Medium voltage electrical device

Abstract

A medium-voltage electrical apparatus (100) is proposed, comprising: - a wall (20) configured to be at a first electrical potential (V1), - an electrical conductor (2) configured to be at a second electrical potential (V2) different from the first electrical potential (V1), - a tube (1) passing through the wall (20) and surrounding the electrical conductor (2), - a sleeve (3) made of insulating material, wherein the sleeve (3) surrounds the tube (1) and is in contact with an external surface (4) of the tube (1). Abstract figure: Figure 2

Description

Title of the invention: Medium voltage electrical apparatus technical field

[0001] The present invention relates to the field of medium voltage electrical equipment, that is to say, whose nominal operating voltage is between 1 kV and 52 kV.

[0002] These devices are part of a medium voltage type electrical distribution network. Previous technique

[0003] It is known to place certain electrical components, for example fuse wells or insulating bushings, in a pressurized enclosure containing an electrically insulating gas, such as sulfur hexafluoride. This gas, possessing excellent dielectric properties, ensures electrical insulation and prevents the formation of electrical arcs between the various electrical conductors present in the enclosure. However, this gas also has a high global warming potential, and it is therefore desirable not to use it. It is thus possible to use instead gases with a low global warming potential, such as air, nitrogen, or carbon dioxide. These gases have lower dielectric strength than the gas being replaced. The insulating power can be improved by increasing the pressure of the gas contained in the enclosure.However, a significant increase in pressure necessitates stiffening the enclosure structure to prevent excessive deformation. Furthermore, reducing the size of the installations is desirable, which requires bringing the electrical conductors closer together, thus increasing dielectric insulation requirements. A pressure increase alone may not be sufficient to achieve the expected performance.

[0004] There is therefore a need for medium voltage electrical equipment in which the dielectric insulation is improved, particularly at the level of fuse wells or insulating bushings. Summary

[0005] To this end, the invention proposes a medium-voltage electrical device, comprising: - a wall configured to be at a first electrical potential, - an electrical conductor configured to be at a second electrical potential different from the first electrical potential, - a tube made of insulating material, passing through the wall and surrounding the electrical conductor, - a sleeve made of insulating material, in which the sleeve surrounds the tube and is in contact with an external surface of the tube.

[0006] The sleeve reduces dielectric stresses on the tube surface near the wall. This improves the voltage resistance of the electrical device.

[0007] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination:

[0008] The wall may be part of an enclosure containing a part of the electrical conductor, a part of the tube and the sleeve.

[0009] The wall is metallic.

[0010] The first electrical potential is, for example, that of the mass (or earth).

[0011] The second electrical potential is, for example, the potential of one phase of a medium-voltage three-phase network. The second electrical potential thus corresponds to the high voltage of the network.

[0012] According to one embodiment, the electrical conductor passes through the wall.

[0013] The tube is cylindrical.

[0014] The tube is made of electrically insulating material.

[0015] The tube is for example made of epoxy resin or of thermoplastic engineering material.

[0016] The tube and the electrical conductor are coaxial.

[0017] The sleeve is cylindrical.

[0018] The enclosure can be sealed. The enclosure can contain a gas at a pressure greater than atmospheric pressure.

[0019] According to one aspect of the electrical device, the sleeve comprises: - a first portion in contact with the external surface of the tube, the first portion having a shape complementary to the external surface of the tube, - a second portion extending the first portion along an axial direction, the second portion being distant from the external surface of the tube.

[0020] The shape of the sleeve makes it possible to increase the path distance along the sleeve, and therefore to improve the dielectric insulation.

[0021] According to one embodiment, the first portion of the sleeve is cylindrical in shape.

[0022] The tube may have, in the area in contact with the sleeve, the shape of a cylinder of revolution. In this case, the first portion of the sleeve also has the shape of a cylinder of revolution.

[0023] A radially internal surface of the first portion is in contact with the external surface of the tube.

[0024] According to one embodiment, the entire radially internal surface of the first portion is in contact with the external surface of the tube.

