Energy Harvesting System for Harvesting Electric Energy from a Power Cable and an Illuminating System for Illuminating Said Power Cable Using the Electric Energy Harvested by the Energy Harvesting System

Abstract

Energy harvesting system for harvesting electric energy from a power cable including a power cable having at least one core that includes in a radial direction: an electric conductor; an insulation system surrounding the electric conductor comprising at least an insulating layer; a ground shield surrounding the insulation system; and at least one insulated metallic electrode positioned between the electric conductor and the ground shield. At least a part of an outer surface of the at least one insulated metallic electrode is not in direct contact with the ground shield. The at least one insulated metallic electrode is spaced from the electric conductor.

Claims

1. An energy harvesting system for harvesting electric energy from a power cable, the system comprising a power cable comprising at least one core that comprises in a radial direction: an electric conductor; an insulation system surrounding the electric conductor, the insulation system comprising an insulating layer; a ground shield surrounding the insulation system; and at least one insulated metallic electrode positioned between the electric conductor and the ground shield, wherein at least a part of an outer surface of the at least one insulated metallic electrode is not in direct contact with the ground shield, and wherein the at least one insulated metallic electrode is spaced from the electric conductor.

2. The energy harvesting system according to claim 1, wherein the ground shield comprises a semiconductive layer.

3. The energy harvesting system according to claim 1, wherein the at least one insulated metallic electrode is made in form of a metallic strip describing an arc substantially coaxial with respect to the at least one core.

4. The energy harvesting system according to claim 1, wherein the at least one insulated metallic electrode is made in form of metallic wires arranged along a circumference substantially coaxial with respect to the at least one core.

5. The energy harvesting system according to claim 1, wherein the at least one insulated metallic electrode is made in form of a metallic ring substantially coaxial with respect to the at least one core.

6. The energy harvesting system according to claim 1, wherein the at least one insulated metallic electrode comprises an electrode insulating layer, that covers at least partially the metallic outer surface of the at least one insulated metallic electrode.

7. The energy harvesting system according to claim 6, wherein the electrode insulating layer is made by enamel, or by a tape or by extruded polymer.

8. The energy harvesting system according to claim 1, wherein the at least one insulated metallic electrode is in direct contact with the insulating layer.

9. The energy harvesting system according to claim 2, wherein the at least one insulated metallic electrode is in direct contact with the semiconductive layer of the ground shield.

10. The energy harvesting system according to claim 1, further comprising electrical connectors connected to the insulated metallic electrode and to the ground shield respectively, wherein the connectors are arranged to be connected to further electrical terminals.

11. An illuminating system for illuminating an electric power cable comprising: an energy harvesting system for harvesting electric energy from a power cable, the system comprising a power cable comprising at least one core that comprises in a radial direction: an electric conductor, an insulation system surrounding the electric conductor comprising at least an insulating layer, a ground shield surrounding the insulation system, and at least one insulated metallic electrode positioned between the electric conductor and the ground shield, wherein at least a part of an outer surface of the at least one insulated metallic electrode is not in direct contact with the ground shield and wherein the at least one insulated metallic electrode is spaced from the electric conductor; and at least one system of lighting sources coupled to an outer surface of a respective core or to an outer surface of the power cable and having a first ground terminal directly or indirectly electrically connected to the ground shield and a second terminal directly or undirectly electrically connected to the at least one insulated metallic electrode of a respective core.

12. The illuminating system according to claim 11, further comprising at least one safety and/or conditioner device having two input terminals electrically connected to the ground shield and to the at least one insulated metallic electrode respectively and two output terminals electrically connected to the first ground terminal and to the second terminal of the system of lighting sources respectively, wherein the at least one safety and/or conditioner device is configured for protecting the system of lighting sources against over-currents and/or over-voltages and/or the at least one safety and/or conditioner device is configured for rectifying the voltage across the input terminals.

13. The illuminating system according to claim 12, wherein the at least one safety and/or conditioner device is mounted at one respective end of the power cable.

14. The illuminating system according to claim 12, further comprising a plurality of the safety and/or conditioner device mounted along the power cable at predefined lengths.

15. The illuminating system according to claim 11, wherein the system of lighting sources comprises a LED strip wound on the outer surface of the respective core.

16. The illuminating system according to claim 11, wherein the system of lighting sources comprises an electroluminescent tape wound on the outer surface of the respective core.

