Power transmission element as well as system and method for insulation monitoring

Abstract

A power transmission element comprising an electrical conductor and insulation of the electrical conductor, which includes an optical fiber unit, characterized in that the optical fiber unit has at least one optical fiber with a reflective end and the electrical conductor has at least along a longitudinal section of the electrical conductor a first winding with the at least one optical fiber and at least along a longitudinal section of the electrical conductor a second winding with an optical fiber crossed with the first winding.

Description

[0001] The present invention relates to a current conduction element comprising an electrical conductor and insulation of the electrical conductor, as well as a system for insulation monitoring, in particular for a current conduction element.

[0002] Defective insulation on electrical conductors poses a hazard in several respects. Stresses on the insulation materials, such as those caused by high electric fields or mechanical stress, can lead to changes in insulation performance or even insulation failure. Exposed conductor sections can cause a short circuit through contact with the conductor. The resulting short-circuit current can lead to damage from overheating in wires and cables, as well as in electrical switchgear. Therefore, insulation monitoring is particularly important for high-power electrical conductors.

[0003] Insulation monitoring is a prerequisite for the safe handling of electrical conductors. This becomes even more important when the conductor is not only intended for handling but also carries high power.

[0004] For example, charging cables for the energy storage units of electric or hybrid vehicles carry high voltages. The charging cable is located either at the charging station or directly on the vehicle and connects the charging station to the vehicle during the charging process. Operation is usually performed by the user of the charging station. It is desirable to ensure that the charging cables have intact insulation to prevent any risk to users when operating the charging cable.

[0005] US 6 559 437 B1, GB 2 164 171 A, US 2011 / 0 209 894 A1 and US 2013 / 0 335 102 A1 each disclose the subject matter of the preamble of claim 1.

[0006] From US 2016 / 0 018 277 A1, which discloses a conductor element with an optical fiber unit for surveillance applications, an optical fiber with a reflective end is known.

[0007] The object of the present invention is to provide a current conduction element that offers increased safety.

[0008] This problem is solved by a current conduction element according to claim 1.

[0009] This invention advantageously provides a current-carrying element that enables the detection of defects in the insulation of the electrical conductor. Defects in the insulation alter the propagation characteristics of light within the optical fiber assembly. In particular, even small defects in the insulation, invisible to the naked eye, lead to changes in light propagation within the optical fiber assembly. This allows even small defects in the insulation to be advantageously detected. A current-carrying element with faulty insulation can thus be easily identified and taken out of service. The current-carrying element according to the invention enables comparatively safe electrical wiring systems.

[0010] In accordance with the present invention, the current conduction element is, for example, designed as an elastic, rigid or flexible current conduction element.

[0011] In accordance with the present invention, the electrical conductor is configured as a single electrical conductor or as a bundle of two or more electrical conductors. The electrical conductor can, for example, comprise a stranded wire or a bundle of stranded wires. The electrical conductor can include supply lines and / or signal lines and / or other lines.

[0012] According to the present invention, the insulation comprises at least one optical fiber unit. The insulation can also comprise two or more optical fiber units.

[0013] In a preferred embodiment of the present invention, the optical waveguide unit surrounds the electrical conductor coaxially at least along a longitudinal section of the electrical conductor.

[0014] The fiber optic cable unit can coaxially surround the electrical conductor along its entire length. This allows for monitoring of the conductor's insulation over its entire length. Alternatively, the fiber optic cable unit can coaxially surround the electrical conductor only along a longitudinal section. This limits the detection of insulation defects to that specific area. This is particularly advantageous in long cable systems with sections subject to varying loads and exposures, as it allows the monitored area to be restricted to the relevant sections of the conductor.

[0015] It is also conceivable that the optical fiber unit coaxially surrounds the electrical conductor in several separate sections, or that different sections of the electrical conductor are coaxially surrounded by different optical fiber units.

[0016] The use of different optical fiber units in different sections of the electrical conductor advantageously facilitates the localization of the insulation defect.

