Assembly and cell for studying the aging of high-voltage cables

Abstract

Assembly and cell for studying the aging of high-voltage cables. The invention relates to a method for manufacturing an assembly (2) for studying the aging of a high-voltage cable (1). The method comprises forming a multilayer stack consisting of a first electrode layer (202), at least one first insulating polymer layer (201), a second electrode layer (203), such that the first insulating polymer layer (201) is positioned between the first (202) and second (203) electrode layers, and a separating layer (204) between the first (202) and second (203) layers. The multilayer stack (20) is wound at least partially around itself in a longitudinal direction (A2) to form the assembly (2). Figure for the abstract: Fig. 7

Description

Title of the invention: Assembly and cell for studying the aging of high-voltage cables technical field

[0001] The present invention relates to the field of studying the aging of electrical cables, and in particular high-voltage electrical cables. Its particularly advantageous application lies in predicting the mechanical and electrical behavior of high-voltage cable components, with the aim of improving their manufacture and / or predicting their lifespan. STATE OF THE ART

[0002] Generally, and for example as illustrated in [Fig. 1], a high-voltage cable comprises, in its cross-section, a core 11 surrounded by an inner semiconducting sheath 12, itself surrounded by an insulating material 13 based on an electrically insulating polymer. The core 11 generally comprises metallic wires 110, for example braided together. The insulating material 13 is typically surrounded by an outer semiconducting sheath 14, surrounded by an electromagnetic shield 15 and then by an outer electrically insulating sheath 16.

[0003] High-voltage cable breakage is often due to the insulating material surrounding the inner semiconducting sheath, or to the material of the outer semiconducting sheath. Therefore, there is a need to study the aging of these materials of interest in order to improve the reliability of high-voltage cables and / or predict their lifespan.

[0004] The modelling, prediction and expertise of the aging of dielectrics and semiconductors composing high voltage cables is typically done by an accelerated aging approach under coupled conditions between exposure to an electric current, and mechanical and / or thermal stresses in an environment representative of the use of the high voltage cable, for example without oxygen with the presence of humidity.

[0005] For high-voltage electrical cables, the approach used by cable manufacturers is to develop miniature prototype cables with a cross-section and length smaller than those of standard high-voltage cables. These miniature cables are then aged in temperature-controlled chambers. These chambers are generally connected to an external high-voltage generator to supply the cables with electricity. This technique allows for the coupling of two acceleration factors: temperature and electric field.

[0006] However, the mini-cable approach offers a small volume of material for studying changes in material properties. Materials studies require a large number of samples to properly establish statistics mechanical and dielectric embrittlement. Furthermore, the microstructure, thermomechanical history, and mechanical state of a mini-cable differ from those of a true high-voltage cable. These differences pose a problem for representativeness in aging studies and cable lifetime prediction.

[0007] Another solution used consists of shaping the insulating material in its molten state to produce specific specimens, known as Rogowski-type specimens, on which the aging study is conducted. This generally involves using granules of the same polymer as that used in a high-voltage cable, which is shaped by compression to manufacture the specimen. In the case of Rogowski-type specimens, the degree of representativeness is therefore even lower. Reshaping the material leads to a significant departure from the material's actual behavior and its thermo-mechanical history during the manufacture of the high-voltage cable. Furthermore, the preparation of each specimen is tedious, which limits the statistical value of the aging study.

[0008] An object of the present invention is therefore to propose a solution improving the study of the aging of high voltage electrical cables.

[0009] The other objects, features and advantages of the present invention will become apparent from an examination of the following description and accompanying drawings. It is understood that other advantages may be incorporated. SUMMARY

[0010] To achieve this objective, according to a first aspect, a manufacturing process for an assembly for studying the aging of an electrical cable, and in particular a high-voltage cable, is provided, the process comprising: - the formation of a multilayer stack comprising at least partial superposition: • a first layer called the electrode, made of an electrically conductive material, • at least one layer based on an electrically insulating polymer, called the first insulating polymer layer, • a second layer, called the electrode layer, made of an electrically conductive material, such that the first insulating polymer layer is positioned between the first and second electrode layers, and • a separating layer at least partially overlapping with the assembly formed by the first and second electrode layers and the first insulating polymer layer, - a winding of the multilayer stack at least partially around itself around a longitudinal direction to form the assembly.

[0011] The electrical aging of a cable is a function of the electromotive force in the cable. This force depends on the voltage and the thickness of the material through which the electric current flows. The use of an insulating polymer layer in a stack, this layer being particularly thin compared to existing solutions, makes it possible to reduce the voltage required to obtain exposure to an electric current more representative of the actual wear of a high-voltage cable. The aging study is thus facilitated and is also more representative of real-world aging.

[0012] Furthermore, since the insulating polymer is in the form of a layer sandwiched between the electrodes, the assembly allows for better exposure of the insulating polymer layer to electrical and thermal stresses compared to existing solutions. The aging study is thus made more reliable.

[0013] This multilayer stacking configuration allows accelerated aging of this layer while obtaining a sufficient volume of material to carry out the aging study, and in particular mechanical and dielectric analyses.

[0014] In addition, the assembly is simplified compared to existing solutions, which facilitates the creation of several assemblies to improve the statistics of an aging study.

[0015] The aging study is therefore improved, in particular compared to existing solutions using mini-cables.

[0016] A second aspect concerns an assembly for studying the aging of an electrical cable, and in particular a high-voltage cable. The assembly comprises a multilayer stack at least partially wound around itself in a longitudinal direction, the multilayer stack comprising: - a first and second layer, called electrode layers, made of an electrically conductive material, - a first layer based on an electrically insulating polymer of high-voltage cable, called the first insulating polymer layer, and disposed between the first and second electrodes, and - a separator layer configured to electrically isolate the first and second electrode layers from each other, in the wound multilayer stack.

[0017] The assembly thus presents the effects and advantages described above with reference to the manufacturing process according to the first aspect.

[0018] A third aspect relates to a cell for studying the aging of a high-voltage cable, comprising: - assembly according to the second aspect or manufactured according to the first aspect, and - a capsule configured to electrically power the assembly, the capsule comprising: • a body, a first stopper and a second stopper, defining a closed internal volume, the capsule being configured to receive the assembly within the closed internal volume, • two electrodes each configured to connect a separate electrode layer of the assembly.

[0019] The cell thus makes it possible to carry out the aging study of the assembly by electrical connection to an external power supply.

[0020] A fourth aspect relates to a system comprising several cells according to the third aspect and a box configured to receive and electrically supply the cells.

[0021] The system thus makes it possible to parallelize aging studies for several cells. This allows, in particular, for obtaining aging statistics for samples of the same type of electrical cable. In synergy with sealed capsules, this allows for parallel aging studies to be carried out under different aging conditions. The system is therefore particularly advantageous given the duration of aging studies, which can, for example, last several years.

