire (25), intended to be installed along the band, and capable of being broken in the event of cracking or breaking of the band.

8. pantograph assembly comprising a monitoring system according to any one of claims 1 to 7, as well as the current transmission band.

9. A method of monitoring the state of an electric power transmission band made mainly or completely of carbon, extending in a longitudinal direction, mounted on an electrically driven vehicle so that this longitudinal direction is perpendicular or substantially perpendicular to a direction of movement of the vehicle, and intended to rub against a catenary wire under voltage to supply power to the vehicle, the catenary wire being disposed obliquely to the direction of movement of the vehicle, so that the wire of catenary is in electrical contact with the strip on a contact zone representing only a portion of the length of the strip, and which evolves along the strip when the vehicle is driven in movement in the direction of movement, the monitoring method comprising :

receiving at least one signal from at least one sensor device at least partly installed in the strip so as to occupy only a portion of the length of the strip, this device being arranged to detect a catenary passage when the contact zone corresponds to this portion of the strip, at least when the wear height of the strip at the portion of the strip has exceeded a threshold, and this sensor device being furthermore arranged to make it possible to measure at least two wear heights different.

The method according to claim 9, further comprising a processing step in which two consecutive catenary passage signal times are associated with a predetermined distance, and in which it is estimated from at least two measurements of height made wear of the band per kilometer traveled.