[0017] In a further, preferred embodiment of the present invention, the insulation of the electrical conductor comprises an insulating sheath.

[0018] The insulating sheath preferably surrounds the electrical conductor coaxially. The insulating sheath comprises an insulating material. Any non-conductive material is suitable as an insulating material, for example, from one of the insulating material classes according to DIN EN 60085. Insulating materials include, for example, technical ceramics, plastics (e.g., thermoplastics and / or thermosets), elastomers, electrical insulating paper, polymers, glass, and mica. The insulating sheath can also comprise different insulating materials. In a preferred embodiment, the electrical conductor has a plastic sheath.

[0019] The optical fiber assembly and the insulating sheath can be arranged such that they form coaxially arranged layers around the electrical conductor. In a preferred embodiment, the optical fiber assembly is positioned between the electrical conductor and the insulating sheath.

[0020] In an alternative embodiment, the optical fiber assembly is embedded in the insulating sheath, i.e., the insulating sheath surrounds the optical fiber assembly. This allows for the detection of insulation damage that involves both a breach of the outer layer of the insulating sheath and a breach of the optical fiber assembly. The insulation damage can thus be advantageously detected even if an inner layer of the insulating sheath remains intact.

[0021] According to the invention, the optical waveguide unit has at least one optical waveguide.

[0022] An optical fiber according to the present invention comprises cables and conductors for transmitting light. Preferably, the optical fiber comprises a single optical fiber or an optical fiber bundle. Furthermore, the optical fiber may be partially terminated with connectors.

[0023] Preferably, the optical fiber assembly comprises one optical fiber. In an alternative embodiment, the optical fiber assembly comprises two or more optical fibers.

[0024] According to the invention, the at least one optical waveguide has a reflective end.

[0025] Light coupled into the first end of the optical waveguide is reflected at the second, reflecting end and directed back to the first end. For example, the optical waveguide can have an inscribed interference filter, such as a fiber Bragg grating, at one end. The interference filter reflects light with a wavelength within a predefined filter bandwidth.

[0026] According to the invention, the electrical conductor has at least along a longitudinal section of the electrical conductor a first winding with the at least one optical waveguide.

[0027] The winding provides the insulation with an optical waveguide grid. The density of the winding determines the minimum size of detectable defects. Defects with a smaller diameter cannot be detected by the winding.

[0028] In a preferred embodiment, the winding has a helix. The optical waveguide is wound around the electrical conductor in a helix along its longitudinal axis. The winding is preferably dense, meaning that adjacent sections of the optical waveguide are in contact with each other.

[0029] According to the invention, the electrical conductor has at least along a longitudinal section of the electrical conductor a second winding crossed with the first winding, containing an optical waveguide.

[0030] The electrical conductor has a winding of an optical fiber network, the network comprising a first winding and a second winding that crosses the first. This advantageously creates a dense grid for detecting defects in the insulation of the electrical conductor.

[0031] In a preferred embodiment, the electrical conductor has a winding consisting of a first forward winding in the form of a helix and a reverse winding crossed with the forward winding. The reverse winding can be made with the same optical fiber as the forward winding. The optical fiber preferably has a loop between the forward and reverse windings.

[0032] In an alternative embodiment, the forward winding has a first optical waveguide and the reverse winding has a second optical waveguide, each having a reflective end, so that both evaluation units can be arranged on the same section of the electrical conductor.

[0033] In an alternative, preferred embodiment of the present invention, the optical waveguide unit comprises at least one optically conductive film.

[0034] The optically conductive film is preferably flexible and mechanically robust. The optically conductive film preferably comprises a film, for example a plastic or polymer film, onto which optically conductive structures are applied. Alternatively, the optically conductive structures can be incorporated into the film. The optically conductive film may have a coating.

[0035] In a further, preferred embodiment of the present invention, the at least one optically conductive film has several optical waveguides.

