REPAIR AND REPLACEMENT OF HIGH VOLTAGE CABLES AND JOINTS

Abstract

A method of repairing or replacing a joint for high voltage polymer cables or a high voltage polymer cable (1c), comprises the steps of: a) removing a section to be replaced of the joint or the high voltage polymer cable (1c) such that two cable ends (1a, 1b) result, whereby the two cable ends (1a, 1b) are oriented toward each other and whereby the two cable ends (1a, 1b) are positioned in a separation distance (20) from each other and whereby each cable end (1a, 1b) comprises a cable conductor (10a, 10b), b) preparing the two cable ends (1a, 1b) by exposing the cable conductors (10a, 10b) of both cable ends (1a, 1b) over a first length c) connecting the two cable conductors (10a, 10b) with a connection piece (3) which comprises two receiving sections (31a, 31b) and a centre section (30) and which is electrically conducting, whereby a length of the centre section (30d) corresponds to the separation distance (20) and whereby the cable conductors (10a, 10b) are mounted in such a way to the receiving sections (31a, 31b) that a mechanical and an electrically conducting connection is established.

Claims

1-20. (canceled)

21. A method of repairing or replacing a joint for high voltage polymer cables or a high voltage polymer cable, comprising the steps of: a) removing a section to be replaced of the joint or the high voltage polymer cable such that two cable ends result, wherein the two cable ends are oriented toward each other and wherein the two cable ends are positioned in a separation distance from each other and whereby each cable end comprises a cable conductor; b) preparing the two cable ends by exposing the cable conductors of both cable ends over a first length; c) connecting the two cable conductors with a connection piece which comprises two receiving sections and a centre section and which is electrically conducting; wherein a length of the centre section corresponds to the separation distance; and wherein the cable conductors are mounted to the receiving sections in such a way that a mechanical and an electrically conducting connection is established.

22. The method according to claim 21 further comprising the steps of: exposing at each of the two cable ends: an insulating layer; and an outer semiconducting layer surrounding the insulating layer; placing a stress control body comprising two deflectors and a shield electrode around the cable ends connected with the connection piece; wherein each of the two deflectors contacts a different one of the exposed outer semiconducting layers; and wherein a length of the shield electrode is greater than the length of the connection piece such that the shield electrode touches the insulating layer of both cable ends and surrounds the connection piece completely.

23. The method according to claim 22 further comprising the steps of: providing a prefabricated stress control body comprising two deflectors and a shield electrode; and exposing the insulating layer of a first and a second cable end for a length which essentially equals the distance between a contact region of the deflector and a contact region of the shield electrode; and exposing the outer semiconducting layer of the first cable end for such a length that a sum of the lengths of the exposed outer semiconducting layer of the first cable end and the exposed insulating layer of the first cable end is greater or equal to a length of the prefabricated stress control body; exposing the outer semiconducting layer of the second cable end for a length greater than the extent of the contact region of the deflector; slipping the prefabricated stress control body onto the first cable end; connecting the two cable conductors with the connection piece; placing a filling, which is electrically conducting or semiconducting, around the connection piece, wherein the outer diameter of the filling is essentially constant and essentially equal to the outer diameter of the insulating layer of the two cable ends; and slipping the prefabricated stress control body in a position where the contact region of each of the deflectors is located onto a different one of the outer semiconducting layers and where the shield electrode surrounds the connection piece and the filling and is partially located onto both of the insulating layers.

24. The method according to claim 22, further comprising the steps of: exposing at each of the two cable ends a metal sheath; and placing a casing around the stress control body covering the connection piece; and connecting the casing in a fluid tight manner to the metal sheath of both cable ends.

25. Method according to claim 24, wherein the casing comprises two casing parts made of metal and a casing tube made of electrically insulating material; wherein the two casing parts have both a first opening of a diameter essentially equal to the diameter of the metal sheath of the cable ends and a second opening greater than the greatest diameter of the stress control body; and wherein the casing tube has an inner diameter greater than the greatest diameter of the stress control body and an outer diameter greater than the second opening of the two casing parts; and wherein the method comprises the steps of: placing on each of the two cable ends one casing part before placing the stress control body anywhere on one of the cable ends; placing at least parts of the casing tube on one of the cable ends before connecting the two cable conductors with the connection piece; after placing the stress control body in a position where the contact region of each deflector is located on a different one of the outer semiconducting layers and where the shield electrode surrounds the connection piece, bringing the two casing parts and the casing tube together such that both casing parts contact the casing tube on different ends; and connecting every one of the second openings of the two casing parts to a different end of the casing tube in a fluid tight way.