17. The illuminating system according to claim 12, wherein the power cable is provided at least at one end with a terminal connector comprising a case inside which electrical contacts are provided, and wherein the at least one safety and/or conditioner device is housed in a box mounted inside the case of the terminal connector.

18. The illuminating system according to claim 17, wherein the box is fixed to a wall of the case.

19. A power cable comprising: an electric conductor; an insulation layer surrounding, along a radial direction, the electric conductor in a radial direction; a ground shield surrounding, along the radial direction, the insulation layer; and an insulated metallic electrode positioned between the electric conductor and the ground shield, wherein a part of an outer surface of the insulated metallic electrode is not in direct contact with the ground shield, wherein the insulated metallic electrode is spaced from the electric conductor, and wherein the power cable is part of an energy harvesting system for harvesting electric energy from the power cable.

20. The power cable according to claim 19, wherein the ground shield comprises a semiconductive layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Further characteristics will be apparent from the detailed description given hereinafter with reference to the accompanying drawings, in which:

[0043] FIGS. 1A, 1B, 1C, 1D are four schematic cross-sectioned views of an energy harvesting system according to four embodiments of the present disclosure;

[0044] FIGS. 2A, 2B, 2C, 2D, 2E, 2F are six schematic views of an illuminating system according to five embodiments of the present disclosure; and

[0045] FIG. 3 is a schematic perspective view of a terminal connector provided at the end of a power cable included in an embodiment of the illuminating system according to the present disclosure; FIG. 3 shows also a detail enlarged view of a box housed in the terminal connector.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0046] With reference to the enclosed figures, an energy harvesting system 10 according to the present disclosure is schematically represented.

[0047] The energy harvesting system 10 comprises a power cable 20 comprising at least one core 21. For example the power cable can be a three-phase power cable with three cores or a single-phase with one core.

[0048] In any case, the at least one core 21 comprises in a radial direction an electric conductor 22, an insulation system surrounding the electric conductor 22 and a ground shield 23, 25 surrounding the insulation system.

[0049] In different embodiments, the ground shield 23, 25 comprises a first semiconductive layer 25 surrounding the insulating system. In some of the embodiments, the ground shield 23, 25 comprises also a metallic sheath, for example made by copper or aluminum, surrounding the first semiconductive layer 25.

[0050] The insulation system comprises at least an insulating layer 24.

[0051] The insulation system can comprise also a second inner semiconductive layer 26 surrounding the electric conductor 22 and surrounded by the insulating layer 24.

[0052] For example, the insulating layer 24 can be made of cross-linked EPR (ethylene propylene rubber), or of EPR (ethylene propylene rubber), or of XLPE (crosslinked polyethylene), or of PVC (Polyvinyl Chloride),PE (Polyethylene), or of ECTFE (ethylene chlorotrifluoroethylene), or of PVDF (Polyvinylidene fluoride), or of Nylon.

[0053] For example the semiconductive layers 25, 26 can be made of thermoplastic polymer chosen from one of the following: low density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium density polyethylene (MDPE), and ethylene vinyl acetate (EVA).

[0054] According to the present disclosure, the at least one core 21 comprises also at least one insulated metallic electrode 27, 28, 29 positioned between the electric conductor 22 and the ground shield 23, 25 wherein at least a part of an outer surface of said at least one insulated metallic electrode 27, 28, 29 is not in direct contact with the ground shield 23, 25 and wherein the at least one insulated metallic electrode 27, 28, 29 is spaced from the electric conductor 22.

[0055] The fact that the at least a part of the outer surface of the at least one insulated metallic electrode 27, 28, 29 is not in direct contact with the ground shield 23, 25, means that the at least one insulated metallic electrode 27, 28, 29 is never completely integrated inside the ground shield 23, 25. In this way, the at least one insulated metallic electrode 27, 28, 29 is at least in part in direct contact with a layer set between the electric conductor 22 and the ground shield 23, 25. Said layer at least in part in direct contact with the at least one insulated electrode 27, 28, 29, has an electric potential different from the ground potential of the ground shield 23, 25. Therefore, also the electric potential of the at least one insulated electrode 27, 28, 29 will be different from the ground potential when the cable is energized.

[0056] For example, the at least one insulated metallic electrode 27, 28, 29 can be made of copper or aluminum.