[0022] A fifth aspect relates to a method for studying the aging of an electrical cable, and in particular a high-voltage cable, the method comprising: - an exposure of at least one assembly according to the second aspect or manufactured according to the process according to the first aspect, to an electric current, - at least one measurement of an electrical property, and for example of the internal resistance, of at least one assembly so as to obtain a data representative of the aging of a high voltage cable.

[0023] The assembly can be contained within a cell according to the third aspect. The assembly can be contained within a cell according to the fourth aspect. BRIEF DESCRIPTION OF THE FIGURES

[0024] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings.

[0025] [Fig.1] Fig.1 represents a cross-sectional view of a high-voltage cable, according to an example of an embodiment.

[0026] [Fig.2] Fig.2 represents a side view of a portion of high-voltage cable, based on an example of implementation.

[0027] [Fig.3] Fig.3 represents a view of one end of a cut portion of high-voltage cable, according to an example embodiment.

[0028] [Fig.4] Fig.4 represents a perspective view of the straightening steps of the cut portion of high-voltage cable, according to an example of embodiment.

[0029] [Fig.5] The [Fig.5] represents a perspective view of the trimming of the portion of high-voltage cable, according to an example of embodiment.

[0030] [Fig. 0A] Figures 6A to 6C respectively represent side, top and other side views of the multilayer stack before winding, according to an example of an embodiment.

[0031] [Fig. B]

[0032] [Fig. 0C]

[0033] [Fig.7] Fig.7 represents a cross-sectional view of the assembly, according to an example embodiment.

[0034] [Fig.8] Fig.8 represents a cross-sectional view of the cell comprising the assembly illustrated in [Fig.7], according to an example embodiment.

[0035] [Fig.9] Fig.9 represents a cross-sectional view of the system, according to an example of an embodiment.

[0036] [Fig. 10] The [Fig. 10] represents a cross-sectional view of the system illustrated in [Fig.9], in a temperature-controlled enclosure, according to an example of an embodiment.

[0037] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. In particular, the relative dimensions of the layers and layer thicknesses in the stack are not representative of reality. DETAILED DESCRIPTION

[0038] Before beginning a detailed review of embodiments of the invention, optional features which may possibly be used in association or alternatively are stated below.

[0039] According to one example, the process further comprises: - the supply of a portion of high-voltage cable comprising a core extending along a principal direction of cable extension and surrounded around said direction by a material based on the electrically insulating polymer, - the formation of a film based on the electrically insulating polymer, by contouring the portion of high-voltage cable around the main extension direction of the cable, at least a portion of the film being used during the formation of the multilayer stack.

[0040] Thus, the assembly for the aging study is made from a real high-voltage cable. The material studied exhibits a maximum degree of representativeness because its microstructural structure, any additives, thermomechanical history, and mechanical state at the end of manufacturing are those of a real cable, for example, one taken from its transport reel. By trimming, the resulting film is also representative of the aging of the material of interest at a given point in the cross-section of the high-voltage cable. It is therefore possible to study the aging over all or part of the cross-section of the cable material(s) constituting the film.

[0041] Furthermore, this method allows the cable segment to be exposed to aging, or a cable segment already aged through use to be studied. This makes it possible to conduct aging studies under conditions that more closely approximate the actual wear of a cable, and, for example, to analyze the possible causes in the event of a high-voltage cable break. According to one example, the method comprises, prior to film formation, aging of the high-voltage cable, including exposure of the cable segment to an electric current, and / or in which the cable segment is taken from a previously used high-voltage cable.

[0042] According to one example, the winding of the multilayer stack is carried out under an atmosphere with controlled humidity and / or oxygen levels. Thus, the environmental aging conditions of the cable can be reproduced at the assembly level at the level of the insulating polymer layer.

[0043] According to one example, the method includes the arrangement of the assembly in the capsule described in the third aspect of the invention.

[0044] According to one example, the arrangement of the assembly in the capsule described in the third aspect of the invention is carried out under a controlled humidity atmosphere. The arrangement of the assembly in the capsule can be followed by the airtight sealing of the capsule.

[0045] According to one example, the method further comprises, prior to the formation of the multilayer stack, a selection of the portion of the film to form the multilayer stack, according to the corresponding position of the electrically insulating polymer-based material in the high-voltage cable. It is thus possible to analyze the aging according to the location of the material in the cable, and, for example, to carry out these analyses for distinct locations radially and / or longitudinally in the cable.

[0046] According to one example, the process comprises, before the film is formed: - straightening a lateral perimeter of the portion of cable, and / or - training of at least one, and preferably each, end of the cable section.

[0047] Due to the mechanical stresses exerted within a high-voltage cable, and particularly following cutting to obtain the cable section, these straightening processes allow each section to have a better quality working surface for trimming. Thus, defects induced by the cutting and not related to manufacturing or normal cable aging can be eliminated from the resulting assembly.

[0048] According to one example, the insulating polymer layer is obtained from the trimming of a high-voltage cable.

[0049] The assembly can be obtained by the process according to the first aspect.

[0050] According to one example, at least one of the first and second electrode layers protrudes at least partially beyond the first insulating polymer layer and the separating layer in the longitudinal direction. Electrical connection of the electrode is thus facilitated on the portion of the electrode protruding beyond the other layers.

[0051] Preferably, each of the first and second electrode layers protrudes from the first insulating polymer layer and the separator layer in the longitudinal direction, such that the first electrode layer protrudes from the first insulating polymer layer and the separator layer on one side of the stack with respect to the longitudinal direction, preferably without protruding on a second side opposite to the first side, and the second electrode layer protrudes from the first insulating polymer layer and the separator layer on the second side of the stack, preferably without protruding on the first side,

[0052] According to one example, the first and second electrode layers are arranged in a staggered manner relative to the first insulating polymer layer and the separating layer in the longitudinal direction, such that: - the first electrode layer protrudes beyond the first insulating polymer layer and the separator layer on one side of the multilayer stack relative to the longitudinal direction, without protruding on a second side of the multilayer stack opposite the first side, - the second electrode layer protrudes from the first insulating polymer layer and the separator layer on the second side of the multilayer stack, without protruding on the first side.

[0053] The electrical connection of each electrode is thus simplified while maintaining a simple assembly configuration. Furthermore, the offset of the electrode layers allows these layers to extend beyond the others over a significant portion of their length, and preferably along their entire length. The electrical connection will therefore be further simplified. Thus, each electrode is exposed on one face of the winding, and more specifically on its ends on either side of the longitudinal direction, which faces will serve as the accessible electrical connections.

