Patent Publication Number: US-2023160940-A1

Title: Device for detecting breakage of an electrical cable and associated operating method

Description:
RELATED APPLICATION 
     This application claims the benefit of priority from French Patent Application No. 21 12535, filed on Nov. 25, 2021, the entirety of which is incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to an electrical cable anti-theft device and to an associated operating method. 
     The invention belongs to the field of electrical cables and devices for protecting against theft or other unexpected breakage of such cables. 
     BACKGROUND 
     Specifically, sometimes before they are energized, cables or segments of cables are subject to theft or other malicious acts causing them to break, for example when they are stored in trenches, on the ground or at low height, waiting to be installed. 
     These malicious breakages of the cables may also occur after the cables have been installed but before they are energized, in particular if the cables are not buried and are located at easily accessible heights. 
     In order to allow an intervention sufficiently early to stop the cables being stolen, there exist cable anti-theft devices. 
     A device for detecting theft of a lighting cable is known, for example, from document ES-U-1 198 360. A breakage in the cabling of the electrical grid which supplies power to the lighting installation comprising this lighting cable, due to attempted theft of this lighting cable, is detected either during the day, in the absence of lighting, via the detection of the electrical resistance of the cable line concerned, or during the night, via the detection of the electrical intensity of the current passing through the cable. A warning message is then sent in the form of an SMS to a given mobile terminal. 
     Such a device has various limitations. First of all, the monitored cable needs to be energized in order for this anti-theft device, based on the detection of an electrical resistance or of an electrical intensity, to operate. Furthermore, its principle of operation is linked to the nature of the monitored cables, which are lighting cables. It therefore does not apply to all types of cable. 
     Objects and Summary 
     The object of the present invention is to remedy the aforementioned drawbacks of the prior art. 
     To this end, the present invention proposes a device for detecting breakage of at least one electrical cable, this device comprising: 
     the at least one electrical cable,
 
a wireless sensor connected to the at least one electrical cable,
 
at least one power supply unit supplying power to the wireless sensor, the device being noteworthy in that:
 
the at least one power supply unit comprises a means of applying a predetermined potential to the at least one electrical cable; and
 
the wireless sensor is designed to detect either the predetermined potential, which is an indicator of the integrity of the at least one electrical cable, or a floating potential, which is an indicator of the breakage of the at least one electrical cable.
 
     Thus, the breakage of the cable causes the loss of the predetermined potential which was applied to it and the appearance of a floating potential, detected immediately and simply by the wireless sensor. This makes it possible to limit repairs and installation delays in the event that the severed cable was not yet installed, or even production stoppages for users if the cable was already in operation. 
     Moreover, this device is particularly suited to the case of a large number of cables to monitor, in the knowledge that no cabling is required for the installation of a wireless sensor per electrical cable to monitor. This allows tidy and easy installation, in contrast to monitoring devices comprising wire elements that need to be connected. 
     In one particular embodiment, the device further comprises a radiofrequency signal transmitting unit designed to transmit signals which differ depending on whether the detected potential is the predetermined potential or the floating potential. 
     This allows the device to transmit a signal that warns of the effected detection. Thus, upon receiving the warning, any appropriate intervention measure may be taken by the personnel responsible for the electrical cable in question. 
     In this embodiment, the device may further comprise a communication module connected to the wireless sensor and to the radiofrequency signal transmitting unit. 
     Such a communication module is optional. It may be provided as an alternative to a direct data exchange mode between the wireless sensor and the radiofrequency signal transmitting unit. 
     In one particular embodiment in which the device comprises the aforementioned radiofrequency signal transmitting unit, this transmitting unit may be an integral part of the wireless sensor. This makes the device more compact, with fewer components. 
     In one particular embodiment in which the device comprises the aforementioned radiofrequency signal transmitting unit, this radiofrequency signal transmitting unit may comprise at least one antenna. This makes it possible to transmit the signals through the air to a wired or wireless communication network, for example for the transmission of the warning following the detection of breakage of the electrical cable. 
     In one particular embodiment, the device further comprises an energy storage unit supplying energy to the power supply unit. 
     This allows the device to be self-sufficient in terms of energy and to be able to operate even in the absence of a mains power supply in the area where the electrical cable is situated. 
     In this embodiment, according to one particular feature which is optional but not necessary, the device may further comprise a power matching unit connected to the energy storage unit and to the power supply unit and supplying to the power supply unit a power that is matched to the power received from the energy storage unit. 
     This stage of power matching allows compatibility between different types of energy storage units and different types of power supply units. 
     With the same object as that indicated above, the present invention also proposes a method for detecting breakage of at least one electrical cable, this method being noteworthy in that it comprises steps of: 
     applying a predetermined potential to the at least one electrical cable;
 
detecting, by way of a wireless sensor connected to the at least one electrical cable, either the predetermined potential, which is an indicator of the integrity of the at least one electrical cable, or a floating potential, which is an indicator of the breakage of the at least one electrical cable.
 
