Screen connectors for electrical cables and jointing assemblies comprising the screen connector

Abstract

A screen connector for electrical cables may include: a conductive shield sock extending about a longitudinal axis and configured to couple to a conductive screen of at least one electrical cable or to at least one jointing assembly for the electrical cables; a shrinkable protective sleeve arranged in a radially outer position with respect to the conductive shield sock; at least one first removable support element arranged in a radially inner position with respect to the conductive shield sock and configured to hold the conductive shield sock and the shrinkable protective sleeve in a radially expanded state; and/or at the axially opposite end portions of the screen connector, at least one watertight element. The at least one watertight element may be radially interposed between the conductive shield sock and the shrinkable protective sleeve.

Claims

1. A jointing assembly for electrical cables, the jointing assembly comprising: a shrinkable sleeve of dielectric material, extending about a longitudinal axis, the shrinkable sleeve of dielectric material configured to receive an electrical cable; a connector configured to connect an electrical cable to an electrical component, said connector being housed in a radially inner position in the shrinkable sleeve; at least one removable support element coaxially arranged with respect to the shrinkable sleeve in a radially inner position of the shrinkable sleeve and configured to hold the shrinkable sleeve in a radially expanded state; and at least one screen connector positioned at least at one end portion of the shrinkable sleeve, the at least one screen connector including, a conductive shield sock extending about the longitudinal axis and configured to couple to a conductive screen of one electrical cable; a shrinkable protective sleeve arranged in a radially outer position with respect to the conductive shield sock; at least one further removable support element arranged in a radially inner position with respect to the conductive shield sock and configured to hold the conductive shield sock and the shrinkable protective sleeve in a radially expanded state.

2. The jointing assembly of claim 1, wherein the at least one further removable support element includes a tubular element.

3. The jointing assembly of claim 2, wherein the tubular element is defined by a rigid body or a helically wound strip.

4. The jointing assembly of claim 1 further comprising: a metallic screen in a radially outer position with respect to the shrinkable sleeve.

5. The jointing assembly of claim 4 wherein the screen connector is arranged in a radially outer position with respect to the metallic screen.

6. The jointing assembly of claim 4 wherein the screen connector is arranged in a radially inner position with respect to the shrinkable sleeve.

7. The jointing assembly of claim 1 wherein the shrinkable sleeve includes a cylindrical insert made from a conductive or semi-conductive material.

8. The jointing assembly of claim 7 wherein the cylindrical insert is incorporated into the dielectric material of the shrinkable sleeve.

9. The jointing assembly of claim 1, further comprising: at the axially opposite end portions of the screen connector, at least one watertight element radially interposed between the at least one removable support element and the shrinkable protective sleeve.

10. The jointing assembly of claim 9, wherein the at least one watertight element is radially interposed between the at least one removable support element and the conductive shield sock.

11. The jointing assembly of claim 9, further comprising: at axially opposite end portions of the screen connector, at least one additional watertight element; wherein the at least one additional watertight element is radially interposed between the at least one further removable support element and the shrinkable protective sleeve.

12. The jointing assembly of claim 11, wherein the at least one watertight element and the at least one additional watertight element are arranged at a same axial position.

13. The jointing assembly of claim 11, wherein the at least one additional watertight element is radially interposed between the at least one first removable support element and the conductive shield sock.

14. The jointing assembly of claim 1, further comprising: at least one metallic braid coupled to the conductive shield sock and radially interposed between the conductive shield sock and the shrinkable protective sleeve.

15. The jointing assembly of claim 1, further comprising: a connection element associated with the conductive shield sock; wherein the connection element is a plug-in electrical connector, a lug, or a mechanical connector.

16. The jointing assembly of claim 1, wherein the at least one further removable support element includes a tubular element defined by a rigid body.

17. The jointing assembly of claim 1, wherein the at least one further removable support element includes a tubular element defined by a helically wound strip.