[0054] According to one example, the first insulating polymer layer has a thickness of substantially between 50 µm and 200 µm, preferably between 70 µm and 150 µm, and preferably approximately 100 µm. The thickness of the insulating polymer layer in these ranges is particularly suitable for reducing the applied voltage while maintaining a representative electromotive force. This thickness is particularly advantageous for achieving uniform aging throughout its thickness. A thinner thickness exacerbates the material's fragility after aging. Excessive thickness induces heterogeneous aging, typically with an oxidized layer on either side of the insulating polymer layer. At 100 µm, any potential porosity is prevented from creating holes and weakening the insulating film.

[0055] According to one example, the separating layer is a layer based on an electrically insulating material, and preferably an electrically insulating polymer.

[0056] According to one example, the separating layer is a second layer based on the electrically insulating polymer of high-voltage cable, referred to as the second insulating polymer layer. Preferably, each insulating polymer layer has a thickness substantially between 50 µm and 200 µm, preferably a thickness substantially between 70 µm and 150 µm, preferably substantially equal to 100 µm.

[0057] In one example, the separating layer is an adhesive. In another example, the separating layer is a film resulting from a different cutting process.

[0058] According to one example, the separating layer is a layer based on a polymer chosen from the group consisting of polyimide (PI), polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), cross-linked polyethylene (PEr), ultra-high-molecular-weight polyethylene (UHMWPE), ethylene-propylene-diene monomer rubber (EDPM), polyamide (PA), polyoxymethylene (POM), polyetheretherketone (PEEK), polyethylene terephthalate (PET).

[0059] According to one example, the separating layer is a layer based on a polymer chosen from the group consisting of polyimides (PI). The assembly is thus particularly suitable for aging studies at very high voltage, for example for voltages approximately equal to 10,000 V.

[0060] According to one example, the separating layer can be obtained by trimming a portion of cable distinct from the portion of cable from which the insulating polymer layer is derived. It is thus possible to age two samples from different cable sections under identical conditions.

[0061] According to one example, the assembly includes an internal support around which the multilayer stack is wound. Preferably, the internal support is electrically insulating.

[0062] According to one example, the cell body and the first and second stoppers are configured to define the sealed internal volume. The sealed capsule thus maintains an internal atmosphere, so as to adapt to the aging conditions as needed, for example according to the humidity level and / or the presence or absence of oxygen.

[0063] According to one example, in the assembly, at least one of the first and second electrode layers protrudes at least partially beyond the first insulating polymer layer and the separating layer in the longitudinal direction, so as to be in electrical contact with the corresponding electrode of the capsule, which is positioned opposite said electrode layer. The capsule thus allows for a simplified electrical connection with the assembly, in synergy with the protrusion of the electrode(s) of the assembly.

[0064] Preferably, each of the first and second electrode layers protrudes from the first insulating polymer layer and the separator layer in the longitudinal direction, so that the first electrode layer protrudes from the first insulating polymer layer and the separator layer on one side of the stack with respect to the longitudinal direction, preferably without protruding on a second side opposite to the first side, and the second electrode layer protrudes from the first insulating polymer layer and the separator layer on the second side of the stack, preferably without protruding on the first side, so as to be in electrical contact with the corresponding electrode, arranged opposite said electrode layer.

[0065] According to one example, at least one, and preferably each, electrode of the capsule is compressed against the corresponding electrode layer of the assembly, and against the corresponding plug. The electrical connection is made more reliable. The aging study will therefore be more reliable.

[0066] According to one example, each cap is electrically conductive and is electrically connected to an electrode of the capsule, the body of which is configured to electrically insulate the first and second caps from each other. This facilitates the electrical connection of the capsule to an external power source. In synergy with the protrusion characteristics of the electrode layers and / or the compression of the capsule electrode(s), it is understood that the successive electrical connections are made more reliable.

[0067] According to one example, the body of the capsule comprises: - a first electrically insulating sleeve surrounding the assembly laterally, - a second metal sleeve laterally surrounding the first sleeve, the second sleeve preferably being in electrical contact with the second plug, and - an electrically insulating collar separating the first cap from the second sleeve.

[0068] The assembly is thus electrically isolated from the capsule body. The second metal sleeve improves the thermal conductivity of the capsule. This therefore improves the transmission of thermal energy to the assembly during an aging study.

[0069] According to one example, the capsule is configured to form a leak-proof and removable seal at the collar. For example, a first sealing gasket can be positioned at the point where the first cap abuts against the collar.

[0070] For example, a second sealing gasket can be disposed at the level of a butting area of ​​the second sleeve on the collar.

[0071] According to one example, the system comprises a number of cells greater than or equal to 50, preferably greater than or equal to 100.

[0072] According to one example, the housing comprises: - a first cover comprising several electrical connectors, the electrical connectors being configured to each electrically connect at least one cell, separately from the at least one cell connected by the other electrical connectors, and - a second cover configured to electrically connect the electrical connectors of the first cover together to an external power source.

[0073] The first cover allows for the differentiated analysis of the electrical properties of each cell, and therefore of each assembly. Since variability between cells can be observed, a measurement can be taken for each assembly. Furthermore, it is possible to perform in situ measurements without dismantling the entire system. This is particularly advantageous given the duration of the aging studies, and therefore the number of measurements required.

[0074] The second cover allows for parallel power supply for aging the assemblies and simplifies the connection of the cells to the external power source. The system is thus modular between diagnostic and aging phases, which simplifies the aging study.

[0075] According to one example, the cell and / or the system include the external power supply.

[0076] As an example, the electric current has a voltage between 5,000 V and 20,000 V in the aging study process. These voltages allow the assembly to age in order to evaluate the aging of a corresponding high-voltage cable. In synergy with the thickness of the insulating polymer layer, these voltages allow for homogeneous aging that is representative of the electromotive force in a high-voltage cable under use.

[0077] In the following description, the term "on" does not necessarily mean "directly on." Thus, when it is stated that a part or component A is supported "on" a part or component B, this does not mean that parts or components A and B are necessarily in direct contact with each other. These parts or components A and B may be either in direct contact or supported by each other via one or more other parts. The same applies to other expressions such as, for example, the expression "A acts on B," which may mean "A acts directly on B" or "A acts on B via one or more other parts."

[0078] In this patent application, when two parts are described as distinct, this means that these parts are separate. They may be: - positioned at a distance from each other, and / or - mobile relative to each other and / or - joined together by being fixed by added elements, this fixing being removable or not.

[0079] A single-piece unit cannot therefore be made up of two separate parts.

[0080] In this patent application, the term "fixed" used to describe the connection between two parts means that the two parts are linked / fixed to each other with respect to all degrees of freedom, unless explicitly specified otherwise. For example, if it is stated that two parts are fixed in translation along a direction X, this means that the parts can be movable relative to each other, possibly with respect to several degrees of freedom, excluding freedom in translation along the direction X. In other words, if one part is moved along the direction X, the other part moves in the same direction.