[0025] According to one embodiment of the electrical device, the second portion is flared in shape, the second portion widening between a junction zone with the first portion and a free end of the second portion.

[0026] According to one embodiment, the second portion is flared in shape, the radial distance between the second portion and the external surface of the tube increasing as the axial distance between the second portion and the first portion increases.

[0027] According to a particular embodiment, the second portion of the sleeve is conical in shape.

[0028] A generatrix of the second portion of conical shape forms an angle between 15° and 70° with the axis of the cone.

[0029] The first cylindrical portion and the second conical portion can be coaxial.

[0030] According to one embodiment, the first portion of the sleeve extends axially over a length between 10% and 50% of a diameter of the first portion.

[0031] According to one embodiment, the second portion of the sleeve extends axially over a length between 10% and 30% of the diameter of the first portion.

[0032] According to one embodiment of the electrical device, the second portion of the sleeve is substantially cylindrical in shape, and an internal diameter of the second portion is greater than an external diameter of the tube.

[0033] According to one embodiment of the electrical device, the sleeve is in contact with the wall.

[0034] The cylindrical portion of the sleeve includes an axial surface, and the axial surface is in contact with the wall.

[0035] According to one embodiment, the sleeve is made of elastomeric material.

[0036] According to one aspect of the electrical device, the sleeve is constrained radially.

[0037] A radial extension rate of the sleeve is between 5% and 12%.

[0038] The external surface of the tube includes a portion for receiving the sleeve. The the receiving portion has a roughness of less than 0.8 micron.

[0039] The radially internal surface of the first portion of the sleeve has a roughness of less than 0.8 micron.

[0040] According to one embodiment of the electrical device, the first portion of the sleeve includes a groove opening into an axial surface of the first portion.

[0041] The axial surface of the cylindrical portion of the sleeve comprises a first radially internal portion and a second radially external portion. The first portion and the second portion of the axial surface are separated by the groove.

[0042] The throat is annular in shape.

[0043] The groove and the cylindrical portion of the sleeve can be coaxial.

[0044] The groove extends axially over a length between 5% and 15% of the diameter of the first portion of the sleeve.

[0045] In the free state of the sleeve, the groove extends radially over a distance of between 4% and 10% of the diameter of the first portion of the sleeve.

[0046] According to one embodiment, a bottom of the throat has a rounded shape.

[0047] A bottom of the throat has substantially the shape of a half-torus.

[0048] According to one embodiment, the throat comprises an electrically semi- driver.

[0049] For example, the throat is coated with an electrically semiconducting paint.

[0050] Electrically semiconducting paint is a paint loaded with semiconducting particles.

[0051] According to one embodiment of the electrical device, the throat is filled at least in part with an electrically semiconducting elastomer.

[0052] The electrically semiconducting elastomer is a silicone resin loaded with semiconducting particles.

[0053] The throat can be completely filled with an electrically semiconducting elastomer.

[0054] According to one embodiment of the electrical device, the first portion of the sleeve comprises a set of electrically conductive tabs extending towards the wall and in contact with the wall.

[0055] The tabs extend axially from the axial surface of the first portion of the sleeve.

[0056] The tabs ensure electrical contact between the semiconducting material of the groove and the wall, even when the axial surface of the sleeve is not perfectly pressed against the wall.

[0057] According to one embodiment, the electrical device comprises an electrically conductive rod extending from the wall to a bottom of the throat, the electrically conductive rod being in contact with the electrically semiconductive material of the throat.

[0058] The conductive rod ensures electrical contact between the wall and the semiconducting material of the groove, even when the axial surface of the sleeve is not perfectly pressed against the wall.

[0059] The electrically conductive rod can be a metal screw passing through the wall.

[0060] In the case of a fuse well, the electrical conductor includes a fuse.

[0061] A first terminal of the fuse is received in a first receptacle connected to a first portion of the rod of the electrical conductor. A second terminal of the fuse is received in a second receptacle connected to a second portion of the electrical conductor rod.

