FR2968138A1 - ELECTRICAL CONNECTION ASSEMBLY FORMED BY HIGH VOLTAGE ELECTRIC CABLE AND CONNECTING DEVICE - Google Patents

Abstract

The invention relates to an electrical connection assembly formed by an electric cable (4) and a connection device (5) fixed on a stripped end section (31 of the cable (4), which comprises a conductive core (26), a layer at least partially conducting conductor (28) covering said core (26) except on said terminal section (31) and an at least partially insulating layer (29) covering said conductive layer (28), said device (5) comprising a terminal (11) formed by an electrical connection portion (13) to an element with which it is configured to cooperate, a first longitudinally extending tubular portion (14) adapted to at least partially receive said terminal section (31) and a stepped tube (12). ) having an inclined transverse shoulder (23) whose angle of inclination with respect to said longitudinal direction is in the range [75 °, 95 °], and said insulating layer (29) is at least partially in contact with tact with said shoulder (23).

Description

The invention relates to the general field of electrical connection, and in particular to electrical connection assemblies formed by a high-voltage electrical cable and a connection device to be fixed on a bare terminal section of the electric cable. Already known such a set of electrical connection formed by a high-voltage electrical cable and a connection device to be fixed on a bare end section of the electric cable. This electric cable conventionally comprises a conductive core, a semiconductor layer covering the conductive core except on the stripped end portion and an insulating layer covering the semiconductor layer. The connection device is formed by a lug having a flat portion of electrical connection to an element with which said lug is configured to cooperate, and having a longitudinally extending tubular portion adapted to receive, in its hollow, the stripped terminal section of the electric cable. When the electric cable is powered, that is to say when a current flows in this cable, an electric discharge appears on the conductive core of the stripped end portion of the electric cable between a cut edge of the semiconductor layer and a free edge of the tubular portion of the pod. This electric discharge is caused by a difference in electric potential in the space between the cut edge of the semiconductor layer and the free edge of the terminal (also conductive). This phenomenon of electric discharge is accentuated in the case of high voltage electrical cable, called for example HTA, in which a current of 1 kV to 50 kV, and in particular of 6.6 kV to 15 kV, can be circulated, since the electric field near the pod is irregular.

This phenomenon is further accentuated in the case of electric cables of small radius of curvature (for example multi-strand cables) because in the vicinity of a conductive part of small radius of curvature, the electric field lines are sometimes concentrated in large proportions. This phenomenon is also called peak effect. The invention aims to improve this type of electrical connection assembly to use.

It proposes for this purpose a set of electrical connection formed by a high-voltage electrical cable and a connection device fixed on a bare terminal section of the electric cable, said electric cable comprising a conductive core, an at least partially conductive layer covering said conductive core except on said stripped end portion and an at least partially insulating layer covering said at least partially conductive layer, said connection device comprising a terminal formed by an electrical connection portion to an element with which said connection device is configured to cooperate and a first longitudinally extending tubular portion adapted to at least partially receive, in its hollow, said stripped end section of the electric cable, characterized in that said connection device further comprises a stepped tube having an inclined transverse shoulder of which angle of inclination with respect to said longitudinal direction is in the range [75 °; 95 °], and said at least partially insulating layer is at least partially in contact with said shoulder. Within the meaning of the invention, the contact between a cut edge of the at least partially insulating layer and the shoulder may not be a close contact. It is important that during the insertion of the cable into the connection device, the at least partially insulating layer and / or the at least partially conductive layer abut against the shoulder. Then, it is possible that the at least partially insulating layer and / or the at least partially conductive layer deviate very slightly from the shoulder due to the manipulation of the assembly before and after the assembly of the device and the cable. . This gap is electrically negligible and it is considered that there is contact, at least electrical, as long as the smallest distance separating the at least partially conductive layer and an inner surface of the stepped tube is less than or equal to about 2 mm. . Indeed, this distance is small enough that the air between the at least partially conductive layer and the stepped tube can not be electrically charged until an electric discharge appears. The fact that the connecting device comprises a stepped tube having an inclined transverse shoulder forming a stop during insertion of the cable thus allows the at least partially conductive layer to remain in close proximity (less than about 2 mm) of the inner surface. of the stepped tube. Thus, an equipotential bonding, or almost, is formed at this point of the cable and the electrical discharges are suppressed, or in any case significantly reduced. The electric arcs formed by these discharges are reduced or canceled. The shoulder is for example at right angles to the insertion direction of the electric cable in the connection device. In other words, this shoulder is different from a slightly inclined portion, often called a chamfer, helping the insertion of the electric cable, and whose angle of inclination with respect to the longitudinal direction is generally within a range [20 ° ; 50 °]. According to preferred, simple, convenient and economical characteristics of the electrical connection assembly according to the invention: the conductive core of the electric cable is formed by a plurality of strands; the stepped tube has a second longitudinally extending tubular portion intended to cover a non-stripped section of said electric cable; the second tubular portion of said stepped tube is in the extension of said shoulder; the second tubular portion of said stepped tube has an outside diameter greater than the outside diameter of said first tubular portion; the stepped tube has a first transition portion forming a first chamfer for inserting the core of said electric cable into said hollow of said first tubular portion; the first transition portion is in the extension of said shoulder; and the lug has a second transition portion connecting said electrical connection portion to said first tubular portion, which second transition portion is provided with an orifice opening into said hollow of said first tubular portion. According to a preferred characteristic, simple, convenient and economical of the assembly according to the invention, the stepped tube and said lug are in one piece.