[0081] For the purposes of this disclosure, the expression "A and / or B" means (A), (B), or (A and B). For the purposes of this disclosure, the expression "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0082] A layer, or a material based on a species A, is understood to mean a layer, or a material comprising only that species A or that species A and possibly other species, for example additives.

[0083] A parameter "approximately equal to / greater than / less than" a given value means that this parameter is equal to / greater than / less than the given value, to within ±10% of that value. A parameter "approximately between" two given values ​​means that this parameter is at least equal to the smaller of the given values, to within ±10% of that value, and at most equal to the larger of the given values, to within ±10% of that value.

[0084] The various aspects of the invention are now described according to embodiment examples with reference to the figures.

[0085] As illustrated in Figures 2 to 7, an assembly 2 is used to study the aging of a high-voltage electrical cable 1. A high-voltage electrical cable, or equivalently a high-voltage cable, is defined as an electrical cable configured to carry a voltage greater than or equal to 200,000 V, typically between 200,000 V and 500,000 V, for example, 225,000 V and / or 275,000 V. A high-voltage cable typically has a cross-sectional area greater than or equal to 80 mm². In the following, the term "cable" is used to refer to a high-voltage cable.

[0086] The assembly 2 is manufactured by forming a multilayer stack 20 comprising at least a partial overlap of layers. This overlap comprises, with reference to Figures 6A to 7: - a first electrode layer 202, based on or made of an electrically conductive material, - a layer of insulating polymer 201 for high-voltage cable, - a second layer, called electrode 203, based on or made of a material electrically conductive, and - of a separating layer 204.

[0087] This stack 20 is wound around itself about a winding direction A2, to form a coil of the multilayer stack having a longitudinal direction A2. The term longitudinal is used more specifically to designate the principal extension direction of the assembly, once wound. The direction A2 is here more specifically parallel to the z-direction. Preferably, the multilayer stack 20 is entirely wound around itself along the length direction of the stack's layers. By way of example, the multilayer stack 20 wound around itself comprises only the aforementioned layers, that is, without any additional layers included in the stack.

[0088] The insulating polymer layer, also referred to as the first insulating polymer layer 201, is arranged between the first 202 and second 203 electrode layers. Thus, the insulating polymer layer 201 can be exposed to an alternating electric current or continuous, so as to simulate accelerated aging of this material, in the context of an aging study of a high voltage cable 1.

[0089] The separator layer 204 is configured to electrically insulate the first 202 and second 203 electrode layers from each other. The separator layer 204 is therefore at least partially superimposed on the assembly formed by the first 202 and second 203 electrode layers and the first insulating polymer layer 201. More specifically, the separator layer 204 can be positioned below or above the assembly formed by the first 202 and second 203 electrode layers and the first insulating polymer layer 201. Once the multilayer stack 20 is wound, the separator layer 204 is positioned between the first 202 and second 203 electrode layers so as to electrically insulate them.

[0090] To manufacture this assembly 2, as illustrated in [Fig. 2], a portion 10 of cable 1 can be provided. Thus, the assembly 2 is made from an actual high-voltage cable. As illustrated in [Fig. 1], this portion 10 may comprise, in its cross-section, a core 11 surrounded by an inner semiconducting sheath 12, itself surrounded by an insulating material 13 based on an electrically insulating polymer. The core 11 may comprise metallic wires 110, for example, braided together. The insulating material 13 may be surrounded by an outer semiconducting sheath 14, surrounded by an electromagnetic shield 15 and then by an electrically insulating outer sheath 16.

[0091] Portion 10 can be cut from a cable 1, for example by cutting. This cutting operation can generate numerous defects at the ends 10a and 10b. These defects can be explained by internal stresses in the cable 1. These internal stresses can, in particular, cause shrinkage of the dielectric material 13 along the principal extension direction Al of portion 10 of cable 1. In addition, defects related to the cutting operation, such as metallic particles or sheath debris, may be observed.

[0092] In order to eliminate these defects, and as illustrated in [Fig. 4] for example, the method may include straightening the cable portion 10. Straightening of the lateral circumference 100 of the cable portion 10 can be carried out, for example along arrow FL. This straightening can be configured so as to remove the elements of the cable 1 down to the electromagnetic shielding 15, and in particular the outer insulating sheath 16. Thus, the circumference of the cable 1 is restored to a cylindrical shape. Straightening can be carried out at at least one and preferably at each end 10a, 10b of the cable portion 10, for example along arrows F2 and F3. This straightening is preferably done so as to flatten the cross-section at the end 10a, 10b, preferably to correct the shrinkage of the insulating material. This makes it possible to correct defects related to cutting and related to internal stresses in cable 1. These straightenings can be carried out on a conventional lathe.

[0093] These cutting and / or straightening steps can generate a significant amount of debris and dust, which can affect the behavior of assembly 2 during the aging study, and for example, induce breakdown of the insulating polymer in the first layer 201. The data collected during the aging study may therefore be affected. The process may include one or more cleaning steps to prevent metallic and plastic contamination. This cleaning may be performed using compressed air, mechanical methods (e.g., brushing, ultrasonics), a liquid medium, or a combination of these conditions (e.g., an ultrasonic bath).

[0094] A film 200 can then be formed by cutting the portion 10 of cable 1 around the main extension direction Al of the portion 10 of cable 1. As illustrated, for example, by [Fig. 5], a blade 6 can cut a film 200 by relative rotation between the blade 6 and the portion 10 of cable 1 around the axis Al, and in particular by rotation of the portion 10 of cable 1. This operation can be performed by a conventional turning device. The cutting operation can be carried out from the electromagnetic shield 15 to the inner semiconducting sheath 12. According to our example, the electromagnetic shield 15 can be removed before the cutting operation, the cutting then being carried out from the outer semiconducting sheath 14. The shield can be removed by a turning operation on the outer periphery of the portion 10 of cable.This operation also allows the cylindricity of section 10 to be corrected, which is often bent by the winding of the cable onto the reel. Depending on the position of the cable section on the reel, the bend is more or less pronounced.

[0095] It is also possible to cut out the inner semiconducting sheath 12. To do this, the metal core 11 can be completely machined to remove all the metallic elements from the cable portion 10, cleaning to eliminate all metallic contamination. The hole left by the core 11 could then be plugged with an insulating polymer core (polyethylene, for example), for instance, press-fitted to allow the cutout to be made right down to the semiconductor of the inner sheath and even beyond, into the insulating polymer core, to fully recover the internal semiconductor.

[0096] The trimming operation can, for example, produce a film length 200 greater than or equal to 10 m, preferably greater than or equal to 20 m, and even more preferably substantially equal to 30 m. The film 200 can comprise a portion based on or made of the electrically insulating polymer, and a portion based on or made of the outer sheath semiconductor 14. The portion based on or made of the outer sheath semiconductor 14 can have a length greater than or equal to 1 m, for example substantially equal to 1.5 m.