[0036] The optical waveguides are applied to the optically conductive film in a specific geometry. The optical waveguides of the optical film preferably form a dense grid for detecting defects in the insulation of the electrical conductor. Using the optically conductive film, it is possible to easily and quickly equip the electrical conductor with a grid for detecting defects in the insulation.

[0037] In a further preferred embodiment of the present invention, the at least one optically conductive film is connected to at least one optical waveguide.

[0038] Preferably, the optical waveguide focuses the light emerging from the optically conductive film at at least one end. This advantageously makes it possible to return the light emerging from the end of the film to the point of entry. The point of entry is the section of the electrical conductor where the light is coupled into the optical film. However, it is also conceivable to guide the emerging light to any other location, for example, to an evaluation unit.

[0039] It is conceivable that the optically conductive film has a further optical waveguide at an end opposite the at least one end. Preferably, the further optical waveguide guides the light entering the optically conductive film.

[0040] The optical waveguide connected to the optically conductive film can also connect several optically conductive films together. For example, the electrical conductor can have optically conductive films in sections of increased stress to detect any damage to the insulation, with the individual optically conductive films being connected to each other by means of optical waveguides. The optically conductive film furthest from the point of light coupling preferably has an optical waveguide for returning the exiting light.

[0041] In a further preferred embodiment of the present invention, the optical waveguides of the at least one optically conductive film are arranged parallel to each other.

[0042] Preferably, the optical waveguides of the optically conductive film form a grid arranged coaxially to the cylindrical axis of the electrical conductor. The distance between the individual optical waveguides is preferably no larger than the maximum diameter of a breach that can be closed by elastic deformation of the insulation.

[0043] Preferably, the optically conductive film has an optical waveguide that focuses the light emerging from the other optical waveguides of the optically conductive film at one end of the film and returns it to the other end. The ends of the optically conductive film are the side edges of the film that are perpendicular to the parallel optical waveguides.

[0044] In an alternative, preferred embodiment of the present invention, the optical waveguides of the at least one optically conductive film are arranged in a grid, characterized in that light within the at least one optically conductive film is reflectable.

[0045] This makes it advantageously possible to dispense with an optical fiber for returning the exiting light, for example, to the point of entry. The light enters the film, is reflected, and exits at the entry end of the film. Alternatively, it is also possible to couple light from another light source into the film.

[0046] In a further preferred embodiment of the present invention, the at least one optically conductive film comprises at least one evaluation unit and / or at least one measuring unit and / or at least one light source.

[0047] According to the present invention, the evaluation unit is suitable for evaluating at least one property of the light emerging from the optically conductive film before, after, or during its emergence from the film. The evaluation unit can compare this at least one property with a reference value. For example, the evaluation unit can check whether the at least one property exceeds a target value. Alternatively or additionally, the evaluation unit can check whether the at least one property falls below a target value. The evaluation unit can therefore also check whether the at least one property lies within a target interval.

[0048] The light source is suitable for providing light for transport within the optically conductive film.

[0049] A further object of the present invention is a system for insulation monitoring, comprising at least one current-conducting element according to one of claims 1-3, comprising a light source, comprising a coupling unit for coupling the light of the light source into the optical fiber unit of the at least one current-conducting element, further comprising a measuring unit for measuring at least one emission characteristic of the light transported by the optical fiber unit, further comprising an evaluation unit for evaluating the at least one measured emission characteristic of the light transported by the optical fiber unit.

[0050] In a preferred embodiment of the present invention, the light source comprises a diode, for example a superluminescent diode. In a preferred embodiment, the light source can be located downstream of the coupling unit. Alternatively, the light source and the coupling unit can also be configured as a single unit.

[0051] Any property that allows for the detection of changes in light propagation within the optical fiber assembly is suitable as an exit property. Preferably, the exit property is reliably and easily measurable with sufficiently high accuracy. An example of an exit property is the intensity of the light exiting the optical fiber assembly. The exit property is defined as the characteristic that the light exhibits immediately before, during, or immediately after exiting the optical fiber assembly.

