Longitudinal cable for the transmission of electrical power, Propulsion chain for aircraft and associated process

Abstract

A longitudinal cable (10) comprising a first conductor (1), a first semiconductor layer (2), a first insulation layer (3), the first conductor (1) comprising a plurality of conductive wires (4) each comprising a conductive strand (40) which is covered with an insulation sheath (41), the first conductor (1) comprising at least one discontinuous longitudinal groove at the periphery exposing the conductive strand (40) of the conductive wires (4) at a contact zone (ZC), each exposed conductive strand (40) being a smoothing conductive strand (5), each smoothing conductive strand (5) comprising longitudinal portions covered with an insulation sheath (51) and exposed longitudinal portions, the exposed longitudinal portions (P2) being in contact with the first semiconductor layer (2) at the contact zone (ZC), the contact zones (ZC) being spaced apart by the same contact pitch. Abstract figure: Figure 5

Description

Title of the invention: Longitudinal cable for transporting electrical power, Propulsion chain for aircraft and associated method Technical field

[0001] The present invention relates to the field of transmission of electrical power through a cable, in particular, for an aeronautical application.

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various States. In particular, an ambitious standard applies both to new types of aircraft and those in circulation requiring the implementation of technological solutions in order to make them compliant with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0003] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] This sustained research and development work covers new generations of aircraft engines, the lightening of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as essential complements to technological progress, aeronautical biofuels.

[0006] An electric or hybrid aircraft conventionally comprises a propulsion chain comprising electric motors which must be electrically powered with high power, that is to say, with a high voltage (230V-3000V) at high frequency (400Hz-3000Hz) with a high intensity (100A-1000A).

[0007] For this purpose, the propulsion chain comprises a plurality of longitudinal cables which are distributed throughout the aircraft in order to connect different electrical equipment. The electrical equipment is for example in the form of generators, power electronic devices, electric motors, etc.

[0008] A cable must be able to carry high power but also have a reduced size and mass to allow its integration into an aircraft without penalizing its energy consumption. To this end, with reference to [Fig.l], a cable of the “coaxial” type 100 is known in the prior art which extends longitudinally along an axis XI and which comprises: • a first conductor 101, • a first semiconductor layer 102 surrounding the first conductor 101, • an insulation layer 103 surrounding the first semiconductor layer 102, • a second semiconductor layer 104 surrounding the insulation layer 103, and • two insulating protective sheaths 105, 106.

[0009] In practice, when an alternating current or a pulse width modulated current is flowing, the cable 100 heats up more significantly for conductor size conditions compared to the electrical frequency of the current due to phenomena known as "skin effect" and proximity effect. Also, to avoid the risk of undesirable heating, it is necessary to limit the transmitted power by reducing, for example, the intensity of the current or to reduce the electrical resistance of the conductor by increasing, for example, the size of the conductor.

[0010] In order to eliminate this drawback, with reference to [Fig. 2], a cable of the “Litz” type 200 is known in the prior art, which extends longitudinally along an axis X2, comprising several conductive wires 210 which are electrically insulated from each other. Each conductive wire 210 comprises a conductive strand 211 which is covered with an insulating sheath 212. The conductive wires 210 are twisted in order to form the conductor which can then be protected by insulating protective sheaths 202, 203. Advantageously, the electric current can flow in a balanced manner in each conductive strand 211.

[0011] A Litz 200 type cable does not allow the electric field to be contained in a way as secure as a coaxial cable 100. Indeed, in a cable of the “coaxial” type 100, the semiconductor layer 102 makes it possible to smooth the electric field coming from the first conductor 101. The presence of the semiconductor layers 102 and 104 on either side of the insulation layer 103 makes it possible to contain in a manner optimal electric field inside the insulation layer 103.

[0012] To smooth the electric field coming from a conductor 101, it is necessary for the semiconductor layer 102 to be at the same electrical potential as said conductor 101. Also, the use of a semiconductor layer 102 cannot be used with a cable of the Litz 200 type given that the conductive wires 210 are electrically insulated from each other and therefore cannot be in electrical contact with the environment.