[0097] Only a portion 200a of the film 200 can be used to form the multilayer stack 20. The process can therefore include cutting this portion 200a from the film 200. This portion 200a can be selected in the film 200 according to its corresponding location in the cable 1, for example locations 200b or 200c illustrated in [Fig.5].

[0098] Note that the film 200 obtained by trimming exhibits scratches (traces of the cutting edge) on the wire, resulting from vibration during cutting. Under polarized light, local deformations related to the cutting can be observed by birefringence. On an extruded film, the surface is smooth and free of local deformations.

[0099] From a film 200, it is therefore understood that several assemblies 2 can be manufactured. The process thus makes it possible to manufacture, in a simplified way compared to existing solutions, several assemblies 2. It is therefore possible to have more data for the study of aging and therefore more statistics available. As seen above, this data can, for example, take into account the radial location of the insulating material 13 in the cable 1. It is also possible to specify that the portion 10 of cable 1 is chosen according to the location of the portion 10 in the cable 1.Even more statistical data can be obtained from the study.

[0100] Prior to the formation of the film 200, the process may include aging a portion 10 of cable 1, for example by exposing it to given electrical, mechanical, and / or thermal conditions, described in a later example. Because only a portion 10 of cable 1 is used, and not an entire high-voltage cable, it is indeed possible to subject this portion to aging in order to study its impact on the material structure as closely as possible to real-world conditions. Alternatively, a portion 10 from a cable 1 already used for high-voltage power supply, which has already aged naturally under real-world operating conditions, for example in a particularly stressed area of ​​the power grid, may be used.

[0101] The portion 200a will thus form the first layer of insulating polymer 201 of the multilayer stack 20. The multilayer stack 20 is now described in more detail with reference to [Fig. 0A] to 6C.

[0102] Each layer of the stack 20 has a length and a width, the length along the y direction being greater than the width along the z direction. The longitudinal winding direction A2 can be substantially perpendicular to the length direction of each layer.

[0103] The different layers of the stack 20 can be arranged with each other in such a way as to facilitate the electrical connection of the electrode layers 202, 203.

[0104] To this end, and as illustrated by Figures 6A to 6C, the layers of the multilayer stack 20 can be offset from each other. More specifically, each layer The electrode 202, 203 may protrude from the first insulating polymer layer 201 and the separating layer 204 along the winding direction A2. The first electrode layer 202 may protrude from one side of the multilayer stack 20. The second electrode layer 203 may protrude from the other side of the multilayer stack 20 in the opposite direction to the first side. Contact portions 202a, 203a are thus formed.

[0105] Preferably, at least one, and preferably each, of the first and second electrode layers 202, 203 protrudes from the first insulating polymer layer and the separating layer in the longitudinal direction, over substantially at least 80% of their length and preferably over their entire length.

[0106] As an alternative or in addition to an offset of the electrode layers, it may be provided that the electrode layers include at least one and preferably several tabs which protrude from the first insulating polymer layer 201 and the separating layer 204 according to the winding direction A2.

[0107] According to one example, the edges of the lengths of the electrode layers 202, 203 protrude from the edges of the lengths of the first insulating polymer layer 201 by a distance dl, d6 substantially greater than 5 mm, preferably substantially greater than or equal to 10 mm.

[0108] The different layers of the stack 20 can be arranged in such a way as to limit the risk of contact between the electrode layers 202 and 203, and thus prevent a short circuit when an electric current is applied. For example, the electrode layer protruding on one side of the multilayer stack 20 can be set back from the separating layer 204 and / or the first insulating polymer layer 201 on the other side, as illustrated for example in [Fig. 0108]. This setback can correspond to the distance d3 and be greater than or equal to 5 mm

[0109] To this end, the length L1 along the Y direction of the first insulating polymer layer 201 and the separating layer 204 can be strictly greater than the length L2 of the electrode layers 202, 203. The risk of contact between the electrode layers 202, 203 once the multilayer stack 20 is wound is thus reduced. For example, the difference L1-L2 can be greater than or equal to 10 mm, preferably greater than or equal to 20 mm. The maximum length of the layers of the multilayer stack 20 can be greater than or equal to 50 cm, preferably greater than or equal to 70 cm.

[0110] For example, the width d2 of the first insulating polymer layer 201 may be greater than or equal to 40 mm, preferably greater than or equal to 50 mm. The separating layer 204 may further have at least a distance d4 strictly greater than the distance taken in the same direction of the first insulating polymer layer 200, for example d4 is greater than or equal to 5 mm.

[0111] The assembly can be subjected to a predetermined mechanical undertension to be in a fixed state of tension, for example between 1% and 5% (i.e., 1%, 2%, or 5%, for example), so as to reproduce the actual axial stress state of the cable as it may be experienced in a real cable, or when the cable expands during operation (the expansion of the cable core produces an axial tensile stress via the Poisson effects of the insulating material). The cable core can indeed reach 90°C.

[0112] The length of the separating layer 204 can be greater than the length of the insulating layer L1, especially if the separating layer is a polyimide adhesive. This helps to maintain the mechanical tension state of the winding.

[0113] The different layers of the multilayer stacking 20 are now described in more detail.

[0114] The first insulating polymer layer 201 is based on or made of an electrically insulating polymer used as an insulating material in high-voltage cables. This polymer may be a polymer from the family of extrudable and insulating thermoplastics, for example polyethylene (PE), polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), cross-linked polyethylene (PEr), ethylene propylene diene monomer rubber (EDPM), polyoxymethylene (POM), and in particular depending on the composition of the cable 1 whose aging is to be studied. Preferably, this polymer has: - a Young's modulus between 80 MPa and 200 MPa, and / or - flow thresholds below 20 MPa, and / or - strains at failure greater than 500%.

[0115] The polymer is thus particularly suited to form a 200 film by the trimming operation.

[0116] The insulating polymer layer comprises at least one portion based on an electrically insulating polymer for high-voltage cables. It may comprise a second portion based on a sheathing semiconductor material. The assembly under study may indeed include sheathing semiconductor material, and the electrical voltage applied during aging may be adapted accordingly.

[0117] The separator layer 204 can be a second layer of insulating polymer, for example, from the same film 200. Thus, the same trimming operation forms the interlayers between the electrode layers 202, 203. According to another example, the separator layer 204 is a layer based on, or made of, a polymer distinct from the polymer of layer 201. Preferably, the separator layer 204 is based on, or made of, polyimide. For very high voltage studies (typically for voltages greater than or equal to 100 kV), the insulator should be thicker than 100 µm to avoid breakdown. To also avoid increasing the thickness of the separator, a material High dielectric performance is preferable. Polyimide is a high-performance material, exhibiting a high relative electrical permittivity greater than 3.