According to another preferred, simple, convenient and economical feature of the assembly according to the invention, the stepped tube and said lug are distinct. Where appropriate, the stepped tube has a third tubular portion configured to be disposed at least partially within the first tubular portion of said lug. Preferably, the third tubular portion has an inner diameter approximately equal to the section of said conductive core of said electric cable, which makes it possible to reduce the internal space of the first tubular portion of the terminal and thus to tighten the conductive core more. electric cable. In the case of a multi-strand cable, this reduces the gaps between the strands. According to preferred, simple, convenient and economical characteristics of the assembly according to the invention: the third tubular portion has a reduced thickness with respect to the thickness of said first tubular portion; the second tubular portion is connected to said third tubular portion by said first transition portion; and - the first tubular portion of said lug has a second chamfer at a free end, second chamfer against which is disposed said first transition portion of said stepped tube.

We will now continue the disclosure of the invention by the description of embodiments, given below by way of illustration and not limitation, with reference to the accompanying drawings in which: - Figure 1 is a schematic plan view of an electric generator, here for a wind turbine connected to an electrical network via a connection assembly according to the invention; FIG. 2 is a sectional view of the link assembly partially showing an electric cable inserted into an electrical connection device according to a first embodiment; Figure 2A is a view of an enlarged detail of Figure 2; FIG. 3 is an isolated perspective view of the electrical connection device; - Figure 4 is a perspective-sectional view along the median plane of the connection device of Figure 3; FIG. 5 is an exploded perspective view of this connection device; and - Figure 6 is a view similar to Figure 2 according to a second embodiment. FIG. 1 very schematically illustrates a wind turbine 1 having a turbine provided with an electric generator 2 electrically connected to an interface of an electrical distribution network 3. The generator 2 and this interface 3 are electrically connected by an electrical connection assembly formed by a flexible electric cable 4 type HTA, that is to say multi-strand, and two connection devices 5 and 6 attached to each end of the cable 4. The electric generator 2 has a connection terminal 7 on which is mounted a lug 11 of the connection device 5 illustrated very schematically in Figure 1. The interface 3 of the electrical distribution network has a connection terminal 8 on which is mounted a lug 10 of the connection device 6 also illustrated so very schematic in Figure 1. In wind-powered electrical installations, it is generally necessary to use a cable HTA electric flexible because this cable follows a winding path to electrically connect two elements, here the generator 2 and the interface 3. In other words, the electric cable 4 must be flexible because it is bent in several areas so as to sneak between conventional electrical and mechanical equipment (not shown) of the wind turbine which are in a relatively small space. Electrical currents of at least 6.6 kV can flow in this cable 4 when it is powered. The connection device 5 mounted on the terminal 7 that is seen on the left in FIG. 1 and the electric cable 4 will now be described in greater detail in support of FIGS. 2 to 5. The connection device 6 mounted on the terminal 8 that is seen to the right in Figure 1 is identical to the connection device 5 described below. The connection device illustrated in Figures 2 to 5 comprises a copper lug 11 and a stepped tube 12 copper which are distinct. Lug 11 and tube 12 are both conductive. The pod 11 comprises a flat portion 13 connected to a tubular portion 14 (also called the first tubular portion) by a transition portion 15 (also called the second transition portion). The flat portion 13 is a contact area of generally parallelepiped shape. It has an orifice 16 adapted to receive a threaded rod (not shown) belonging to the electrical connection terminal 7 (Figure 1) for example provided with a support flange. To ensure the electrical contact between the terminal 7 and the lug 11, the flat portion 13 is clamped between the support flange and a nut screwed onto the threaded rod. The tubular portion 14 extends longitudinally and has a constant outside diameter throughout its length.