Description

(1) Further features and advantages of a screen connector and of a jointing assembly comprising a screen connector in accordance with the present invention will appear more clearly from the following detailed description of some preferred embodiments thereof, such description being provided merely by way of non-limiting examples and being made with reference to the annexed drawings. In such drawings:

(2) FIG. 1 is a schematic perspective view of a first embodiment of a screen connector according to the present invention;

(3) FIG. 2 is a schematic view of a longitudinal section of the screen connector of FIG. 1;

(4) FIG. 3 is a schematic exploded view of the screen connector of FIG. 1;

(5) FIG. 4 is a schematic partially sectioned view of a first embodiment of a jointing assembly according to the present invention, in a specific operative configuration;

(6) FIG. 5 is a schematic partially sectioned view of a second embodiment of a jointing assembly according to the present invention, in a specific operative configuration;

(7) FIG. 6 is a schematic perspective view of a further embodiment of a jointing assembly according to the present invention, in a specific operative configuration.

(8) With respect to FIGS. 1 to 3, a screen connector for electrical cables according to the present invention is indicated with numeral reference 10. The screen connector is preferably adapted to be used with high voltage electrical cables.

(9) As better explained in the following of the present description, the screen connector 10 can be used for connecting an electrical cable to the ground, or to a termination, or to another electrical cable through a joint, or to another electrical cable associated with another joint.

(10) The screen connector 10 comprises a conductive shield sock 11 (not visible in FIG. 1) extending about a longitudinal axis X-X.

(11) In a radially outer position with respect to the conductive shield sock 11, a shrinkable protective sleeve 12 made from an elastomeric material is provided. In FIG. 3 the protective sleeve 12 is shown in rest configuration, that is in radially collapsed state (before application over the conductive shield sock 11).

(12) The conductive shield sock 11 is adapted to be coaxially arranged onto a conductive screen of an electrical cable to provide electrical contact therewith. Similarly, the conductive shield sock 11 is adapted to be coaxially arranged onto a conductive screen of a cable joint or onto an end portion of a cable termination. If the termination has a conductive screen too, then the conductive shield sock 11 is adapted to be coaxially arranged onto said conductive screen.

(13) For application on a cable joint, termination or the like, the shrinkable protective sleeve 12 and the conductive shield sock 11 are held in a radially expanded state by a removable support element 13 arranged in a radially inner position with respect to the conductive shield sock 11.

(14) In the embodiment shown, the support element 13 is a tubular element defining a helically wound strip (either helically wound or cut in a solid tube). Said strip has a free end portion 13a adapted to be pulled in order to remove the support element 13 from the screen connector 10, causing the shrinkable protective sleeve 12 and the conductive shield sock 11 to radially collapse.

(15) In an alternative embodiment not shown, the support element is a rigid tubular element adapted to be moved out from the screen connector by displacement along the longitudinal axis X-X.

(16) As shown in FIGS. 2 and 3, two watertight elements 15a, 15b are provided at the opposite axial end of the support element 13 in a radially inner position with respect to the conductive shield sock 11, that is radially interposed between the support element 13 and the conductive shield sock 11. Preferably, the watertight elements are made by winding about the support element 13 at least one mastic tape.

(17) One or more metallic braids (here two metallic braids are shown, both indicated with 16) lie onto the conductive shield sock 11 so as to be radially interposed between said conductive shield sock 11 and the shrinkable protective sleeve 12. These metallic braids act as ground connectors. A single metallic braid 16 can be used in place of the two described above. No specific mechanical connection, such as welding, are required to maintain in the desired position the metallic braids 16. Indeed, maintenance of the desired position is achieved through the shrinking action exerted by the shrinkable protective sleeve 12.

(18) Two additional watertight elements are radially interposed between the conductive shield sock 11 and the shrinkable protective sleeve 12 at the opposite axial ends of the support element 13. Preferably, these additional watertight elements are made by winding mastic tapes 17a, 17b (see FIG. 3) about the conductive shield sock 11 at the same axial position of the watertight elements 15a, 15b (FIG. 2).