[0062] According to one embodiment, the electrical device is configured to circulate an electric current in a medium voltage electrical network comprising three phases. The electrical device comprises, respectively for each phase: - an electrical conductor disposed within the enclosure, - a tube passing through the wall and surrounding the electrical conductor, - a sleeve surrounding an external surface of the tube. Brief description of the drawings

[0063] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0064] [Fig.1] is a schematic representation of a medium voltage electrical device,

[0065] [Fig.2] is a perspective view of an electrical device according to a mode of realization of the invention,

[0066] [Fig.2] is a partial side and cross-sectional view of an electrical device according to a method of embodiment of the invention,

[0067] [Fig.3] is another partial, side and cross-sectional view of the electrical apparatus of the [Fig.2],

[0068] [Fig.4] is a partial, side and cross-sectional view of an alternative embodiment of the electrical device shown in figures 2 and 3,

[0069] [Fig.5] is a perspective view of an insulating sleeve of the electrical device of the Figures 2 and 3,

[0070] [Fig.6] is a perspective section of the insulating sleeve of [Fig.5],

[0071] [Fig.7] is a partial perspective section of an alternative embodiment of the apparatus electrical diagrams of figures 2 and 3. Description of the implementation methods

[0072] To facilitate reading the figures, the different elements are not necessarily shown to scale. In these figures, identical elements bear the same reference numerals. Certain elements or parameters may be indexed, that is, designated, for example, as first element or second element, or first parameter and second parameter, etc. This indexing aims to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another, and the designations may be interchanged. When it is specified that a device The presence of a given element does not exclude the presence of other elements in this device.

[0073] Figure 1 shows an electrical device 100 configured to circulate an electric current in a medium-voltage electrical network. The electrical network comprises three phases, designated by P1, Ph2, Ph3.

[0074] The electrical device 100 comprises, respectively for each of the phases Phi, Ph2, Ph3: - an electrical conductor 2,2',2" disposed in enclosure 30, - a tube 1,1',1" passing through wall 20 and surrounding respectively the electrical conductor 2,2',2', - a 3,3',3" sleeve surrounding an outer surface 4,4' of the 1,1',1" tube.

[0075] Thus, each of the phases Phi, Ph2, Ph3 of the electrical device 100 comprises respectively an electrical conductor 2, 2', 2" arranged in a tube 1,1',1" and passing through the wall 20. A sleeve 3,3',3" is respectively arranged on the corresponding tube 1,1',1".

[0076] As illustrated in particular in [Fig.2], the proposed medium-voltage electrical apparatus 100 comprises: - a wall 20 configured to be at a first electrical potential VI, - an electrical conductor 2 configured to be at a second electrical potential V2 different from the first electrical potential VI, - a tube 1 made of insulating material, passing through the wall 20 and surrounding the electrical conductor 2, - a sleeve 3 made of insulating material, in which the sleeve 3 surrounds the tube 1 and is in contact with an external surface 4 of the tube 1.

[0077] The sleeve 3 reduces the dielectric stresses on the surface of the tube 1 near the wall 20. The voltage resistance of the electrical device 100 is thus improved.

[0078] The wall 20 can be part of an enclosure 30 containing a part of the electrical conductor 2, a part of the tube 1 and the sleeve 3. Wall 20 is metallic.

[0079] The first electrical potential V1 is for example that of mass, which can also be designated by the term earth. The second electrical potential V2 is, for example, the potential of one phase of a medium-voltage three-phase network. The second electrical potential thus corresponds to the high voltage of the network. In [Fig. 2], the potential VI and the potential V2 are indicated by a dashed line.

[0080] The electrical conductor 2 passes through the wall 20.

[0081] Tube 1 is cylindrical. Tube 1 extends along an axis DI. Tube 1 is made of electrically insulating material. Tube 1, for example, is made of epoxy resin or engineering thermoplastic material.