[0118] The first insulating polymer layer 201 and / or the separating layer 204, preferably each of these layers, has a thickness el, taken along the X direction with reference to [Fig. 6A], of substantially between 50 µm and 200 µm, preferably a thickness of substantially between 70 µm and 150 µm, preferably substantially equal to 100 µm. These thicknesses are particularly suitable for reducing the voltage to be applied while maintaining a representative electromotive force. More specifically, the voltage applied to the assembly for the aging study should then be between 700 V and 20,000 V, for example greater than 5,000 V and / or less than 17,000 V.

[0119] For example, the insulation thickness of a 225,000 V cable is 20 mm, resulting in an electromotive force (EMF) E = 11,250,000 V / m. This EMF is the unaccelerated EMF. Maintaining this same EMF, corresponding to the actual cable conditions, if we consider an insulation thickness of 70 µm, 787.5 V must be applied to obtain the same EMF. For 100 µm thickness, 1,125 V, and for 150 µm, 1,687.5 V. For the aging test, there is an acceleration factor that depends on the high voltage selected for the aging study, typically 10,000 V. With an acceleration factor of 10, we arrive at 16,875 V for a 150 µm film.

[0120] The electrode layers 202, 203 can be made of metal, and preferably of aluminum. These layers can have a thickness a2, taken along the X direction with reference to [Fig. 6A], of substantially between 10 pm and 20 pm.

[0121] When the insulating polymer layer is subjected to mechanical tension, preferably the assembly prior to winding is also subjected to mechanical tension. To achieve this, a removable spray adhesive, such as Post-it note adhesive, can be applied to the face in contact with the insulating polymer layer to generate mechanical tension in the electrodes while simultaneously allowing for sliding to prevent tearing of the electrode layers.

[0122] The multilayer stack 20 is wound around itself about direction A2 to obtain the assembly 2, for example, illustrated in [Fig. 7]. The assembly 2 may comprise at least two turns, and preferably at least five turns, of the multilayer stack 20. This will depend, for example, on the diameter of the insulating support 21. The insulating support may be a polypropylene tube, for example, with a diameter of 16 mm. After winding, the assembly may have a diameter of approximately 25 mm, i.e., 6 stacks. The aim is to minimize the number of stacks to limit winding defects that could cause premature aging of the capsules.

[0123] This winding can be done on a winder, for example a semi-automatic one, and preferably a winder capable of managing the mechanical tension of the layer The insulating polymer layer provides insulation against several percent deformation (between 1% and 10%). The stack can be tensioned to replicate the axial stress state of the cable. This tensioning can be achieved using a weight or a roller tensioner when winding on a roller bed.

[0124] Preferably, the winding is configured to respect the inside / outside direction of portion 200a in the original cable 1. Since the end of portion 200a is originally positioned towards the inside of assembly 2, it will thus be wound first to be positioned inside assembly 2. The aging study will therefore be more representative of the original cable 1.

[0125] During cable winding, the multilayer stack 20 can be exposed to conditions corresponding to the desired aging study conditions. For example, the atmosphere can be controlled during winding. The humidity level and / or the presence of oxygen can be controlled. For example, an anhydrous atmosphere can be used to simulate buried high-voltage cable conditions. An oxygen-free atmosphere with a high humidity level could be used to simulate submarine high-voltage cable conditions. To simulate buried cable conditions, the atmosphere will be inert (e.g., argon-filled) with a specific humidity level. To simulate overhead cable conditions, the atmosphere will be air containing humidity.

[0126] The assembly 2 may further include a support 21, for example an electrically insulating support. This support may allow the winding of the multilayer stack 20, as well as its handling. The support 21 may have a transverse dimension d7, for example a diameter, taken along the Y direction with reference to [Fig. 7], greater than or equal to 15 mm, preferably substantially equal to 16 mm.

[0127] According to one example, assembly 2 has a diameter, taken along the Y direction with reference to [Fig.7], greater than or equal to 20 mm, preferably substantially equal to 24 mm.

[0128] As illustrated for example in [Fig. 8], the assembly 2 can be placed in a capsule 30 configured to electrically supply the assembly 2. This creates a cell 3. For this purpose, the capsule 30 comprises a body 301, a first plug 301 and a second plug. These elements define a closed internal volume 303 in which the assembly 2 is received.

[0129] Capsule 30 is now described in more detail with reference to [Fig.8].

[0130] Inside the enclosed volume 303, two electrodes 304, 305 can be arranged so as to each connect a separate electrode layer 202, 203 of the assembly 2. The capsule 30 can be configured to electrically connect the two electrodes 304, 305 to an external power supply. According to a For example, electrodes 303, 304 are arranged on either side of the internal volume 303 along the Z direction, or equivalently along the winding direction A2 of the assembly 2. Each electrode can be configured to be compressed against the ends 2a, 2b of the assembly 2, illustrated in [Fig. 7], and more particularly the contact portions 202a, 203a. Electrodes 304, 305 are, for example, made of aluminum.

[0131] Each plug 301, 302 may be electrically conductive, for example made of metal, and in electrical contact, preferably in direct contact, with the corresponding electrode 304, 305. Re-establishing contact at the capsule 30 is thus facilitated. The plugs 301, 302 may be made of stainless steel, or preferably based on or made of copper or copper alloys (for example, brass).

[0132] The body 300 of the capsule 30 may include a first electrically insulating sleeve 300a laterally surrounding the assembly 2 in the (x,y) plane. Preferably, the first sleeve extends along the Z direction over a length dlO substantially equal to the combined length of the electrodes 304, 305 and the assembly 2. dlO may be greater than or equal to 60 mm, preferably approximately equal to 66 mm. The first sleeve 300a may have a transverse dimension taken along the Y direction with reference to [Fig. 8], for example, an inner diameter greater than or equal to 20 mm, preferably approximately equal to 26 mm.

[0133] The body 300 of the capsule 30 may further comprise a second sleeve 300b, for example metallic, laterally surrounding the first sleeve 300a. The second sleeve 300b may extend over the first and second plugs 301, 302. According to one example, the second sleeve 300b is in electrical contact with the second plug 302. Preferably, the second sleeve 300b is made of copper. Thermal conduction through the second sleeve 300b is thus improved. The exposure of the assembly 2 to thermal stress is thereby improved during aging studies.

[0134] The body 300 of the capsule 30 may further comprise an electrically insulating collar 306 configured to separate the first cap 301 from the second sleeve 300b. The collar 306 may be arranged around the first sleeve 300a. The collar 306 and the first sleeve 300a may, for example, form a single unit.

[0135] The first sleeve 300a and the collar 306 may be based on or made of an electrically insulating polymer, preferably polyetheretherketone (commonly referred to as PEEK from the English PolyEtherEtherKeton).