The tubular portion 14 further has a chamfer 17 (also called second chamfer) at a free end 18. This chamfer 17 extends from the inside of this tubular portion 14 to an edge 19 of this tubular portion 14 at its end. free end 18. This chamfer 17 has an angle of inclination relative to the longitudinal direction of about 45 °.

The transition portion 15 has an opening 20 opening inside the hollow of the tubular portion 14. This window 20 is formed by a cutting of material 21 made in the transition portion 15. This cutout 21 is folded in the hollow of the tubular portion 14. The lug 11 has a thickness in a range [1 mm; 5 mm].

The stepped tube 12 comprises a tubular portion 22 (also called the third tubular portion) connected to a shoulder 23 by a transition portion 24 (also called the first transition portion). This stepped tube 12 further comprises another tubular portion 25 (also called second tubular portion) extending in the extension of the shoulder 23. The tubular portions 22 and 25 each extend longitudinally and each have a constant outer diameter on all its length. The tubular portion 22 is adapted to be inserted into the hollow of the tubular portion 14 of the lug 11, with the outer surface of the tubular portion 22 which is adapted to be applied against the inner surface of the tubular portion 14 of the lug 11 For this, the outside diameter of the tubular portion 22 of the stepped tube 12 is smaller than the outside diameter of the tubular portion 14 of the lug 11 and less but almost equal to the inside diameter of the same tubular portion 14 so that the stepped tube 12 is adapted to be force-fitted into the hollow of the tubular portion 1. The transition portion 24 forms a chamfer (also called first chamfer) whose angle of inclination with respect to the longitudinal direction is approximately equal to 45 ° . This transition portion 24 is adapted to bear against the bevel 17 once the stepped tube 12 mounted with the lug 11. The shoulder 23 extends between the transition portion 24 and the tubular portion 25 transversely relative to the longitudinal direction. The angle of inclination of this shoulder 23 with respect to the longitudinal direction is here about 90 °.

The tubular portion 25, like the shoulder 23, extends outside the lug 11.

The stepped tube 12 has a thickness in a range [0.2 mm; 0.6 mm]. The electric cable 4 comprises a core 26 formed by several strands (not shown) themselves formed by a plurality of strands 27 which allows the cable 4 to be particularly flexible. This electric cable 4 further comprises a semiconductor layer 28 covering the conductive core 26, an insulating layer 29 silicone type covering the semiconductor layer 28, and an outer layer 30 formed by a polyester tape covering the insulating layer 29 and by a protective braid in synthetic and varnished fabric covering this polyester tape. The electric cable 4 here has a bare end portion 31, in other words with the semiconductor layer 28, the insulating layer 29 and the outer layer 30 which have been removed to reveal only the conductive core 26. The semiconductor layer conductor 28 has a thickness in the range [0.1 mm; 0.5 mm] and the insulating layer 29 is thicker than the semiconductor layer 28. This cable 4 has a non-stripped intermediate section 32 in the extension of the stripped end portion 31 and in the hollow of the tubular portion 25. junction between the sections 31 and 32 is at a cut edge 33 of the semiconductor layer 28, a cut edge 35 of the insulating layer 29 and a cut edge 37 of the outer layer 30. In the extension of this intermediate section 32 is a main section 36 of the cable 4 which is outside the stepped tube 12. The stripped end section 31 of the cable 4 is adapted to be inserted into the hollow of the tubular portion of the lug 11 to the electrical connection of the connection device 5 with this cable 4. In the case of a multi-strand electric cable 27, gaps are present between the strands 27, so that for a predetermined section of the conductive core 26 of this cable 4, it is sometimes necessary to use a lug 11 whose inner diameter of the tubular portion 14 is greater than the section of the conductive core 26 of this cable 4. Generally, for an electric cable having a solid conductive core, that is to say with a single strand, a lug having a tubular portion with an inner diameter substantially equal to the section of the conductive core must be used. For a multi-strand cable having the same section as the single-strand cable, it is sometimes necessary, depending on the section, to use a terminal having a tubular portion with an inside diameter that is greater. We will now describe in greater detail, again in support of Figures 2 to 5, the assembly of the electrical connection assembly formed by the cable 4, the lug 11 and the stepped tube 12. The tubular portion 22 of the tube step 12 is inserted by force into the hollow of the tubular portion 14 of the lug 11 until the transition portion 24 of the tube 12 bears against the transition portion 15 of the lug 11. In this position, the outer surface of the shoulder 23 is in abutment against the outer edge 19 of the lug 11. The connection device is thus assembled, which device was previously or not mounted on the connection terminal 7 via the lug 11. The cable 4 is then partially inserted in the connection device 5.