[0013] The invention thus aims to eliminate at least some of these drawbacks by proposing a cable for the transport of electrical power which makes it possible to avoid any risk of additional heating by "skin effect" and proximity effect while making it possible to increase electrical safety.

[0014] Although the invention was originally born for a cable of the "coaxial" type, the present invention also applies to a simple cable whose insulation has at least one layer of semiconductor. PRESENTATION OF THE INVENTION

[0015] The invention relates to a longitudinal cable for the transmission of electrical power, the longitudinal cable comprising: • A first driver, • A first layer of semiconductor surrounding the first conductor, • A first layer of insulation surrounding the first layer of semi- driver, • the first conductor having a periphery in contact with the first semiconductor layer, the first conductor comprising: • a plurality of conductive wires each comprising a conductive strand which is covered with an insulating sheath so that the conductive strands are electrically insulated from each other, • the first conductor comprising at least one discontinuous longitudinal groove at the periphery exposing the conductive strand of the conductive wires at a contact zone, each exposed conductive strand being a smoothing conductive strand, each smoothing conductive strand comprising longitudinal portions covered with an insulating sheath and exposed longitudinal portions, the exposed longitudinal portions being in contact with the first semiconductor layer at the contact zone so that the first semiconductor layer has the same electrical potential as the smoothing conductive strand, the contact zones being spaced apart by the same contact pitch.

[0016] Advantageously, a cable is obtained which allows, on the one hand, optimal smoothing of the electric field and, on the other hand, minimal heating by "skin effect" and proximity effect. Advantageously, one or more smoothing conductors are used to conduct power and to equalize the electric potential (equipotentiality) while the other conductive strands are insulated so as to reduce the skin effect and the proximity effect. The cable obtained has a limited mass and a restricted size. The cable is perfectly suited for the transport of high power of the alternating or PWM (Pulse Width Modulation) type at high altitude. This makes it possible to increase the performance of the electrical insulation by reducing partial discharge phenomena, local reinforcement phenomena of the electric field, space charge phenomena and electrical aging of the insulation layer.Advantageously, the smoothing conductive strand is partially covered with an insulating sheath so as to limit the skin effect and allow equalization of the electrical potential. Advantageously, the risk of heating by internal contact of two smoothing conductive strands can be advantageously avoided.

[0017] Advantageously, a smoothing conductive strand is a conductive wire from which the insulating sheath has been partially removed. This is particularly advantageous since it is sufficient to form a discontinuous longitudinal groove on a first conductor formed from only conductive wires. The contact areas are thus formed in a practical, regular and precise manner.

[0018] According to one aspect, the first conductor comprises at least two smoothing conductive strands, preferably at least three. According to one aspect, the first conductor comprises less than five smoothing conductive strands. According to one aspect, the number of smoothing conductive wires is greater than 10, preferably greater than 20.

[0019] The use of several smoothing conductive strands makes it possible to equalize the electrical potential of the first semiconductor layer according to several contact zones. The equalization of the electrical potential is thus more homogeneous and efficient. The use of a limited number of smoothing conductive strands makes it possible to limit the skin effect and the proximity effect likely to generate heating.

[0020] According to one aspect, the first conductor having a periphery, the smoothing conductive strands are distributed angularly at the periphery of the first conductor. This makes it possible to distribute the contact areas. The equalization of the electrical potential is thus more homogeneous and efficient.

[0021] According to one aspect, the smoothing conductive strand has the same cross-section as a conductive strand of a conductive wire. This advantageously makes it possible to conduct electrical power homogeneously.

[0022] According to one aspect, the smoothing conductive strand is a conductive strand of a conductive wire. The strands thus have the same characteristics for transporting electrical power.

[0023] According to one aspect, the first conductor comprising at least one strand of conductive wires twisted with a twist pitch which is constant, the contact pitch being a multiple of the twist pitch. This makes it possible to keep the insulated contact wire inside a strand.

[0024] According to one aspect, the contact pitch is equal to the twist pitch. This makes it possible to maximize smoothing.