[0082] Tube 1 and electrical conductor 2 are coaxial. An internal volume of tube 1 forms a receiving volume for electrical conductor 2.

[0083] The sleeve 3 is cylindrical. Sleeve 3 extends along an axis D3. Sleeve 3 and tube 1 are coaxial.

[0084] The enclosure 30 can be sealed. The enclosure 30 can contain a gas at a pressure greater than atmospheric pressure. The gas could be air. The gas could be a dielectric gas, such as sulfur hexafluoride.

[0085] In the illustrated example, tube 1 corresponds to a fuse well. Tube 1 contains a fuse 25, through which the electric current passes. Fuse 25 is designed to melt when the current exceeds a predefined threshold, thus interrupting the flow of current in case of overcurrent and protecting the electrical circuit.

[0086] Figure 2 details the arrangement of the electrical device 100 in the case where the tube 1 is a fuse well. In this application example, the electrical conductor 2 includes the fuse 25. In other words, the fuse 25 is part of the conductor 2 arranged in the tube 1. Tube 1 includes at a first axial end a first connector 22A which is electrically connected to a first receptacle 24A receiving a first connection terminal of fuse 25. A first portion of the rod of the electrical conductor 2 is connected at the first connector 22A. The first terminal of fuse 25 is thus received in the first receptacle 24A connected to a first portion of the rod of the electrical conductor 2. Tube 1 includes a second connector 22B electrically connected to a second receptacle 24B, which receives a second terminal for the fuse 25. A second section of the electrical conductor 2 is connected to the second connector 22B. The second terminal of the fuse 25 is thus received in a second receptacle 24B connected to a second section of the electrical conductor 2. The first receptacle 24A and the second receptacle 24B are electrically conductive and are, for example, made of metal. The first receptacle 24A and the second receptacle 24B are at a distance from each other. The electric current can pass from the first receptacle 24A to the second receptacle 24B only by passing through fuse 25. The first receptacle 24A and the second receptacle 24B are thus part of the conductor 2 arranged in the tube 1. The symbols il schematically illustrate the passage of electric current, from an input connector 21 to the portion of the electrical conductor 2 connected to the second connector 22B. A cover 13, when closed, seals the axial end of the fuse holder. The cover 13 can be opened to access the fuse 25, for example, for installation or replacement as needed. In the closed position, the cover 13 presses against an electrical insulator 14, which in turn presses against the second receptacle 24B.

[0087] In [Fig.2], the symbols 22A' and 22B' designate the first and second connectors of the tube 1' corresponding to the second phase of the electrical device 100. The sleeve surrounding the tube 1' is designated by the symbol 3'. The sleeve 3' is in contact with an external surface 4' of the tube 1'. The tube corresponding to the third phase was not shown. The three tubes are arranged in the electrical device 100 in such a way as to minimize the overall size, while minimizing dielectric stresses.

[0088] According to the illustrated example, corresponding to a fuse well, the electrical conductor 2 is distant from an internal surface 5 of the tube 1.

[0089] According to another embodiment, not shown, the electrical conductor 2 is in contact with an internal surface 5 of the tube 1. This case could correspond, for example, to an insulating penetration. Tube 1 can be overmolded onto an outer lateral surface of electrical conductor 2. In the case of a through-hole, the electrical conductor 2 passes through the tube 1 from a first axial end of the tube 1 to the second axial end of the tube 1.

[0090] The electrical conductor 2 comprises a rigid copper rod. The rigid rod is solid.

[0091] As detailed in particular in Figures 3 and 4, sleeve 3 comprises: - a first portion 7 in contact with the external surface 4 of the tube 1, the first portion 7 having a shape complementary to the external surface 4 of the tube 1, - a second portion 8 extending the first portion 7 in an axial direction, the second portion 8 being distant from the external surface 4 of the tube 1.

[0092] The shape of the sleeve makes it possible to increase the path distance along the sleeve 4, and thus to reduce dielectric stresses.

[0093] The first portion 7 of the sleeve 3 is here cylindrical in shape.