[0052] The measuring unit is suitable, for example, for measuring the intensity of the light emerging from the optical fiber unit. The measuring unit preferably includes a photodiode. In a preferred embodiment, the evaluation unit can be connected downstream of the measuring unit. Alternatively, the measuring unit and evaluation unit can also be implemented as a single unit.

[0053] Preferably, the evaluation unit, measuring unit, coupling unit and light source are arranged on the same section of the electrical conductor.

[0054] A further object of the present invention is a method for monitoring the insulation of a power transmission element by means of a system according to claim 4, wherein in a first step light from the light source is coupled into the optical fiber unit, wherein in a second step at least one emission characteristic of the light upon emission from the optical fiber unit is measured by means of the measuring device for measuring the light transported by the optical fiber unit, and wherein in a third step at least one emission characteristic is evaluated by means of the evaluation unit, characterized in that a defect in the insulation of the power transmission element is detected by a deviation of the at least one emission characteristic from a reference value.

[0055] In accordance with the present invention, determining the deviation of the at least one measured outlet property from a reference value includes both checking whether the outlet property exceeds a target value and, alternatively or additionally, checking whether the outlet property falls below a target value.

[0056] Further details, features, and advantages of the invention will become apparent from the drawings and from the following description of preferred embodiments with reference to the drawings. The drawings merely illustrate exemplary embodiments of the invention, which do not limit the essential concept of the invention. Fig. Figure 1 schematically illustrates a system for insulation monitoring. Fig. Figure 2 schematically illustrates a system for insulation monitoring according to a preferred embodiment of the present invention. Fig. Figure 3 schematically illustrates a system for insulation monitoring according to an alternative embodiment not covered by the claims. Fig. Figure 4 schematically illustrates a system for insulation monitoring according to an alternative embodiment, which is also not covered by the claims.

[0057] In the various figures, identical parts are always marked with the same reference symbols and are therefore usually only named or mentioned once.

[0058] In Fig. Figure 1 shows an insulation monitoring system. The insulation monitoring system includes a power line element 2. The power line element 2 is, for example, a charging cable for charging an energy storage unit of an electric or hybrid vehicle. The power line element 2 has a first end 3a and a second end 3b. At the second end 3b, the power line element 2 has a connector 4, for example, a CCS connector. At the first end 3a, the power line element 2 has a coupling unit 5 and a light source 6 connected to the coupling unit 5, for example, in the form of a superluminescent diode. Alternatively, the coupling unit can be arranged at any suitable section of the power line element 2, for example, directly in the charging station, etc.

[0059] The coupling unit 5 is connected to the first end of an optical fiber 7. The light emitted by the light source 6 is coupled into the optical fiber 7 by means of the coupling unit 5. The power transmission element 2 further comprises an electrical conductor 8. For example, the electrical conductor may have supply and signal lines.

[0060] The optical waveguide 7 is wound spirally around the electrical conductor 8, thus providing the electrical conductor 8 with a tightly wound helix. The winding is unidirectional, from the first end 3a to the second end 3b of the electrical conductor element 2. The winding preferably encloses the optical waveguide 7 tightly, i.e., such that adjacent sections 9a, 9b of the optical waveguide 7 are in contact with each other. The winding is coaxially surrounded by an insulating sheath 11.

[0061] The tight winding advantageously provides the electrical conductor 8 with a dense grid for detecting damage to the insulation of the electrical conductor 8. A first end 10a of the optical fiber is connected to the coupling unit 5. This first end 10a is preferably connected to a measuring unit 12. The measuring unit 12 can, for example, be configured as a photodiode. An evaluation unit 13 is connected downstream of the measuring unit 12.

[0062] A second end 10b of the optical fiber terminates in the connector 4 of the power conductor element 2. The second end 10b is reflective. For example, the second end 10b has a fiber Bragg grating.