[0025] According to one aspect, the cable comprises at least two discontinuous longitudinal grooves, preferably, and at least three longitudinal grooves. The equalization of the electrical potential is thus more homogeneous and efficient.

[0026] According to one aspect, the exposed portions are obtained by abrasion of the insulation sheath of the conductive strand of the conductive wire.

[0027] In one aspect, the cable comprises at least one strand of conductive wires, preferably a plurality of strands of conductive wires. A strand allows the position of the conductive wires to be varied in a cross-section so that a conductor wire is located at the periphery periodically. The magnetic fields are further balanced. The conductive wires alternate between an inner position and an outer position.

[0028] According to one aspect, the strand comprises at least one smoothing conductive strand assembled with the conductive wires which are by nature insulated.

[0029] According to one aspect, the cable comprises: • A second layer of semiconductor surrounding the first layer of insulation and • A second conductor surrounding the second semiconductor layer.

[0030] This makes it possible to form a “coaxial” cable having a “skin effect” and a proximity effect which is reduced. Significant electrical power can be transmitted with increased electrical safety.

[0031] The invention also relates to a propulsion chain for aircraft comprising a plurality of electrical equipment connected by at least one power cable as presented previously.

[0032] The invention also relates to an aircraft comprising a propulsion chain as presented previously.

[0033] The invention also relates to a method of manufacturing a longitudinal cable for the transmission of electrical power, the method comprising steps consisting of: Providing a first conductor comprising a plurality of conductive wires each comprising a conductive strand which is covered with an insulating sheath so that the conductive strands are electrically insulated from each other • Form at least one discontinuous longitudinal groove at the periphery exposing the conductive strand of the conductive wires at a contact zone, each exposed conductive strand being a smoothing conductive strand, each smoothing conductive strand comprising longitudinal portions covered with an insulating sheath and exposed longitudinal portions, • Surround the first conductor with a first layer of semiconductor so that the exposed longitudinal portions are in contact with the first layer of semiconductor at the contact zone so that the first layer of semiconductor has the same electrical potential as the smoothing conductive strand, the contact zones being spaced apart by the same contact pitch, • Surround the first layer of semiconductor with a first layer of insulation.

[0034] According to one aspect, the method comprises a step of twisting the conductive wires and the at least one smoothing conductor to obtain the first conductor.

[0035] According to one aspect, the method comprises a step of twisting conductive wires to obtain the first conductor and a step of forming at least one discontinuous longitudinal groove uncovering the at least one conductive strand of the conductive wires at the periphery of the first conductor, each uncovered conductive strand being a smoothing conductive strand.

[0036] The twisting step is preferably carried out only with conductive wires.

[0037] According to one aspect, the step of forming the at least one discontinuous longitudinal groove is carried out by abrasion of the insulation sheath of the conductive wires. PRESENTATION OF FIGURES

[0038] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0039] [Fig.l] is a schematic representation of a coaxial cable according to the prior art.

[0040] [Fig.2] is a schematic representation of a Litz cable according to the prior art.

[0041] [Fig.3] is a schematic representation of an aircraft with cables of power transmission.

[0042] [Fig. 4] is a schematic representation of a section of a longitudinal cable according to an embodiment of the invention with a single conductive strand of smoothing.

[0043] [Fig.5] is a close-up schematic representation of [Fig.4].

[0044] [Fig.6] is a schematic representation of a section of a longitudinal cable according to one embodiment of the invention with several smoothing conductive strands.

[0045] [Fig.7] is a schematic cross-sectional representation of a first conductor in which the twisting of the smoothing conductive strand is shown.

[0046] [Fig.8] is a schematic representation from above of the first conductor of [Fig.7].

[0047] [Fig.9] is a close-up schematic cross-sectional representation of a smoothing conductive strand according to a first embodiment.

[0048] [Fig. 10] is a schematic cross-sectional representation of a first conductor in which the twisting of the smoothing conductive strand is shown.

[0049] [Fig. 11] is a schematic representation of a device for abrading a first conductor to form three discontinuous longitudinal grooves.

[0050] [Fig. 12] is a schematic representation of the first conductor with a discontinuous longitudinal groove.