[0094] In the illustrated example, the tube 1 has, in the area in contact with the sleeve 3, the shape of a cylinder of revolution. The first portion 7 of the sleeve 3 also has the shape of a cylinder of revolution.

[0095] The first portion 7 of the sleeve 3 can thus fit the external surface 4 of the tube 1. In other words, a radially internal surface 9 of the first portion 7 is in contact with the external surface 4 of the tube 1. According to the illustrated example, the entire radially internal surface 9 of the first portion 7 is in contact with the external surface 4 of the tube 1. The symbol 6 designates the area of ​​the outer surface 4 of the tube 1 which is in contact with the first portion 7 of the sleeve 3.

[0096] According to the embodiment of the electrical device 100 illustrated in particular in Figures 2 and 3, the second portion 8 is flared in shape. The second portion 8 widens between a junction zone with the first portion 7 and a free end of the second portion 8.

[0097] The second portion 8 is flared in shape, and a radial distance between the second portion 8 and the external surface 4 of the tube 1 increases when the axial distance between the second portion 8 and the first portion 7 increases.

[0098] A radially internal surface 10 of the second portion 8 is opposite the external surface 4 of the tube 1 along a radial direction R. Surface 10 comprises a first portion 10-1 extending from surface 9, and a second portion 10-2 extending from the first portion 10-1.

[0099] According to the embodiment illustrated in particular in figures 2 and 3, the second portion 8 of the sleeve 3 is conical in shape. A generator G of the second portion 8 of conical shape forms an angle α between 15° and 70° with the axis D8 of the cone.

[0100] The first portion 7, which is cylindrical in shape, and the second portion 8, which is conical in shape, are coaxial. The axis of the first portion 7 is designated by D7 and the axis of the second portion 8 is designated by D8. According to the illustrated example, in particular on [Fig.5], these two axes are coincident, and coincide with the axis D3 of the sleeve 3.

[0101] As shown in Figures 6 and 7, the first portion 7 of the sleeve 3 extends axially along a length L1 between 10% and 50% of a diameter di7 of the first portion 7. The second portion 8 of the sleeve 3 extends axially along a length L2 between 10% and 30% of the diameter di7 of the first portion 7. Lengths L1 and L2 are measured along axis D3 of sleeve 3.

[0102] Figure 4 illustrates an embodiment of the electrical apparatus 100 in which the second portion 8 of sleeve 3 is not conical. According to this embodiment, the second portion 8 of the sleeve 3 is substantially cylindrical in shape, and an internal diameter of the second portion 8 is greater than an external diameter of the tube 1. By substantially cylindrical we mean that a slight angle is possible, corresponding to a draft angle allowing good demolding of the sleeve 3 when it is molded.

[0103] According to the embodiments illustrated in figures 2 to 4, the sleeve 3 is in contact with the wall 20.

[0104] The sleeve 3 covers the area forming the interface between the tube 1 and the wall 20. The shape of the sleeve 3 allows it to act as a deflector for the electric field lines, and allows to reduce the dielectric stresses.

[0105] The cylindrical portion 7 of the sleeve 3 comprises an axial surface 11, and the axial surface 11 is in contact with the wall 20.

[0106] The sleeve 3 is made of elastomeric material. Sleeve 3, for example, is formed by injection.

[0107] The sleeve 3 is constrained radially. The radial extension rate of sleeve 3 is between 5% and 12%. This radial extension rate is chosen according to the elasticity of the elastomer.

[0108] The radial extension rate of sleeve 3 is defined by: the difference between the outside diameter del of tube 1 and the inside diameter di7 of the first portion 7 of sleeve 3, when sleeve 3 is in the free state, divided by the outside diameter del of tube 1. The free state is defined as a state in which the sleeve 3 is not mounted on the tube 1 and is not deformed. The state before mounting is therefore a free state, without deformation of the sleeve 3.