[0136] Preferably, the capsule 30 is configured to define the enclosed internal volume 303 in a hermetically sealed manner. The assembly 2 can thus be placed under a controlled atmosphere, as described previously, in capsule 30 in order to maintain the conditions desired for the study of aging.

[0137] For this purpose, the second plug 302 can be joined to the body 300, and more particularly to the second sleeve 300b, by brazing. The first plug 301 can cooperate with the body 300, and more particularly with the first sleeve 300a, by screwing with complementary threads.

[0138] The first plug 300 can therefore be screwed onto the body 300 until a watertight seal is obtained to close the enclosed volume 303. For this purpose, one or more seals 307, for example annular seals, can be arranged at the collar 306. The seals 307 can be arranged on either side of the collar 306 in the direction Z. Thus, the first plug 301 comes against a sealing seal 307 and pushes the collar 306 against the second sleeve 300b by means of a second sealing seal 307.

[0139] One or preferably several cells 3 can be arranged in a housing 40 to form a system 4. The housing 40 is now described in more detail with reference to [Fig. 9]. The housing 40 is configured to supply electrical power to the cells 3.

[0140] For this purpose, the housing 40 may include a body 400 comprising at least one and preferably several compartments 400a, 400b, 400c, 400d, 400e. Each compartment may be configured to accommodate a cell 3, and preferably a single cell 3. The body 400 may be based on, or made of, an electrically insulating material. As an example, the body 400 is made of Bakelite. Thus, the body is electrically insulating and heat-resistant. This is therefore particularly advantageous for studying the aging of a cable 1 under thermal stress.

[0141] The housing 40 can be configured to accommodate a number of cells 3 greater than or equal to 50, and preferably greater than or equal to 100. According to one example, the body 400 forms a matrix of housings to accommodate the cells 3, for example a 10 x 10 matrix. The system 4 thus allows the study of a large number of assemblies 2 in parallel.

[0142] The housing 40 may further include at least one cover configured to electrically connect the cells 3 to some kind of external power supply 5.

[0143] The housing 40 may include a first cover 401 configured to electrically connect each cell 3 in isolation from the other cells 3. Thus, the electrical properties of each cell 3 can be tested individually. For this purpose, the first cover 401 may include several electrical connectors 401a. Each electrical connector 401a can be configured to form an electrical connection for a given cell 3. In the cover 401, the electrical connectors 401a are not electrically connected to each other. 401a electrical connectors can be separated from each other by an electrically insulating material, for example bakelite.

[0144] The housing 40 includes a second cover 402 configured to connect the electrical connectors 401a of the first cover 401 to the external power supply 5, for example, as illustrated in [Fig. 10]. The second cover 402 thus allows for re-establishment of contact at the connectors 401a of the first cover 401 and parallel connection of the cells 3. For this purpose, the second cover 402 may include an electrical connector 402a configured to electrically connect the connectors 401a of the first cover 401 together. The electrical connector 402a may be configured to be electrically connected to the external power supply 5. Except for its parts in contact with the electrical connectors 401a and the portion connecting to the external power supply 5, the electrical connector 402a may be electrically insulated from its environment by an electrically insulating material, for example, Bakelite.

[0145] The housing 40 may further include a base 403 configured to electrically connect each cell 3 so as to close the electrical circuit with the external power supply 5. For this purpose, the base 403 may include an electrical connector 403a configured to electrically connect the cells 3 together. The electrical connector 403a may be configured to be electrically connected to the external power supply 5. Except for its parts in contact with the cells 3, the electrical connector 403a may be electrically insulated from its environment by an electrically insulating material, for example, Bakelite.

[0146] The electrical connectors 401a, 402a, 403a of the housing 40 are preferably made of copper.

[0147] Some dimensions of the housing 40 are now given; dl1 is preferably greater than or equal to the height of a cell along the z-direction, and preferably approximately equal to 100 mm. dl2, dl3, and dl4 may be equal, for example, approximately equal to 15 mm. The housing may have a width in y and a depth in x approximately equal to 400 mm. The housings 400a, 400b... may be spaced at a distance along x and / or y approximately equal to 10 mm.

[0148] The method for studying the aging of a high-voltage cable 1 is now described. This method can implement the various objects described previously. More particularly, the method can include exposing at least one assembly 2 to an electric current, and preferably several assemblies 2. The electric current can be alternating or direct, depending on the type of high-voltage cable 1 and / or the desired aging conditions. The electric current can have a voltage between 5,000 V and 20,000 V, preferably between 10,000 V and 20,000 V. The external power supply 5 can be configured to generate this current. For example, the power supply 5 is a high-voltage generator. This electrical current can be supplied to assembly 2 via system 4 and the various electrical connectors linking the external power supply 5 to cell 3 and thus assembly 2. The external power supply 5 and the regulated enclosure can be part of system 4.

[0149] In addition to exposure to an electric current, the study method may include exposing the assemblies 2 to thermal stress, for example, a temperature greater than or equal to 60°C, and / or mechanical stress. For this purpose, the system 4 can be placed in a temperature-controlled chamber 7, as illustrated in [Fig. 10]. The choice of temperature depends on the duration of the study. The lower the temperature, the lower the acceleration and therefore the slower the aging. 60°C is the minimum temperature for the cable insulating material, as it is the temperature at which a mechanical transition occurs that promotes macromolecular mobility in the insulating material (thus accelerating diffusion and the chemical reactions of aging). This study temperature preferably remains below the melting temperature of the polymer of interest.

[0150] To study the aging of the assemblies 2, the method may include at least one measurement of an electrical property, and in particular the internal resistance, of the assemblies 2. For this purpose, in the system 4, the second cover 402 of the housing 40 can be removed. The internal resistance of an assembly 2 can be measured via the corresponding connector 401a. The variability between the different cells 3 can therefore be analyzed in situ while minimizing the handling of the assemblies 3.

[0151] The study method may include the study of assemblies 2 greater than or equal to 50 and preferably greater than or equal to 100. This is particularly advantageous given the duration of aging studies, which can, for example, last up to five years. In the same study, the study conditions may differ between different cells 3, for example, the humidity level and / or the presence or absence of oxygen. Airtight capsules 30 are particularly advantageous for this purpose. The aging study can therefore take into account a greater number of variables for predicting the service life of the high-voltage cable. In the same study, several assemblies 2 from the same high-voltage cable can be studied under the same conditions. This improves the statistical power of the study and thus enhances the clarity of the results.In the 40 box, several assemblies 2 from different high-voltage cables can be studied, under the same atmospheric conditions or not.

[0152] The invention is not limited to the embodiments described above and extends to all embodiments covered by the invention. The present invention is not limited to the examples described above. Many other embodiments are possible, for example by combining features described above, without departing from the scope of the invention. Furthermore, the features described with respect to one aspect of the invention can be combined with another aspect of the invention.