[0051] [Fig. 13] is a schematic representation of the abrasion device of [Fig. 11] seen in a plane transverse to the axis of the first conductor.

[0052] [Fig.14] is a schematic representation of the abrasion device of [Fig.11] seen in a plane lateral to the axis of the first conductor.

[0053] [Fig. 15] is a close-up schematic cross-sectional representation of a smoothing conductive strand according to a second embodiment.

[0054] [Fig. 16] is a schematic representation of a section of a longitudinal cable with a single smoothing conductive strand according to the second embodiment.

[0055] [Fig. 17] is a close-up schematic representation of [Fig. 16].

[0056] [Fig. 18] is a schematic representation of a coaxial cable with a single smoothing conductive strand.

[0057] [Fig. 19] is a schematic representation of a coaxial cable with several smoothing conductive strands.

[0058] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0059] The invention relates to a longitudinal cable for the transmission of electrical power, in particular, in the aeronautical field. It goes without saying that the invention also applies to other technical fields such as industry, maritime, railway, etc.

[0060] With reference to [Fig. 3], there is shown an aircraft 300 comprising a propulsion chain 301 comprising a plurality of electrical equipment E1-E3 connected by a plurality of power cables 10. The electrical equipment E1-E3 is for example in the form of generators, electronic power devices, electric motors, etc.

[0061] The longitudinal cable 10 is configured to carry high power, in particular, high voltage (230V-3000V) at high frequency (400Hz-3000Hz) with high current (100A-1000A). Such a longitudinal cable 10 is suitable for powering an electric propulsion motor.

[0062] Referring to Figures 4 and 5, there is shown a sectional view of an embodiment of a longitudinal cable 10 for transporting electrical power. The longitudinal cable 10 extends along an axis X shown in [Fig.7].

[0063] As illustrated in Figures 4 and 5, the longitudinal cable 10 comprises a first conductor 1, a first semiconductor layer 2 surrounding the first conductor 1, and a first insulation layer 3 surrounding the first semiconductor layer 2. The longitudinal cable 10 is thus a simple cable as opposed to a coaxial cable which will be presented later.

[0064] The first semiconductor layer 2 is formed around the first conductor 1 and is configured to form a screen for smoothing the electric field coming from the first conductor 1. Preferably, the first semiconductor layer 2 is made of polymer insulating material of the perfluoroalkoxy (PFA) type, fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), silicones, fluoro-silicones, rubbers, thermosets or thermoplastics of the polyetheretherketone (PEEK) type or others, or bio-sourced materials comprising additives which make it possible to modify their electrical properties, such as for example carbon black, nanoparticle, metallic fillers to provide controlled electrical conductivity.

[0065] The first insulation layer 3 surrounding the first semiconductor layer 2 is configured to provide electrical insulation. Preferably, the first insulation layer 3 is made of a polymer insulating material of the perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE) type, silicones, fluorosilicones, rubbers, thermosets or thermoplastics of the polyetheretherketone (PEEK) type or others, or bio-sourced. Preferably, it will be made of the same insulating material as the semiconductor layer but will be free of conductive fillers. In order for the first insulation layer 3 to perform its function optimally, it is important that the first semiconductor layer 2 ensures efficient smoothing of the electric field from the first conductor 1. The first conductor 1 has a periphery which is configured to be in contact with the first semiconductor layer 2.

[0066] As illustrated in Figures 4 and 5, the first conductor 1 comprises a plurality of conductive wires 4 each comprising a conductive strand 40 which is covered with an insulating sheath 41 so that the conductive strands 40 are electrically insulated from each other. The conductive wires 4 are thus “Litz wires” and make it possible to reduce the skin and proximity effect which leads to local heating. A conductive strand 40 may comprise one or more electrical wires.