     In one particular embodiment, the method further comprises a step of sending a warning signal in the event that the aforementioned floating potential is detected. 
     In this embodiment, according to one particular feature which is possible but not necessary, the step of sending the warning signal may comprise a message being sent to a mobile telecommunications terminal, by way of a telecommunications network. 
     Since the particular features and the advantages of the method are similar to those of the device, they are not repeated here. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other aspects and advantages of the invention will become apparent on reading the detailed description below of particular embodiments, which are given by way of entirely non-limiting examples, with reference to the appended drawings, in which: 
         FIG.  1    is a schematic representation of a device for detecting breakage of an electrical cable in accordance with the present invention, in one particular embodiment in which the device comprises two electrical cables; 
         FIG.  2    is a comparative simplified schematic representation of a device in accordance with the present invention in a state in which the cable is whole and in a state in which the cable is severed, in one particular embodiment in which the device comprises a single electrical cable; and 
         FIG.  3    is a flow diagram illustrating steps of a method for detecting breakage of an electrical cable in accordance with the present invention, in one particular embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENT(S) 
       FIG.  1    shows a schematic view of a device  10  for detecting breakage of an electrical cable in accordance with the present invention, in one particular embodiment in which the device  10  comprises two electrical cables  12  to monitor. This particular number of electrical cables  12  is only one example amongst others, any number of cables being possible. 
     The electrical cable  12  considered may for example be an electrical power cable, intended for example to transport energy and/or to transmit data, such as for example a signal cable. 
     By way of a non-limiting example, it may be a cable of several kilometres in length, intended to be buried in a trench, between two stations or sub-stations of an energy supply infrastructure. 
     In addition to this or these cables  12 , the device  10  comprises one or more wireless sensors  14 . 
     The wireless sensors  14  are for example equipped with Bluetooth technology (registered trade mark) or equivalent. 
     Each wireless sensor  14  is connected to an electrical cable  12 . 
     The device  10  furthermore comprises one or more power supply units  18  supplying power to the one or more wireless sensors  14 . 
     In the particular embodiment of  FIG.  1   , the device  10  comprises one power supply unit  18  supplying power to the wireless sensor  14 . Alternatively, a plurality of power supply units  18  may supply power to one and the same wireless sensor  14 . 
     In accordance with the present invention, the power supply unit  18  comprises a means  20  of applying a predetermined potential to the electrical cable  12 , and the wireless sensor  14  is designed to detect either this predetermined potential or a floating potential. 
     Specifically, as shown in  FIG.  1   , the device  10  is connected, via its power supply unit  18  and its wireless sensor  14 , to two conductors of each cable  12  and a short circuit is established at the other end of the cable  12 . 
     The predetermined potential, that is to say a predetermined potential value detected by the means  20  across the terminals of the monitored cable  12 , indicates that the electrical cable  12  to which the wireless sensor  14  is connected is whole, in other words undamaged and notably not severed in order to be stolen. 
     In contrast, the floating potential, that is to say an indeterminate potential value detected by the means  20  across the terminals of the monitored cable  12 , indicates that the electrical cable  12  to which the wireless sensor  14  is connected has been damaged, for example broken. 
     Thus, each wireless sensor  14  is designed to detect either a first predetermined potential, which is an indicator of the integrity of the electrical cable  12  to which it is connected, or a floating potential, which is an indicator of the breakage of this same electrical cable  12 . 
     By way of an entirely non-limiting example, generally, the predetermined potential may be zero, that is to say that an electrical cable  12  monitored by the device  10  may be connected to earth. 
       FIG.  2    illustrates an example of this type, in which the device  10  comprises a single electrical cable  12  which has a zero potential applied to it when it is whole (top diagram in the drawing) and has a floating potential in the case of breakage (bottom diagram in the drawing). 
     As is shown in  FIG.  1   , the device  10  may further comprise one or more optional elements  22 ,  24 ,  26  and  28 , represented by dashes in the drawing and described below. It should be noted that in the embodiment of  FIG.  2   , the device  10  does not comprise any of these optional elements  22 ,  24 ,  26  and  28 . 
     Thus, in one particular embodiment, the device  10  further comprises, optionally, a radiofrequency signal transmitting unit  22  designed to transmit signals which differ depending on whether the detected potential is the predetermined potential or the floating potential. 