[0063] The light source 6 emits light, which is coupled into the optical fiber 7 by means of the coupling unit 5. The light propagates along the optical fiber 7, is reflected at its second end 10b, and exits the optical fiber 7 at its first end 10a and enters the measuring unit 12. The measuring unit 12, for example a photodiode, is suitable for measuring at least one property of the light exiting the optical fiber 7. For example, the intensity of the exiting light can be measured. The evaluation unit 13 connected to the measuring unit 12 preferably compares the measured value with a predefined reference interval. Alternatively, the evaluation unit 13 can compare the measured value with a predefined threshold value. If the insulation 14 of the current-conducting element 2, comprising the optical fiber 7 and an insulating sheath 11, is damaged, the propagation of light in the optical fiber 7 is disrupted.For example, cuts or cracks in the optical fiber 7 lead to deviations in the reflection behavior of the light transported in the optical fiber 7. The light is scattered at the damage to the insulation, such as the cut or crack. The intensity of the light exiting at the first end 10a is reduced by such a cut or crack in the insulation 14 of the power conductor 2. The measured value, namely the measured intensity, falls below a threshold value. This is detected by the evaluation unit 13. The evaluation unit 13 is suitable for indicating the detection of a defect in the insulation 14 of the power conductor 2 by means of a signal.

[0064] The coupling unit 5, light source 6, measuring unit 12, and evaluation unit 13 are preferably arranged in a housing. The housing can be located on a suitable section of the power conductor element 2. For example, the housing can be located at a first end 3a of the power conductor element 2. However, it is also conceivable that the housing with the coupling unit 5, light source 6, measuring unit 12, and evaluation unit 13 is attached to the second end 3b of the power conductor element 2 in the connector 4. Accordingly, the first end 10a of the optical fiber 7 is then reflective, and the coupling unit 5 and measuring unit 12 are connected to the second end 10b of the optical fiber 7.

[0065] In Fig. Figure 2 schematically illustrates a system for insulation monitoring 1 according to a preferred embodiment of the present invention. As shown in Fig. In the insulation monitoring system 1, a power line element 2 is included. The power line element 2 is, for example, a charging cable for charging an energy storage unit of an electric or hybrid vehicle. The power line element 2 has a first end 3a and a second end 3b. At the second end 3b, the power line element 2 has a connector 4, for example, a CCS connector. At the first end 3a, the power line element 2 has a coupling unit 5 and a light source 6 connected to the coupling unit 5, for example, in the form of a superluminescent diode. Alternatively, the coupling unit can be arranged at any section of the power line element 2 that appears suitable, for example, located in the charging station, etc.

[0066] The coupling unit 5 is connected to the first end of an optical fiber 7. The light emitted by the light source 6 is coupled into the optical fiber 7 by means of the coupling unit 5. The power transmission element 2 further comprises an electrical conductor 8. For example, the electrical conductor may have supply and signal lines.

[0067] The optical waveguide 7 is wound spirally around the electrical conductor 8. The winding of the optical waveguide 7 comprises a first spiral winding from the first end 3a to the second end 3b and a second spiral winding, crossed with the first, from the second end 3b to the first end 3a. The forward winding 15 and the reverse winding 16 preferably form a tightly wound grid around the electrical conductor 7. At the transition from the forward winding 15 to the reverse winding 16, the optical waveguide 7 has a loop 17. The loop 17 allows the transition from the winding angle of the forward winding 15 to the winding angle of the reverse winding 16. The electrical conductor 8 thus has a tightly wound grid of two crossed helices.

[0068] The rewinding 16 advantageously leads the optical fiber 7 back to the first end 3a of the current-conducting element 2. That is, both ends 10a, 10b are arranged at one end 3a of the current-conducting element 2. This advantageously eliminates the need to design one end 10 of the optical fiber 7 as a reflective end, for example, by inscribing a fiber Bragg grating. The measuring unit 12 is connected to the second end 10b of the optical fiber 7. An evaluation unit 13 is connected downstream of the measuring unit 12.