[0057] The at least one insulated metallic electrode 27, 28, 29 can be made in form of a metallic strip 27 describing an arc substantially coaxial with respect to the at least one core 21. In this case the metallic strip 27 faces a respective arc portion of the electric conductor 22 with the interposition of part of the insulation system.

[0058] Alternatively, the insulated metallic electrode 27, 28, 29 can be made in form of a metallic ring 28 substantially coaxial with respect to the at least one core. In this case, the metallic ring 28 completely surrounds the electric conductor 22.

[0059] In a further alternative, the energy harvesting system 10 comprises a plurality of insulated metallic electrodes which are made in form of metallic wires 29 arranged along a circumference substantially coaxial with respect to the at least one core 21.

[0060] In any case, the at least one insulated metallic electrode 27, 28, 29 can comprise an electrode insulating layer 30, 32, 33 that covers at least partially the metallic outer surface of the at least one insulated metallic electrode 27, 28, 29.

[0061] The electrode insulating layer 30, 32, 33 can be made by enamel, or by a tape or by extruded polymer.

[0062] For example, the insulating cover 30 can be made of Polyvinyl Formal, Acetal, Polyvinyl Acetal, polyurethane, polyurethane and external coating polyamide.

[0063] In some embodiments, the at least one insulated metallic electrode 27, 28, 29 is in direct contact with the insulating layer 24.

[0064] In some embodiments, the at least one insulated metallic electrode 27, 28, 29 is in direct contact with the first semiconductive layer 25 of the ground shield 23, 25.

[0065] The at least one insulated metallic electrode 27, 28, 29 can be, then, positioned so as to directly contact the insulating layer 24 and the ground shield 23, 25; more in particular the at least one insulated metallic electrode 27, 28, 29 can be positioned so as to directly contact the insulating layer 24 and the first semiconductive layer 25 as illustrated in FIGS. 1A, 1C and 1D.

[0066] In this case, the at least one insulated metallic electrode 27, 28, 29 must be provided with the electrode insulating layer 30, 32, 33 at least at the interfaces with the first semiconductive layer 25 since the at least one insulated metallic electrode 27, 28, 29 needs to be at a different electric potential with respect to the first semiconductive layer 25.

[0067] Alternatively, the at least one insulated metallic electrode 27, 28, 29 can be completely integrated in the insulating layer 24 as illustrated in FIG. 1B.

[0068] In this case, the at least one insulated metallic electrode 27, 28, 29 can be made also without the electrode insulating layer 30, 32, 33 because the insulation is provided by the insulating layer 24 of the insulation system.

[0069] Preferably, the energy harvesting system 10 comprises electrical connectors connected to the insulated metallic electrode 27, 28, 29 and to the ground shield 23, 25 respectively, wherein said connectors are arranged to be connected to further electrical terminals. In this way the energy harvesting system can be electrically connected to an external device so as to power it with the harvested energy.

[0070] The energy harvesting system 10 can be used in an illuminating system 100 for illuminating the power cable of the energy harvesting system 10. Such an illuminating system 100 comprises the energy harvesting system 10 and at least one system of lighting sources 110 coupled to an outer surface of a respective core 21 or of the power cable and having a first ground terminal 101 directly or indirectly electrically connected to the ground shield 23, 25 and a second terminal 102 directly or indirectly electrically connected to the at least one insulated metallic electrode 27, 28, 29 of the respective core 21.

[0071] The system of lighting sources 110 can comprise a LED strip 111 wound on the outer surface of the respective core 21 or on the outer surface of the power cable 20.

[0072] Alternatively the system of lighting sources 110 can comprise an electroluminescent wire wound on the outer surface of the respective core 21 or on the outer surface of the power cable 20.

[0073] FIGS. 2A, 2B and 2C show three embodiment in which the system of lighting sources 110 comprises a LED strip 111, and the first ground terminal 101 and the second terminal 102 are directly connected to the ground shield 23, 25 and to the at least one insulated metallic electrode 27, 28, 29.

[0074] In particular, in this case the LEDs of the LED strip 111 are configured to be direct and reversely polarized by the potential difference across the two input terminals; in this way the LED strip 111 is powered during the positive cycle as well as in the negative cycle of the sinusoidal harvested voltage. Therefore, the LED strip 111 emits light without interruptions.