[0109] The external surface 4 of the tube 1 includes a receiving portion 6 of the sleeve 3. This receiving portion is the portion of the external surface 4 with which the radially internal surface 9 of the sleeve 3 is in contact. The receiving portion 6 has a roughness Ra of less than 0.8 micron. The Ra roughness is measured in accordance with ISO 10110-8. The radially internal surface 9 of the first portion 7 of the sleeve 3 also has a roughness Ra of less than 0.8 micron.

[0110] The sleeve 3 is thus sufficiently constrained, and the contact surfaces 6, 9 are sufficiently smooth so that the interface between the sleeve 3 and the tube 1 is free of air gaps. In other words, the low roughness of the contact surfaces 6, 9, as well as the stress experienced by the sleeve 3 when it is placed on the tube 1, mean that Air molecules are expelled from the interface between the contacting parts when sleeve 3 is put in place around tube 1.

[0111] According to the illustrated example, the first portion 7 of the sleeve 3 includes a groove 15 opening into an axial surface 11 of the first portion 7.

[0112] As can be seen particularly on [Fig.6], the axial surface 11 of the cylindrical portion 7 of the sleeve 3 comprises a first radially internal portion 11-1 and a second radially external portion 11-2. The first portion 11-1 and the second portion 11-2 of the axial surface 11 are separated by the groove 15.

[0113] The groove 15 is annular in shape. The groove 15 and the cylindrical portion 7 of the sleeve 3 are coaxial here.

[0114] The first portion 11-1 of the axial surface has a constant width. This width is measured along a radial direction. The second portion 11-2 of the axial surface also has a constant width. The width is measured along a radial direction. The width of the first portion 11-1 can be equal to the width of the second portion 11-2.

[0115] The groove 15 extends axially along a length L3, schematically shown on [Fig.7], between 5% and 15% of the diameter di7 of the first portion 7 of the sleeve 3.

[0116] In the free state of the sleeve 3, the groove 15 extends radially over a distance L4 between 4% and 10% of the diameter di7 of the first portion 7 of the sleeve 3.

[0117] The groove 15 has a bottom 16. The bottom 16 of the groove 15 has a rounded shape. A bottom 16 of the groove 15 is substantially in the shape of a half-torus. The axis of the semi-torus coincides with the axis of the second portion 8 of the sleeve 3.

[0118] According to one embodiment, illustrated in Figures 5 and 6, the groove 15 comprises an electrically semiconducting material.

[0119] For example, the groove 15 is coated with an electrically semiconducting paint. Electrically semiconducting paint is a paint loaded with semiconducting particles. The entire surface of the groove 15, that is to say the portion between the first portion 11-1 of the axial surface 11 and the second portion 11-2 of the axial surface 11, is coated with an electrically semiconducting paint. The material in which the groove 15 is formed can receive a surface treatment promoting the adhesion of the semiconducting paint.

[0120] According to one embodiment of the electrical device 100, the groove 15 is filled at least in part with an electrically semiconducting elastomer. In this case, the electrically semiconducting elastomer can be a silicone resin loaded with semiconducting particles. The throat 15 can be completely filled with an electrically semiconducting elastomer.

[0121] The radially internal surface 9 of the first portion 7 of the sleeve 3 is devoid of semiconductor material. In other words, the semiconductor material deposited on the walls of the groove is not deposited on the part of the sleeve in contact with the external surface 4 of the tube 1. Similarly, the external lateral surface of the first portion 7 is insulating and contains no semiconductor material. The same is true of the second portion 8. During the application of the semiconducting paint or semiconducting elastomer, the radially internal surface 9 and the external lateral surface can be temporarily masked with a protective film to prevent splashing or dripping of the applied compound. The protective film is then removed to obtain the finished part.

[0122] According to one embodiment of the electrical device 100, illustrated in [Fig.7], the first portion 7 of the sleeve 3 comprises a set of electrically conductive tabs 12 extending towards the wall 20 and in contact with the wall 20.