[0069] The light source 6 emits light, which is coupled into the optical fiber 7 at its first end 10a by means of the coupling unit 5. The light propagates along the optical fiber 7 and exits at its second end 10b, entering the measuring unit 12. In doing so, the light travels the distance between the first end 3a and the second end 3b of the current-conducting element 2 twice. The measuring unit 12, for example a photodiode, is suitable for measuring at least one property of the light exiting the optical fiber 7. For example, the intensity of the exiting light can be measured. The evaluation unit 13 connected to the measuring unit 12 preferably compares the measured value with a predefined reference interval. Alternatively, the evaluation unit 13 can compare the measured value with a predefined threshold value.If the insulation 14 of the power transmission element 2, comprising the optical fiber 7 and an insulating sheath 11, is damaged, the propagation of light in the optical fiber 7 is disrupted. For example, cuts or cracks in the optical fiber 7 lead to deviations in the reflection behavior of the light transported in the optical fiber 7. The light is scattered at the damage to the insulation, such as the cut or crack. The intensity of the light exiting at the second end 10b is reduced by such a cut or crack in the insulation 14 of the power transmission element 2. The measured value, namely the measured intensity, falls below a threshold value. This is detected by the evaluation unit 13. The evaluation unit 13 is capable of indicating the detection of a defect in the insulation 14 of the power transmission element 2 by means of a signal.

[0070] The two ends 10a, 10b of the optical fiber 7 can be arranged close together in the same section of the current conductor element 2. In this case, it is advantageously possible to arrange the coupling unit 5, light source 6, measuring unit 12 and evaluation unit 13 in one housing.

[0071] In Fig. Figure 3 schematically depicts an insulation monitoring system 1 according to an alternative embodiment of the present invention not covered by the claims. The insulation monitoring system 1 comprises a power conductor element 2. The power conductor element 2 is, for example, a charging cable for charging an energy storage unit of an electric or hybrid vehicle. The power conductor element 2 has a first end 3a and a second end 3b. At the second end 3b, the power conductor element 2 has a connector 4, for example, a CCS connector. At the first end 3a, the power conductor element 2 has a coupling unit 5 and a light source 6 connected to the coupling unit 5, for example, in the form of a superluminescent diode. Alternatively, the coupling unit can be arranged at any section of the power conductor element 2 that appears suitable, for example, in the charging station, etc.

[0072] The coupling unit 5 is connected to a first end 20a of an optically conductive film 18. Preferably, the optically conductive film is flexible and has a plurality of optical waveguides 19.

[0073] The light emitted by the light source 6 is coupled into the optically conductive film 18 at the first end 20a by means of the coupling unit 5. The current-conducting element 2 further comprises an electrical conductor 8. For example, the electrical conductor has supply and signal lines.

[0074] The optically conductive film 18 is arranged coaxially around the electrical conductor 8. The optically conductive film 18 forms a cylinder directly on and surrounding the electrical conductor. The optically conductive film 18 preferably comprises optical waveguides 19. In an embodiment not covered by the claims, the optical waveguides 19 are arranged parallel to each other on the film 18. Preferably, the distance between the optical waveguides 19 is 0.5 mm or less. This allows cracks and damage in the insulation 14 that are larger than 0.5 mm to be detected. Damage and cracks that are smaller than 0.5 mm can be closed by elastic deformation of the insulating material.

[0075] At a second end 20b, the optically conductive film 18 has an optical waveguide 21. The optical waveguide 21 focuses the light emerging from the optically conductive film 18. In an embodiment not covered by the claims, the second end 20b of the optically conductive film 18 is located at the second end 3b of the current-conducting element 2. The optical waveguide 21 extends from the second end 3b to the first end 3a of the current-conducting element 2. The measuring unit 12 is connected to the optical waveguide 21. An evaluation unit 13 is connected downstream of the measuring unit 12.