[0067] In this example, the conductive strand 40 is made of a conductive material of the copper, aluminum, alloys or equivalent type, preferably copper. The conductive strand 40 has a diameter of between 0.008 mm and 3 mm. The insulating sheath 41 is made of enamel, varnish or thermoplastics or equivalent, preferably of enamel or varnish Polyurethane (PUR), Polyesterimides (PES), Polyesterimide (PEI), Polyamideimide (PAI), simple Polyimides (PI), aromatic Polyimides, or even perfluoroalkoxy (PFA) or polyetheretherketone (PEEK) thermoplastics. The insulating sheath 41 has a thickness of between 0.001 mm and 0.05 mm.

[0068] As illustrated in [Fig.5], the first conductor 1 further comprises at least one smoothing conductive strand 5 in contact with the first semiconductor layer 2 along at least one contact zone ZC so that the first semiconductor layer 2 has the same electrical potential as the smoothing conductive strand 5. The electrical power is transmitted by the conductive strands 40 of the conductive wires 4 but also by the smoothing conductive strand(s) 5.

[0069] Thus, certain power conductors, called smoothing conductive strands 5, are in contact with the first semiconductor layer 2 so as to allow the first semiconductor layer 2 to smooth the electric field coming from the first conductor 1 and thus improve the electrical insulation implemented by the first insulation layer 3.

[0070] According to one aspect, with reference to Figures 4 and 5, the longitudinal cable 10 comprises at least one strand T4 of conductive wires 4, preferably a plurality of strands T4 of conductive wires 4. With reference to [Fig. 4], the conductive wires 4 and the smoothing conductive strand 5 are assembled and twisted together so as to form twists along the axis X of the longitudinal cable 10 as schematically illustrated in [Fig. 7]. In other words, at a given longitudinal position of the longitudinal cable 10, a conductive wire 4 and / or the smoothing conductive strand 5 is not located at the same position in a cross-section of the longitudinal cable 10. It nevertheless goes without saying that some conductive wires might not be twisted. The smoothing conductive strand(s) 5 are preferably all twisted. In a first conductor 1, the conductive wires 4 and the smoothing conductive strand(s) 5 may be twisted together in a single strand or assembled into elementary strands which are then themselves assembled and twisted to form an overall strand.

[0071] Preferably, the smoothing conductive strand 5 has the same section as a conductive strand 40 of a conductive wire 4. This advantageously allows each conductive strand 40, 5 to have similar characteristics, which improves the service life and facilitates the transport of electrical power.

[0072] With reference to Figures 7 and 8, there is shown schematically a smoothing conductive strand 5 which is twisted with a twisting pitch pt which is constant in the first conductor 1. At each twisting pitch pt, the smoothing conductive strand 5 is positioned at the periphery of the first conductor 1 in a periodic manner, that is to say, in contact with the first semiconductor layer 2 (not shown) according to a contact zone ZC. In this embodiment, the contact zones ZC are thus spaced longitudinally by a contact pitch pc which is equal to the twisting pitch pt. ​​As illustrated in [Fig.8], the contact zones ZC are spaced axially by the contact pitch pc.

[0073] According to a variant, the first conductor 1 may comprise several smoothing conductor strands 5 distributed angularly around the periphery of the first conductor 1. In [Fig. 6], three smoothing conductors 5 are advantageously provided, spaced angularly by 120°. In this example, the contact zones of the smoothing conductors 5 belong to the same plane in cross-section of the longitudinal cable 10. It is nevertheless preferable for the contact zones of different smoothing conductors 5 to belong to different planes so as to distribute the contact zones longitudinally and allow effective electrical potential setting of the first semiconductor layer 2.

[0074] With reference to [Fig.9], the smoothing conductive strand 5 comprises covered longitudinal portions PI with an insulating sheath 51 and uncovered longitudinal portions P2. In particular, the presence of covered longitudinal portions PI makes it possible to reduce the skin effect and the proximity effect and, consequently, heating. A higher electrical power can thus be transported.

[0075] According to a first variant, the smoothing conductive strand 5 is formed independently. Preferably, the conductive wires 4 and the smoothing conductive strand 5 are assembled and twisted together so as to form twists along the axis X of the longitudinal cable 10 as illustrated in [Fig. 12]. The uncovered longitudinal portions P2 are positioned at the periphery of the first conductor 1 so as to be in contact with the first semiconductor layer 2 according to a plurality of contact zones ZC. For this purpose, the contact zones ZC are thus spaced longitudinally by a contact pitch pc which is equal to a multiple of the twisting pitch pt. ​​For example, with reference to [Fig. 10], the contact pitch pc is equal to twice the no twisting pt. The contact pitch pc can be determined according to the specific constraints by specifying the position of the exposed longitudinal portions P2.