(19) In the embodiment shown in FIGS. 1-3, a connection element 19 is firmly arranged within a seat 18 associated with the metallic braids 16. The connection element 19 is in particular a mechanical connector but other types of connection elements, e.g. mechanical punches, can be used in place of the mechanical connector, such as for example plug-in electrical connectors or lugs.

(20) A different embodiment of a screen connector 10 in accordance with the present invention is shown in FIG. 4. Specifically, two screen connectors 10a, 10b are shown in FIG. 4, each one associated with a respective free end portion 50a, 50b of a joint 50 adapted to connect two electrical cables (not shown in this figure but shown in FIG. 5). The joint 50 of FIG. 4 is shown in a radially expanded state.

(21) The screen connectors 10a, 10b of FIG. 4 differ from that of FIGS. 1 to 3 in that a plug-in electrical connector 20a, 20b is used in place of the mechanical connector 19. In this case, each plug-in electrical connector 20a, 20b is associated with the metallic braids 16 by at least one elongated metallic arm 21a, 21b. Preferably, the metallic arms 21a, 21b are covered by a sheet of elastomeric material.

(22) FIG. 5 shows a joint 50 with two electrical cables 100a, 100b connected thereto. Here, differently from FIG. 4, two screen connectors 10a, 10b of the type above-described with reference to FIGS. 1 to 3 are used. Furthermore, the joint 50 is provided with an outer shield (described below) not shown in FIG. 4.

(23) The joint 50 of FIG. 5 is shown in a collapsed configuration over the electrical cables 100a, 100b.

(24) As shown in FIGS. 4 and 5, the joint 50 comprises a connector 51 extending about a longitudinal axis corresponding to the longitudinal axis X-X of the screen connectors 10a, 10b.

(25) The connector 51 is a socket connector, that is it comprises axially opposite end portions each provided with a seat adapted to house and lock into a desired axial position respective plug-in connectors 101a, 101b (FIG. 5) associated with a free end portion of a respective electrical cable.

(26) The joint 50 comprises a radially shrinkable sleeve 60, in a radially outer position with respect to the connector 51. The sleeve 60 can be made from heat or cold shrinkable dielectric materials. Preferably, the sleeve 60 is made of a cold shrinkable dielectric material, such as ethylene propylene diene monomer (EPDM) rubber.

(27) The sleeve 60 extends coaxially to the longitudinal axis X-X and has a length greater than that of the connector 51. The connector 51 is centrally arranged within the sleeve 60 along the longitudinal axis X-X so as to have a symmetrical arrangement of the sleeve 60 about the connector 51 along the longitudinal axis X-X.

(28) The sleeve 60 comprises, at a radially inner portion thereof, a first cylindrical insert 61 made from a conductive or semi-conductive material. Throughout the following description, the insert 61 will be indicated as electrode.

(29) Preferably, the electrode 61 is made from a cold shrinkable semi-conductive material. More preferably, such a material is rubber EPDM.

(30) The electrode 61 extends coaxially to the longitudinal axis X-X and has a length greater than that of the connector 51 and lower than that of the sleeve 60. The electrode 61 is symmetrically arranged with respect the connector 51 and the sleeve 60 along the longitudinal axis X-X.

(31) The sleeve 60 further comprises, at each of the end portions thereof, a respective second cylindrical insert 62a, 62b, made from a conductive or semi-conductive material. Throughout the following description, the inserts 62a, 62b will be indicated as deflectors.

(32) The deflectors 62a, 62b cooperate with the electrode 61 to control the electrical field within the sleeve 60, in particular to avoid the presence of areas with high concentration of electrical field, wherein undesired electrical discharges and breakdowns could occur.

(33) Preferably, the deflectors 62a, 62b are made from a cold shrinkable semi-conductive material. More preferably such a material is EPDM or silicone rubber. Alternatively, the deflectors 62a, 62b are made from a high permittivity material.