[0076] The light source 6 emits light, which is coupled into the optically conductive film at the first end 20a by means of the coupling unit 5. The light propagates along the optical waveguides 19 in the optically conductive film 18 and exits the film at the second end 20b. At the second end 20b, the light is focused in an optical waveguide 21 and guided back to the first end 3a. Here, the light exits the optical waveguide 21 and enters the measuring unit 12. In doing so, the light travels the distance between the first end 3a and the second end 3b of the current-conducting element 2 twice. The measuring unit 12, for example a photodiode, is suitable for measuring at least one property of the light exiting the optical waveguide 7. For example, the intensity of the exiting light can be measured. The evaluation unit 13 connected to the measuring unit 12 preferably compares the measured value with a predefined reference interval.Alternatively, the evaluation unit 13 can compare the measured value with a predefined threshold value. If the insulation 14 of the current-conducting element 2, comprising the optically conductive film 18 and an insulating sheath 11, is damaged, the propagation of light in the optical waveguide 7 is disrupted. For example, cuts or cracks in the optically conductive film 18 lead to deviations in the reflection behavior of the light transported in the optically conductive film 18. The light is scattered at the damage to the insulation, such as the cut or crack. The intensity of the light exiting at the second end 10b is reduced by such a cut or crack in the insulation 14 of the current-conducting element 2. The measured value, namely the measured intensity, falls below a threshold value. This is detected by the evaluation unit 13.The evaluation unit 13 is suitable to indicate the detection of a defect in the insulation 14 of the current conductor element 2 by means of a signal.

[0077] In an alternative embodiment, also not covered by the claims, the optical waveguides 19 can be arranged in a grid on the optically conductive film 18, see Fig.4. The light is then reflected within the optically conductive film 18. Focusing and redirecting the light from the second end 20b of the optically conductive film 18 to the first end of the optically conductive film 18 is therefore unnecessary. The light is coupled into the film 18 at the first end 20a and also exits the film 18 at the first end 20a. In this embodiment, the measuring unit 12 is connected to the second end 20b of the optically conductive film 18. The evaluation unit 13 is, for example, connected downstream of the measuring unit 12. The density and size of the grid meshes determine the size of the minimum detectable defects in the insulation 14. The coupling unit 5, light source 6, measuring unit 12, and evaluation unit 13 can be arranged in a single housing.In an alternative embodiment, also not covered by the claims, the coupling unit 5, the light source 6, the measuring unit 12, and the evaluation unit 13 are integrated into the optical film 18. This advantageously makes it possible to output only the evaluated signal from the optical film 18. In a further alternative embodiment, also not covered by the claims, only at least one of the components—coupling unit 5, light source 6, measuring unit 12, and evaluation unit 13—is integrated into the optical film 18, while the remaining components remain outside the optical film.

Claims

[1] Power transmission element comprising an electrical conductor and insulation of the electrical conductor, which includes an optical waveguide unit, characterized by , that the optical fiber assembly has at least one optical fiber with a reflective end and the electrical conductor has at least along a longitudinal section of the electrical conductor a first winding with the at least one optical fiber and at least along a longitudinal section of the electrical conductor a second winding with an optical fiber crossed with the first winding. [2] Power transmission element according to claim 1, wherein the optical waveguide unit coaxially surrounds the electrical conductor at least along a longitudinal section of the electrical conductor. [3] Current conduction element according to one of the preceding claims, wherein the insulation of the electrical conductor comprises an insulating sheath. [4] System for insulation monitoring, comprising at least one current conductor element according to one of the preceding claims, comprising a light source, comprising a coupling unit for coupling the light of the light source into the optical fiber unit of the at least one current conductor element, further comprising a measuring unit for measuring at least one emission characteristic of the light transported by the optical fiber unit, further comprising an evaluation unit for evaluating the at least one measured emission characteristic of the light transported by the optical fiber unit. [5] Method for insulation monitoring of a power line element using a system according to claim 4, in a first step, light from the light source is coupled into the optical fiber unit, wherein in a second step at least one exit property of the light is measured upon exit from the optical fiber unit by means of the measuring device for measuring the light transported through the optical fiber unit and wherein in a third step at least one exit property is evaluated using the evaluation unit, characterized by , that a defect in the insulation of the current conductor element is detected by a deviation of at least one output characteristic from a reference value.

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