In particular, the stripped end section 31 of the cable 4 is received in the hollow of the tubular portion 14 of the lug 11, and at the same time in the hollow of the tubular portion 22 of the tube 12. The conductive core 26 has a which is approximately equal to the inside diameter of the tubular portion 22 of the stepped tube 12.

The insertion of all the strands 27, and in particular strands 27 located at the periphery of the conductive core 26 is facilitated by the transition portion 24 of the tube 12 which forms the first chamfer so that the strands 27 which are at the periphery of the core 26 are slid against this chamfer 24 until they enter the hollow of the tubular portion 22 of the tube 12.

The intermediate portion 32 is inserted into the connecting device until the cut edge 33 of the semiconductor layer 28, the cut edge 35 of the insulating layer 29 and the cut edge 37 of the outer layer 30 abut on the inner surface of the shoulder 23 of the stepped tube 12, and more particularly at a distance less than or equal to 2 mm (visible in Figure 2A). The window 20 formed in the transition portion 15 of the lug 11 makes it possible to verify that the cable 4 is sufficiently pushed inside the lug 11. The outer layer 30 is applied against the inner surface of the tubular portion 25. A crimping is then performed on the contour of the tubular portion 14 of the lug 11 so as to crimp the lug 11, the stepped tube 12 via its tubular portion 22 and the electric cable 4 via its bare end portion 31. The crimping is for example made with borrows of hexagonal shapes so as to further reduce the spaces between the strands 27 of the cable 4 at its bare end section 31.

Thanks to this crimping, the electrical connection assembly is formed with the cut edge 33 of the semiconductor layer 28 which comes in close proximity to the inner surface of the stepped tube 12, which makes it possible to cancel, or in any case to The electric disturbances generated by the peak effect at which the multi-strand electrical cable 27 is particularly subjected (due to the curvatures along this cable) are eliminated considerably at the level of the bare terminal section. In addition, even if the cable 4, and in particular the bare terminal section 31 and the intermediate section 32, deviates from the shoulder 23, for example because of the elongation (natural and / or or forced) of this cable 4, as illustrated in Figure 2, the respective cut edges 33, 35 and 37 remain at a very small distance from the stepped tube 12. In fact, the cut edges 35 and 37 only a small distance from the inner surface of the shoulder 23 and the cut edge 33 is at a maximum distance D less than or equal to about 2 mm from the inner surface of the chamfer 24. FIG. embodiment of the connection device.

In general, the same references have been used for the similar elements, but the number 100 has been added. Unlike the connection device 5 illustrated in FIGS. 2 to 5, the connection device 105 illustrated in FIG. lug 111, here in copper, and a stepped tube 112, here also made of copper, which lug 11 and tube 112 are made in one piece. Unlike the connection device 5, the connection device 105 has a tubular portion 125 of the same thickness as the tubular portion 114.