[0076] The first conductor 1 is produced by integrating one or more smoothing conductive strands 5 at the periphery of the conductive wires 4. The assembly can then be assembled and twisted in a conventional manner.

[0077] An example of implementation of a method for manufacturing a longitudinal cable 10 for transporting electrical power will now be presented.

[0078] The method comprises a step of providing a first conductor 1 comprising a plurality of conductive wires 4 each comprising a conductive strand 40 which is covered with an insulating sheath 41 so that the conductive strands 40 are electrically insulated from each other and at least one smoothing conductive strand 5 located at the periphery of the first conductor 1.

[0079] The method comprises a step of assembling and twisting conductive wires 4 and the at least one smoothing conductor 5 to obtain the first conductor 1. The smoothing conductor 5 is a conductor comprising covered portions PI and uncovered portions P2.

[0080] The method comprises a step of surrounding the first conductor 1 with a first semiconductor layer 2 so that an uncovered portion P2 is in contact with the first semiconductor layer 2 along at least one contact zone ZC so that the smoothing conductive strand 5 has the same electrical potential as the first semiconductor layer 2. The method comprises a step of surrounding the first semiconductor layer 2 with an insulation layer 3. Preferably, this is carried out simultaneously by coextrusion.

[0081] This advantageously provides a “simple” longitudinal cable 10 allowing the transport of electrical power which makes it possible to avoid any risk of heating by “skin effect” and proximity effect while allowing smoothing of the electric field in order to increase electrical safety. The mass is reduced as well as the size.

[0082] In practice, it is complex to achieve optimal twisting so that the exposed longitudinal portions P2 are positioned precisely at the periphery of the first conductor 1 to come into contact with the first semiconductor layer 2 at a contact pitch pc. According to a variant, the smoothing conductive strand 5 is a conductive wire 4 of a strand of conductive wires 4 whose insulating sheath 41 has been removed locally in a precise and regular manner.

[0083] An example of implementation of a method for manufacturing a longitudinal cable 10 for transporting electrical power will now be presented.

[0084] The method comprises a step of providing a first conductor 1 comprising a plurality of conductive wires 4 each comprising a conductive strand 40 which is covered with an insulating sheath 41 so that the conductive strands 40 are electrically insulated from each other and at least one smoothing conductive strand 5 located at a periphery of the first conductor 1.

[0085] The method comprises a step of twisting conductive wires 4 and forming at least one discontinuous longitudinal groove RI ([Fig. 10]) uncovering the conductive strand 40 of the conductive wires 4 at the periphery of the first conductor 1, each uncovered conductive strand 40 being a smoothing conductive strand 5.

[0086] In other words, a strand is formed with only conductive wires 4 that are identical, which is very practical. Then, a discontinuous longitudinal groove RI is formed so as to form smoothing conductive strands 5 comprising covered longitudinal portions PI with an insulating sheath 51 and uncovered longitudinal portions P2. The formation of a longitudinal groove RI makes it possible to remove the insulating sheath 41 from the conductive wires 4 locally and periodically at the periphery of the first conductor 1.

[0087] With reference to [Fig. 12], the discontinuous longitudinal groove RI comprises segments spaced apart by the contact pitch pc. Preferably, the contact pitch pc is equal to a multiple of the twist pitch pt.

[0088] By way of example, with reference to Figures 11 to 14, an abrasion device 900 is presented comprising three abrasion members 9 for simultaneously producing three discontinuous longitudinal grooves RL. It goes without saying that the number of abrasion members 9 could be different as well as their positions. The abrasion members 9 are preferably offset relative to the axis of the longitudinal cable 10 so that the contact zones ZC of the smoothing conductors 5 belong to different planes so as to distribute the contact zones ZC longitudinally and allow effective electrical potential of the first semiconductor layer 2. In this example, the abrasion device 900 makes it possible to produce three discontinuous longitudinal grooves RI spaced angularly apart.