(34) Each of the deflectors 62a, 62b extends coaxially to the longitudinal axis X-X and axially projects inside the sleeve 60 toward the electrode 61 so that the radially inner portion of the sleeve 60 is defined, moving from the central portion toward each of the end portions thereof, by the electrode 61, the dielectric material of the sleeve 60 and the deflector 62a, 62b.

(35) In the joint 50 of FIG. 4 the electrode 61 and the deflectors 62a, 62b are incorporated into the dielectric material of the sleeve 60.

(36) In an alternative embodiment (not shown), the electrode and the deflectors are not incorporated into the dielectric material of the sleeve 60, but are arranged in a radially inner position with respect to the radially inner surface of the sleeve 60.

(37) As shown in FIG. 4, the sleeve 60 is initially held in a radially expanded state by two support elements 70a, 70b which are arranged in a radially inner position with respect to the sleeve 60, the electrode 61 and the deflectors 62a, 62b.

(38) In this configuration, the support elements 70a, 70b are associated with each other by a connecting element 71 adapted to hold the support elements 70a, 70b within the sleeve 60. Only the opposite free end portions of the connecting element 71 are visible in FIG. 4.

(39) After having mechanically and electrically coupled the two electrical cables 100a, 100b to the connector 51, the support elements 70a, 70b are axially removed from the opposite end portions of the sleeve 60 along opposite directions, thus causing the sleeve 60, together with the electrode 61 and the deflectors 62a, 62b, to shrink onto the electrical cables 100a, 100b, so as to take the configuration shown in FIG. 5. In order to remove the support elements 70a, 70b, the aforementioned connecting element 71 is broken.

(40) In the embodiment shown in FIG. 4, each support element 70a, 70b comprises a tubular rigid body made from a plastic material. Preferably, each of the tubular rigid body is made of a charged homopolymer polypropylene.

(41) In an alternative embodiment (not shown) of the jointing assembly, each support element is a tubular element defining a helically wound strip (either helically wound or cut in a solid tube). The strip is adapted to be removed from the respective end portion of the sleeve by pulling a free end portion of the strip.

(42) As better shown in FIG. 5, the joint 50 further comprises, in a radially outer position with respect to the sleeve 60, a first shield 80. The shield 80 has a length substantially equal to that of the sleeve 60.

(43) Preferably, the shield 80 is made of a two-layer sheath including an radially inner layer and a radially outer layer.

(44) The radially inner layer is preferably made from a dielectric material, more preferably rubber EPDM, while the radially outer layer is preferably made from a semi-conductive material, more preferably rubber EPDM.

(45) In a radially outer position with respect to the first shield 80, a metallic screen 90 is provided. The screen 90 has a length greater than that of the sleeve 60 and is preferably made of tinned copper.

(46) The joint 50 further comprises, in a radially outer position with respect to the screen 90, a second shield 95 having preferably a length substantially equal to that of the screen 90.

(47) Preferably, the shield 95 is made of a two-layer sheath, that is it includes a radially inner layer made from a dielectric material and a radially outer layer made from a semi-conductive material. More preferably, the same material of the shield 80 is used.

(48) As far as the electrical cables 100a, 100b are concerned, as shown in FIG. 5, the conductors of each electrical cable 100a, 100b are covered by an insulating layer 102a, 102b. A conductive screen 103a, 103b is coaxially applied at a radially outer position to the insulating layer 102a, 102b. The conductive screen 103a, 103b is in turn covered with at least one protective sheath 104a, 104b of electrically insulating plastic or elastomeric material.

(49) Preferably each electrical cable 100a, 100b further comprises at least one semi-conductive layer 105a, 105b radially interposed between the insulating layer 102a, 102b and the conductive screen 103a, 103b.

(50) In the embodiment of FIG. 5, the conductive screen 103a, 103b of the electrical cables 100a, 100b are electrically connected to each other through the metallic screen 90 of the joint 50.