Claims

Demands

1. A method for manufacturing an assembly (2) for studying the aging of a high-voltage cable (1), the method comprising: • the formation of a multilayer stack (20) comprising the at least partial superposition of: • a first layer called the electrode layer (202), based on an electrically conductive material, • at least one layer based on an electrically insulating polymer, called the first insulating polymer layer (201), • a second layer called the electrode layer (203), based on an electrically conductive material, such that the first insulating polymer layer (201) is disposed between the first (202) and second (203) electrode layers, and • a separating layer (204) at least partially superimposed with the assembly formed by the first (202) and second (203) electrode layers and the first insulating polymer layer (201),• a winding of the multilayer stack (20) at least partially around itself around a longitudinal direction (A2) to form the assembly (2).

2. A method according to the preceding claim, further comprising: • supplying a portion (10) of high-voltage cable (1) comprising a core (11) extending along a main extension direction (Al) of the cable (1) and surrounded around said direction by a material (13) based on the electrically insulating polymer, • forming a film (200) based on the electrically insulating polymer, by trimming the portion (10) of high-voltage cable (1) around the main extension direction (Al) of the cable (1), at least a portion (200a) of the film (200) being used during the formation of the multilayer stack (20).

3. A method according to any one of the preceding claims, comprising, prior to the formation of the film (200), aging of the high-voltage cable (1) comprising exposing the portion (10) of cable (1) to an electric current, and / or wherein the portion (10) of cable (1) is derived from a previously used high-voltage cable (1).

4. A method according to any one of the preceding claims, wherein the winding of the multilayer stack (20) is carried out under an atmosphere of controlled humidity and / or controlled oxygen level.

5. A method according to any one of the preceding claims, further comprising, prior to the formation of the multilayer stack (20), a selection of the portion (200a) of the film (200) to form the multilayer stack (20), according to a corresponding position of the electrically insulating polymer-based material in the high-voltage cable (1).

6. A method according to any one of the preceding claims, comprising, before the formation of the film (200): • straightening of a lateral perimeter (100) of the portion (10) of cable (1), and / or • straightening of at least one end (10a, 10b) of the portion (10) of cable (1).

7. Assembly (2) for studying the aging of a high-voltage cable (1), characterized in that the assembly (2) comprises a multilayer stack (20) at least partially wound around itself around a longitudinal direction (A2), the multilayer stack (20) comprising: • a first (202) and a second (203) layer, referred to as electrodes, based on an electrically conductive material, • a first layer based on a polymer that electrically insulates the high-voltage cable whose aging is to be studied, referred to as the first insulating polymer layer (201), and disposed between the first (202) and second (203) electrodes, and • a separating layer (204) configured to electrically insulate the first (202) and second (203) layers of electrodes between them, in the wound multilayer stack (20).

8. Assembly (2) according to the preceding claim, wherein at least one of the first (202) and second (203) electrode layers protrudes at least partially from the first insulating polymer layer (201) and the separator layer (204) in the longitudinal direction (A2).

9. Assembly (2) according to the preceding claim, wherein the first (202) and second (203) electrode layers are arranged offset from the first insulating polymer layer (201) and the separator layer (204) along the longitudinal direction (A2), such that: • the first electrode layer (202) extends beyond the first insulating polymer layer (201) and the separator layer (204) on a first side (20a) of the multilayer stack (20) with respect to the longitudinal direction (A2), without extending beyond a second side (20b) of the multilayer stack (20) opposite the first side (20a), • the second electrode layer (203) extends beyond the first insulating polymer layer (201) and the separator layer (204) on the second side (20b) of the multilayer stack (20), without extending beyond the first side (20a).

10. Assembly (2) according to any one of the three preceding claims, wherein the first insulating polymer layer (201) has a thickness between 50 pm and 200 pm.

11. Assembly (2) according to any one of the four preceding claims, wherein the separating layer (204) is a second layer based on the electrically insulating polymer of high-voltage cable, referred to as the second insulating polymer layer (204a).

12. Assembly (2) according to any one of claims 7 to 10, wherein the separating layer (204b) is a polyimide-based layer.

13. Cell (3) for studying the aging of a high-voltage cable (1), comprising: • the assembly (2) according to any one of claims 7 to 12, and • a capsule (30) configured to electrically supply the assembly (2), the capsule (30) comprising: • a body (300), a first plug (301) and a second plug (302), defining a closed internal volume (303), the capsule (30) being configured to receive the assembly (2) in the closed internal volume (303), • two electrodes (304, 305) each configured to connect an electrode layer (202, 203) separate from the assembly (2).

14. Cell (3) according to the preceding claim, wherein the body (300) and the first (301) and second (302) plugs are configured to define the closed internal volume (303) in a hermetically sealed manner.

15. Cell (3) according to any one of the two preceding claims, wherein, in the assembly (2), at least one of the first (202) and second (203) electrode layers protrudes at least partially from the first insulating polymer layer (201) and the separator layer (204) in the longitudinal direction (A2), so as to be in electrical contact with the corresponding electrode (304, 305) of the capsule (30), disposed opposite said electrode layer (202, 203).

16. Cell (3) according to any one of the three preceding claims, wherein each stopper (301, 302) is electrically conductive and is electrically connected with an electrode (304, 305) of the capsule (30), and wherein the body (300) of the capsule (30) is configured to electrically isolate the first (301) and second (302) stoppers from each other.

17. Cell (3) according to the preceding claim, wherein the body (300) of the capsule (30) comprises: • a first electrically insulating sleeve (300a) laterally surrounding the assembly (2), • a second metallic sleeve (300b) laterally surrounding the first sleeve (300a), the second sleeve being in electrical contact with the second cap (302), and • an electrically insulating collar (306) separating the first plug (301) from the second sleeve (300b).

18. System (4) comprising several cells (3) according to the five preceding claims and a housing (40) configured to receive and electrically supply the cells (3).

19. System (4) according to the preceding claim, comprising a number of cells (3) greater than or equal to 50, preferably greater than or equal to 100.

20. System (4) according to any one of the two preceding claims, wherein the housing (40) comprises: • a first cover (401) comprising several electrical connectors (401a), the electrical connectors (401a) being configured to each electrically connect at least one cell (3), separately from the at least one cell (3) connected by the other electrical connectors (401a), and • a second cover (402) configured to electrically connect together the electrical connectors (401a) of the first cover (401) to an external power supply (5).

21. A method for studying the aging of a high-voltage cable (1) comprising: • exposing at least one assembly (2) according to any one of claims 7 to 12 to an electric current, • at least one measurement of an electrical property, and for example of the internal resistance, of at least one assembly (2) so as to obtain a data representative of the aging of a high-voltage cable (1).

22. A method according to the preceding claim, wherein the electric current has a voltage between 700 V and 17,000 V.

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