In addition, the second transition portion is merged with the first chamfer and the connection device 105 does not have a tubular portion 22 like that of the connection device 5. The insertion of the electric cable 104 into the connection device 105 is realized in a manner similar to the insertion of the electric cable 4 into the connecting device 5. The cut edge 135 of the insulating layer 129 abuts the inner surface of the shoulder 123 (and may move very slightly away from it then) and the cut edge 133 of the semiconductor layer 128 is at most at a distance less than or equal to about 2 mm from the inner surface of the chamfer. In non-illustrated variants: the stepped tube is made of a material other than copper, for example aluminum; the stepped tube has a thickness in a range [0.1 mm; 1 mm]; the shoulder of the stepped tube has an angle of inclination other than 90 ° with respect to the longitudinal direction, for example less than 90 ° or greater than 90 ° as long as this inclination angle is in the range [75 ° 95 °]; the tubular portion of the stepped tube is introduced by sliding rather than by force into the hollow of the tubular portion of the lug; the transition portion of the tube which facilitates insertion of the strands of the cable is curved along a radius; - The pod does not have a window; the electric cable has a solid conductive core, that is to say with a single strand, rather than multi-strand; the electric cable is suitable for carrying currents of more than 50 kV, it is then called HTB rather than HTA; the electric cable comprises a different structure, with more or fewer layers and / or with other materials; - The connection device further has a tubular heat shrink tubing mounted on the outer contour of the first tubular portion of the lug and extends at least to the main section of the electric cable; and the crimping is, for example, carried out by punching; The electrical connection assembly according to the invention is intended to equip more generally high voltage machines such as transformers, generators, motors, etc., in wind power or in other areas, for example in traction. It is recalled more generally that the invention is not limited to the examples described and shown.

Claims (15)

REVENDICATIONS1. Electrical connection assembly formed by a high voltage electrical cable (4; 104) and a connection device (5; 105) fixed on a stripped end section (31) of the electric cable (4; 104), said electric cable (4; 104) having a conductive core (26), an at least partially conductive layer (28; 128) covering said conductive core (26) except on said stripped end portion (31) and an at least partially insulating layer (29; 129) overlapping said at least partially conductive layer (28; 128), said connecting device (5; 105) having a lug (11; 111) formed by an electrical connection portion (13) to an element (2, 7) with which said connecting device (5; 105) is configured to cooperate and a first longitudinally extending tubular portion (14; 114) adapted to receive at least partially in its recess said bare terminal section (31) of the electric cable (4; 104), cara characterized in that said connecting device (5; 105) further comprises a stepped tube (12; 112) having an inclined transverse shoulder (23; 123) whose angle of inclination with respect to said longitudinal direction is in the range [75 °; 95 °], and said at least partially insulating layer (29; 129) is at least partially in contact with said shoulder (23; 123). 2. The assembly of claim 1, characterized in that the conductive core (26) of the electric cable (4; 104) is formed by a plurality of strands (27). 3. Assembly according to one of claims 1 and 2, characterized in that said stepped tube (12; 112) has a second tubular portion (25; 125) extending longitudinally provided to cover a non-stripped section (32) of said electric cable (4; 104). 4. The assembly of claim 3, characterized in that said second tubular portion (25; 125) of said stepped tube (12; 112) is in the extension of said shoulder (23; 123). 5. An assembly according to one of claims 3 and 4, characterized in that said second tubular portion (25; 125) of said stepped tube (12; 112) has an outer diameter greater than the outer diameter of said first tubular portion (14; 114). 6. An assembly according to any one of claims 1 to 5, characterized in that said stepped tube (12; 112) has a first transition portion (24) forming a first chamfer for insertion of the core (26). said electrical cable (4; 104) in said recess of said first tubular portion (14; 114). 7. The assembly of claim 6, characterized in that said first transition portion (24) is in the extension of said shoulder (23; 123). 8. The assembly as claimed in claim 1, wherein said lug (11; 114), which second transition portion (15) is provided with an orifice (20) opening into said hollow of said first tubular portion (14; 114). 9. An assembly according to any one of claims 1 to 8, characterized in that said stepped tube (112) and said lug (111) are in one piece. 10. An assembly according to any one of claims 1 to 8, characterized in that said stepped tube (12) and said lug (11) are distinct. 11. The assembly of claim 10, characterized in that said stepped tube (12) has a third tubular portion (22) configured to be disposed at least partially within the first tubular portion (14) of said lug (11). ). 12. The assembly of claim 11, characterized in that said third tubular portion (22) has an inner diameter approximately equal to the section of said conductive core (26) of said electric cable (4). 13. Assembly according to one of claims 11 and 12, characterized in that said third tubular portion (22) has a reduced thickness relative to the thickness of said first tubular portion (14). 14. An assembly according to any one of claims 11 to 13 and according to claim 6, characterized in that said second tubular portion (28) is connected to said third tubular portion (22) by said first transition portion (24). 15. The assembly of claim 14, characterized in that said first tubular portion (14) of said lug (11) has a second chamfer (17) at a free end (18), second chamfer (17) against which is disposed said first transition portion (24) of said stepped tube (12).