[0123] The tabs 12 extend axially from the axial surface 11 of the first portion 7 of the sleeve 3. The tabs 12 ensure electrical contact between the semiconducting material of the groove 15 and the wall 20, even when the axial surface 11 of the sleeve 3 is not perfectly pressed against the wall 20. Indeed, the tabs 12 have a length greater than the maximum value of axial play that can be present between the sleeve 3 and the wall 20.

[0124] According to embodiments of figures 3 and 4, the electrical device 100 comprises an electrically conductive rod 19 extending from the wall 20 to a bottom 16 of the groove 15, the electrically conductive rod 19 being in contact with the electrically semiconductive material of the groove 15.

[0125] The conductive rod 19 ensures electrical contact between the wall 20 and the semiconducting material of the groove 15, even when the axial surface 11 of the sleeve 3 is not perfectly pressed against the wall 20. The conducting rod 19 is visible in [Fig.3] and in [Fig.4]. The electrically conductive rod 19 can be a metal screw passing through the wall 20. The length and diameter of the screw are chosen to ensure contact with the wall of the groove 15.

Claims

Demands

1. Medium voltage electrical apparatus (100), comprising: - a wall (20) configured to be at a first electrical potential (VI), - an electrical conductor (2) configured to be at a second electrical potential (V2) different from the first electrical potential (VI), - a tube (1) passing through the wall (20) and surrounding the electrical conductor (2), - a sleeve (3) of insulating material, in which the sleeve (3) surrounds the tube (1) and is in contact with an external surface (4) of the tube (1).

2. Electrical device according to claim 1, wherein the sleeve (3) comprises: - a first portion (7) in contact with the external surface (4) of the tube (1), the first portion (7) having a shape complementary to the external surface (4) of the tube (1), - a second portion (8) extending the first portion (7) in an axial direction, the second portion (8) being distant from the external surface (4) of the tube (1).

3. Electrical device according to claim 2, wherein the second portion (8) is flared in shape, the second portion (8) widening between a junction zone with the first portion (7) and a free end of the second portion (8).

4. Electrical device according to the preceding claim, wherein the second portion (8) of the sleeve (3) is conical in shape.

5. Electrical device according to any one of the preceding claims, wherein the sleeve (3) is in contact with the wall (20).

6. Electrical device according to any one of the preceding claims, wherein the sleeve (3) is made of elastomeric material.

7. Electrical device according to any one of the preceding claims, wherein the sleeve (3) is radially constrained.

8. Electrical apparatus according to any one of the preceding claims in combination with claim 2, wherein the first portion (7) of the sleeve (3) comprises a groove (15) opening into an axial surface (11) of the first portion (7), the throat (15) comprising an electrically semiconducting material.

9. Electrical device according to the preceding claim, in which the groove (15) is coated with an electrically semiconducting paint.

10. Electrical apparatus according to any one of claims 8 or 9, wherein the groove (15) is filled at least in part with an electrically semiconducting elastomer.

11. Electrical device according to any one of the preceding claims in combination with claim 2, wherein the first portion (7) of the sleeve (3) comprises a set of tabs (12) extending towards the wall (20) and in contact with the wall (20).

12. Electrical device according to the preceding claim, wherein the tabs (12) extend axially from the axial surface (11) of the first portion (7) of the sleeve (3).

13. Electrical apparatus according to any one of claims 8 to 10, comprising an electrically conductive rod (19) extending from the wall (20) to a bottom of the groove (15), the electrically conductive rod (19) being in contact with the electrically semiconductive material of the groove (15).

14. Electrical apparatus according to any one of the preceding claims, configured to circulate an electric current in a medium voltage electrical network comprising three phases (Phi, Ph2, Ph3), the electrical apparatus (20) comprising respectively for each of the phases: - an electrical conductor (2,2',2”) disposed in the enclosure (30), - a tube (1,1',1”) passing through the wall (20) and respectively surrounding the electrical conductor (2,2',2”), - a sleeve (3,3',3”) surrounding an external surface of the tube (1,1',1”).