[0089] The abrasion members 9 are positioned around the first conductor 1. Each abrasion member 9 is configured to come into contact with a conductive wire 4 of the periphery in a plane transverse to the first conductor 1 in which the abrasion member 9 can move. Each abrasion member 9 is configured to remove the insulation sheath 41 from the conductive wire 4 with which it comes into contact as illustrated in [Fig. 13]. With reference to [Fig. 15], after abrasion, the conductive strand 40 is devoid of insulation sheath 41 at the periphery of the first conductor 1 in order to form an uncovered portion P2, that is to say, a contact zone ZC.

[0090] In this embodiment, each abrasion member 9 comprises a frame 90 radially movable relative to the X axis of the first conductor 1 and an abrasive roller 91 driven in rotation relative to the chassis 90. It goes without saying that each abrasion member 9 could be in a different form.

[0091] The abrasion device 900 comprises a drive member 903 for the strand of conductive wires 4, that is to say the first conductor 1, with a drive pitch which corresponds to the contact pitch pc. Thus, each abrasion member 9 can form a contact zone ZC with a contact pitch pc which is very regular, preferably a multiple of the twisting pitch pt. ​​The drive member 903, for example a motorized winder, makes it possible to shift the longitudinal portions of the first conductor 1 in contact with the abrasion members 9.

[0092] Once the first conductor 1 has been obtained by one of the methods presented previously, the method comprises a step consisting of surrounding the first conductor 1 with a first semiconductor layer 2 so that the smoothing conductive strand 5 is in contact with the first semiconductor layer 2 along at least one contact zone ZC as illustrated in figures 16 and 17. The smoothing conductive strand 5 thus has the same electrical potential as the first semiconductor layer 2.

[0093] The method comprises a step of surrounding the first semiconductor layer 2 with an insulation layer 3. Preferably, this is carried out simultaneously by coextrusion.

[0094] This advantageously provides a “simple” longitudinal cable 10 allowing the transport of electrical power which makes it possible to avoid any risk of heating by “skin effect” and proximity effect while allowing smoothing of the electric field in order to increase electrical safety. The manufacture of the longitudinal cable 10 is practical given that it is sufficient to form the exposed portions P2 on a strand of conductive wires 4 which can be obtained in a practical manner.

[0095] With reference to figures 18 and 19, it is also possible to obtain a longitudinal cable 10 of the “coaxial” type which comprises a second layer of semiconductor 6 surrounding the insulation layer 3, a second conductor 7 surrounding the second layer of semiconductor 6 and an insulating protective sheath 8 surrounding the second conductor 7. The second conductor 7 can be of different natures such as a braid made up of cylindrical or flat strands, a covering made up of cylindrical or flat strands, a strip, or an assembly of these different technologies. According to one aspect, the second conductor 7 is sized to ensure the electromagnetic and lightning protection functions.The material of the insulating protective sheath 8 may be the same as that of the insulating layer 3 or another material among polymers of the PFA (perfluoroalkoxy), FEP (fluorinated ethylene propylene), ETFE (ethylene tetrafluoroethylene) type, silicones, fluorosilicones, ca. The outer insulating protective sheath 8 may also be made of materials used primarily for mechanical protection in the form of a braid, such as Kevlar (trade name), Nomex (trade name), glass fibers, aramid fibers, polyamide, or any other material suitable for the application.

[0096] It may in particular comprise a plurality of conductive wires 70 in contact with the second semiconductor layer 6 which is connected at the end to a reference potential so that the second semiconductor layer 6 is itself at this potential.

[0097] Thanks to the invention, any additional heating by "skin effect" and proximity effect is eliminated thanks to equipotentiality between the conductor and the semiconductor layer, making it possible to increase the performance of the electrical insulation by reducing the phenomena of partial discharges, the phenomena of local reinforcement of the electric field, the phenomena of space charges and the electrical aging of the insulation layer.