(51) To this end, the opposite end portions of the second shield 95 of the joint 50 are folded back toward each other (or, in an alternative embodiment not shown, they are held in a radially expanded state by respective removable rigid bodies) and each of the opposite free end portions of the metallic screen 90 is arranged in a radially outer position with respect to a respective conductive screen 103a, 103b of a respective electrical cable 100a, 100b.

(52) Advantageously, each screen connector 10a, 10b is in turn arranged in a radially outer position with respect to the aforementioned free end portions of the metallic screen 90 of the joint 50 so that, upon removal of the support element 13 of the screen connector 10a, 10b, the shrinkable protective sleeve 12 and the conductive shield sock 11 of the screen connectors 10a, 10b shrink onto the metallic screen 90 of the joint 50 and the conductive screen 103a, 103b of the electrical cable 100a, 100b, obtaining the desired electrical contact between conductive screen 103a, 103b, metallic screen 90 and conductive shield sock 11.

(53) Afterwards, the opposite end portions of the second shield 95 of the joint 50 are unfolded to fully cover the screen connectors 10a, 10b, leaving out just the connection elements 19.

(54) The embodiment of FIG. 5 allows each of the conductive screen 103a, 103b of the electrical cables 100a, 100b connected to the joint 50 to be connected through the screen connectors 10a, 10b to the ground.

(55) The embodiment of FIG. 5 also allows each of the conductive screen 103a, 103b of the electrical cables 100a, 100b connected to the joint 50 to be connected to an electrical cable connected to another joint.

(56) In a different embodiment not shown, the screen connectors 10a, 10b are associated with a joint as that of FIGS. 4 and 5, the metallic screen 90 is provided, but it is interrupted. In this case, the reciprocal electrical connection between the conductive screen 103a, 103b of the two electrical cables 100a, 100b can be achieve by connecting to each other the plug-in electrical connectors 20a, 20b associated with each other. Of course, in this case one of the electrical connectors 20a, 20b could be a male connector and the other one could be a female connector.

(57) FIG. 6 shows a further embodiment. In this embodiment the screen connector 10 is associated with a termination 200 which is in turn associated with an electrical cable 100.

(58) The termination 200 comprises a shrinkable body 201 extending about a longitudinal axis X-X. The shrinkable body 201 is made from dielectric material.

(59) The shrinkable body 201 comprises a portion 210 shaped so as to define a plurality of fins (all indicated with 210a).

(60) A deflector 262 for controlling the electrical field is incorporated in the material of the shrinkable body 201.

(61) The electrical cable 100 is inserted in an axial cavity of the shrinkable body 201 and is connected with a plug-in connector 202 housed in a cap 203 associated with a free end portion 201a of the shrinkable body 201. The cap 203 is made of an elastomeric material.

(62) On the axially opposite free end portion 201b of the shrinkable body 201a screen connector 10 of the above-described is provided. In particular, an end portion of the screen connector 10 is arranged in a radially inner position with respect to the end portion 201b of the shrinkable body 201 so as to provide an electrical connection between the conductive shield sock 11 of the screen connector 10 and the conductive screen of the electrical cable 100. By this way, the electrical cable 100 can be connected to the ground.

(63) The shrinkable body 201 is held in a radially expanded state by a removable support element (not visible) arranged in a radially inner position thereto. When this support element is removed, the shrinkable body 201 collapses onto the electrical cable 100. The removable support element can be a tube cut into a helically wound strip or a removable rigid tubular element, similarly to what stated above with respect to the removable support element of the screen connector 10 and of the joint 50.

(64) The termination may or not be provided with a conductive screen. Should the conductive screen be provided, the conductive shield sock 11 of the screen connector 10 is preferably arranged in a radially outer position with respect to the conductive screen of the termination.

(65) The skilled person will understand that, starting from the above described different embodiments of the jointing assembly of the present invention, a plurality of further different embodiments can be foreseen by combining in different ways the various features described above. All these embodiments are indeed encompassed by the present invention and are within the scope of protection defined by the attached claims.