[0075] Moreover, in case the at least one core 21 of the energy harvesting system 10 comprises a plurality of insulated metallic electrodes 27, 29 as illustrated in FIG. 2C the insulated metallic electrodes 27, 29 are electrically connected to a single-node 31 which is then electrically connected to the second terminal 102 of the system of lighting sources.

[0076] FIGS. 2D and 2E show two embodiment wherein the illuminating system 100 comprises at least one safety and/or conditioner device 120 having two input terminals 121, 122 electrically connected to the ground shield 23, 25 and to the at least one insulated metallic electrode 27, 28, 29 respectively and two output terminals 123, 124 electrically connected to the first ground terminal 101 and to the second terminal 102 of the system of lighting sources 110 respectively.

[0077] In particular, the at least one safety and/or conditioner device 120 is configured for protecting the system of lighting sources 110 against over-currents and/or over-voltages and/or is configured for rectifying the voltage across the input terminals 121, 122 of the safety and/or conditioner device 120.

[0078] The safety and/or conditioner device 120 can comprise a protection circuit as illustrated in FIG. 2F or a rectifier circuit or a combination of a protection circuit and a rectifier circuit as illustrated in FIGS. 2D and 2E.

[0079] The protection circuit for example comprises a fuse 126 to provide protection against over-currents and a varistor 127 (Voltage Dependent Resistor) to provide protection against over-voltages. For example, the protection circuit can comprise a fuse 126 electrically connected between a second input terminal 122 of the at least one safety and/or conditioner device 120 and a first node 125 that can be directly connected to a second output terminal 124 of the at least one safety and/or conditioner device 120. Moreover, the protection circuit can comprise also a varistor 127 electrically connected between the node first 125 and a second node 128 that is directly connected to a first terminal 121 of the at least one safety and/or conditioner device 120 and that can be directly connected to a first output terminal 123 of the at least one safety and/or conditioner device 120. In FIG. 2F the at least one safety and/or conditioner device 120 comprises only a protection circuit. In this case, the first node 125 is directly connected to the second output terminal 124 and the second node 128 is directly connected to the first output terminal 123. Also in this case the LEDs of the LED strip 111 are configured to be direct and reversely polarized by the potential difference across the two input terminals; in this way the LED strip 111 is powered during the positive cycle as well as in the negative cycle of the sinusoidal harvested voltage. Therefore, the LED strip 111 emits light without interruptions.

[0080] Differently, in FIGS. 2D and 2E the at least one safety and/or conditioner device 120 comprises a rectifier circuit, for example a full wave rectifier or half wave rectifier connected in cascade to the protection circuit. In the particular embodiment illustrated in FIGS. 2D and 2E the rectifier circuit at one side is connected to the first node 125 and to the second node 128 of the protection circuit and at the other side connected to the output terminals 123, 124.

[0081] In case the at least one safety and/or conditioner device 120 comprises a rectifier circuit the LEDs of the LED strip 111 are configured to be direct polarized. The at least one safety and/or conditioner device 120 can be housed in a box and can be mounted at one respective end of the power cable 20.

[0082] In particular, in some embodiments, the power cable 20 is provided at least at one end with a terminal connector 50 adapted to be connected to an end of another power cable or to a power source or to a device; the terminal connector 50 comprises a case 51 inside which electrical contacts 52 are provided. These electrical contacts 52 are adapted to be connected from one side to the at least one core 21 and from the other side to the respective core of the other power cable or to a power source or to a device. In this embodiments the at least one safety and/or conditioner device 120 is housed in a box 53 mounted inside the case 51 of the terminal connector 50. In particular, the box 53 can be is fixed to a wall of the case 51 as depicted in FIG. 3. The box 53 contains all the electronic components of the at least one safety and/or conditioner device 120 leaving accessible the two input terminals 121, 122 and the two output terminals 123, 124.

[0083] The electrical connections between the at least one safety and/or conditioner device 120 and the ground shield 23, 25, the at least one insulated metallic electrode 27, 28, 29, the first ground terminal 101 and to the second terminal 102 of the system of lighting sources 110 are made inside the case 51 of the terminal connector 50, thus resulting safe and reliable not being exposed to the exterior. Moreover, the placement of the at least one safety and/or conditioner device 120 inside the case 51 allows to maintain the continuity of the power cable 20 and an easy access to the at least one safety and/or conditioner device 120.

[0084] In case the illuminating system 100 comprise a plurality of the safety and/or conditioner device 120 they can be mounted along the power cable 20 at predefined lengths.