Claims

Claims

1. Longitudinal cable (10) for transporting electrical power, the longitudinal cable (10) comprising: • A first conductor (1), • A first semiconductor layer (2) surrounding the first conductor (1), • A first insulation layer (3) surrounding the first semiconductor layer (2), • the first conductor (1) having a periphery in contact with the first semiconductor layer (2), the first conductor (1) comprising: • a plurality of conductive wires (4) each comprising a conductive strand (40) which is covered with an insulating sheath (41) so that the conductive strands (40) are electrically insulated from each other, • the first conductor (1) comprising at least one discontinuous longitudinal groove (RI) at the periphery uncovering the conductive strand (40) of the conductive wires (4) at a contact zone (ZC),each exposed conductive strand (40) being a smoothing conductive strand (5), each smoothing conductive strand (5) comprising longitudinal portions (PI) covered with an insulating sheath (51) and exposed longitudinal portions (P2), the exposed longitudinal portions (P2) being in contact with the first semiconductor layer (2) at the contact zone (ZC) so that the first semiconductor layer (2) has the same electrical potential as the smoothing conductive strand (5), the contact zones (ZC) being spaced apart by the same contact pitch (pc).,

2. A longitudinal cable (10) according to claim 1, wherein the first conductor (1) comprises at least one strand (T4) of conductive wires (4) twisted with a twist pitch (pt) which is constant, the contact pitch (pc) is a multiple of the twist pitch (pt).

3. Longitudinal cable (10) according to claim 2, wherein the contact pitch (pc) is equal to the twist pitch (pt).

4. Longitudinal cable (10) according to one of claims 1 to 3, wherein the first conductor (1) comprises at least two discontinuous longitudinal grooves (RI), preferably at least three longitudinal grooves (RI).

5. Longitudinal cable (10) according to claim 4, wherein the discontinuous longitudinal grooves (RI) are angularly distributed at the periphery of the first conductor (1).

6. Longitudinal cable (10) according to one of claims 1 to 5, in which the uncovered portions (P2) are obtained by abrasion of the insulating sheath (41) of the conductive strand (40) of the conductive wire (4).

7. Longitudinal cable (10) according to one of claims 1 to 6, comprising: • A second semiconductor layer (6) surrounding the first insulation layer (3) and • A second conductor (7) surrounding the second semiconductor layer (6).

8. Propulsion chain for aircraft comprising a plurality of electrical equipment (El, E2, E3) connected by at least one power cable according to one of claims 1 to 7.

9. A method of manufacturing a longitudinal cable (10) for transporting electrical power, the method comprising steps of: • Providing a first conductor (1) comprising a plurality of conductive wires (4) each comprising a conductive strand (40) which is covered with an insulating sheath (41) so that the conductive strands (40) are electrically insulated from each other • Forming at least one discontinuous longitudinal groove (RI) at the periphery uncovering the conductive strand (40) of the conductive wires (4) at a contact zone (ZC), each uncovered conductive strand (40) being a smoothing conductive strand (5), each smoothing conductive strand (5) comprising longitudinal portions (PI) covered with a sheath insulation (51) and uncovered longitudinal portions (P2), • Surround the first conductor (1) with a first layer of semiconductor (2) so that the uncovered longitudinal portions (P2) are in contact with the first layer of semiconductor (2) at the contact zone (ZC) so that the first layer of semiconductor (2) has the same electrical potential as the smoothing conductive strand (5), the contact zones (ZC) being spaced apart by the same contact pitch (pc), • Surround the first layer of semiconductor (2) with a first layer of insulation (3).

10. Manufacturing method according to claim 9 comprising a step of twisting conductive wires (4) to obtain the first conductor (1) and a step of forming at least one discontinuous longitudinal groove (RI) uncovering the at least one conductive strand (40) of the conductive wires (4) at the periphery of the first conductor (1), each uncovered conductive strand (40) being a smoothing conductive strand (5).

11. Manufacturing method according to claim 10, wherein the at least one discontinuous longitudinal groove (RI) is produced by abrasion of the insulation sheath (41) of the conductive wires (4).

Images