     In this particular embodiment, the device  10  may additionally comprise, optionally, a communication module  24  connected to the wireless sensor  14  and to the radiofrequency signal transmitting unit  22 . 
     Alternatively, the radiofrequency signal transmitting unit  22  may be integrated into the wireless sensor  14 . For example, when the wireless sensors  14  are equipped with Bluetooth technology (registered trade mark), a Bluetooth (registered trade mark) gateway may be provided to communicate with all of the wireless sensors  14  and transmit radiofrequency signals through the air to a mobile telecommunications network, for example of the GSM (Global System for Mobile Communications) type. Thus, in the event that breakage of a monitored cable is detected, a warning signal may be sent via the gateway over the GSM network, for example via a text message, to a mobile terminal or to a database. 
     In one particular embodiment in which the device  10  comprises a radiofrequency signal transmitting unit  22 , this radiofrequency signal transmitting unit  22  may comprise one or more antennas designed to transmit these radiofrequency signals through the air to the outside of the device  10 . 
     As illustrated in  FIG.  1   , optionally, the device  10  may also comprise an energy storage unit  26 . It may be for example a battery or cell or any other energy storage means, including of photovoltaic type. 
     The energy storage unit  26  supplies energy to the power supply unit  18 , this allowing the device  10  to operate in the absence of any connection to the mains and of any other energy source near the location of the device  10  and in particular near the location of the one or more cables  12  to monitor. 
     As mentioned above, this is useful when, for example, a length of several kilometres of cable  12  is stored between two stations or sub-stations of an electrical energy supply infrastructure, before being installed and connected to these two stations or sub-stations. 
     In one particular embodiment in which the device  10  comprises such an energy storage unit  26 , still optionally, the device  10  may further comprise a power matching unit  28 . 
     As illustrated in  FIG.  1   , the power matching unit  28  is connected to the energy storage unit  26  and to the power supply unit  18  and supplies to the power supply unit  18  a power that is matched to the power received from the energy storage unit  26 . 
     In this embodiment, the aforementioned means  20  of applying a predetermined potential to the electrical cable  12 , comprised in the power supply unit  18 , supplies this potential to the power matching unit  28 , which applies it to the electrical cable  12  to monitor. When the device  10  comprises no power matching unit  28 , the means  20  applies the potential directly to the electrical cable  12  to monitor. In  FIG.  1   , this is symbolized by arrows between the power supply unit  18 , the power matching unit  28  and the electrical cables  12 . 
     In one embodiment in which the device  10  comprises a radiofrequency signal transmitting unit  22 , a tracking signal may be transmitted by the transmitting unit  22  in the form of a “good condition” message of the monitored electrical cable  12  to a chosen receiving element, such as a fixed or mobile telecommunications terminal, by way of a wired or wireless telecommunications network. 
     By way of an entirely non-limiting example, the network may be a network of GSM type or any other type of communication network. 
     By way of a non-limiting example, the transmission of such a tracking signal can be provided at a certain periodicity, for example once per day. 
     In one embodiment in which the transmitting unit  22  comprises an antenna, the tracking signal is transmitted by the antenna through the air. 
     The flow diagram of  FIG.  3    illustrates steps of a method for detecting breakage of at least one electrical cable  12 . 
     In accordance with the present invention, this method comprises a step E 1  of applying the aforementioned predetermined potential to the electrical cable  12  and a subsequent step E 2  of detecting, by way of the wireless sensor  14  connected to the electrical cable  12 , either the predetermined potential, which is an indicator of the integrity of this electrical cable  12 , or a floating potential, which is an indicator of the breakage of this same electrical cable  12 . 
     Optionally, as illustrated by dashes in  FIG.  3   , the method may further comprise, after step E 2 , a step E 3  of sending a warning signal in the event that the aforementioned floating potential is detected. 
     In one particular embodiment, step E 3  of sending the warning signal may comprise a message being sent to a mobile telecommunications terminal, by way of a telecommunications network. By way of a non-limiting example, the message may be sent in the form of a text message. This sending therefore does not require access to the Internet in the course of the steps of the detection method in accordance with the invention. In contrast, optionally, from a warning message in the form of a text message, a website linked to the aforementioned telecommunications network may, from this text message, send an e-mail to a predefined address. 
     The present invention makes it possible to monitor the integrity of electrical cables remotely and in a way that is simple, effective, inexpensive, and economical in terms of energy and human resources, without it being necessary to modify the manufacturing process of these cables.