26. The method according to claim 22, further comprising the steps of: placing a protection box around the stress control body covering the connection piece or around the casing; wherein the protection box has such an extent that it touches outer jackets of each of the two cable ends such that there is a fluid-tight connection between the protection box and the outer jacket of every one of the cable ends; filling the protection box with a casting compound which is liquid during filling; and curing the casting compound such that it becomes a solid.

27. The method according to claim 22, further comprising the steps of: exposing at each of the two cable ends a metal sheath; connecting at least one screen conductors to the metal sheath or wires of a net of each of the cable ends in a screen conductor-connecting region; and covering the stress control body, the screen conductors and the screen conductor-connecting region of both cable ends and the section of the two cable ends between the screen conductor-connecting regions with a water barrier foil which is connected to the exposed metal sheath of both cable ends; wherein the screen conductors connected to one cable end are either the same as the screen conductors connected to the other cable end; or electrically connected to the screen conductors which are connected to the other cable end.

28. The method according to claim 21, wherein the step of removing the section to be replaced of the joint comprises the following steps: removing, if present, a protection box of the joint; removing, if present, a casting compound of the joint; removing, if present, a casing of the joint; removing, if present, a stress control body of the joint; and removing a connector connecting the cable conductors in the joint.

29. The method of repairing or replacing a high voltage polymer cable according to claim 21, wherein the step of removing the section to be replaced of the high voltage polymer cable comprises the following step: cutting the cable on both sides of the section to be replaced and removing the section to be replaced.

30. A connection piece for connection two cable conductors of high voltage polymer cables in a method of repairing or replacing a joint or a high voltage polymer cable, the connection piece comprising two receiving sections and a centre section, wherein a length of the centre section is greater or equal to 10 cm and corresponds to a separation distance between two cable ends to be connected.

31. A connection piece for connecting two cable conductors of high voltage polymer cables in a method of repairing or replacing a joint or a high voltage polymer cable, the connection piece comprising two receiving sections and a centre section, wherein the centre section and at least one of the receiving sections are equipped with coupling means which allow to establish a mechanical and electrically conducting connection between the at least one receiving section and the centre section, and wherein a length of the centre section is greater or equal to 10 cm and corresponds to a separation distance between two cable ends to be connected.

32. The connection piece according to claim 31, wherein the coupling means are a threaded hole and a threaded bolt.

33. The connection piece according to claim 31, wherein the centre section comprises two or more centre section pieces which are all equipped with coupling means to establish a mechanical and electrically conducting connection.

34. The connection piece according to claim 31, wherein there are two receiving sections equipped with coupling means in the form of threads, wherein the handedness of the threads of the two receiving sections is different from each other and wherein the centre section comprises a central piece, wherein the central piece comprises two threads of different handedness and wherein, if there are adapter pieces, each adapter piece comprise two threads with same handedness.

35. A high voltage cable repair joint comprising: a) a connection piece; and b) a stress relief body comprising two deflectors (61a, 61b) and one shield electrode wherein the shield electrode has a length of more than 20 cm and a length which is greater than the length of the connection piece.

36. The high voltage cable repair joint according to claim 35 further comprising a casing with a length twice the length of the stress relief body.

37. The high voltage cable repair joint according to claim 36 further comprising: a centering device made of electrically insulating material, wherein the centering device is located inside the casing between one end of the casing and the stress relief body and wherein the centering device comprises a duct to receive a high voltage polymer cable, and whereby the centering device has an outer diameter which equals the inner diameter of the casing such that the centering device can support a high voltage polymer cable to run along a longitudinal axis of the casing.

38. The high voltage cable repair joint according to claim 35 further comprising: one or more screen conductors and a layer made of water barrier foil surrounding the stress relief body and the screen conductors.

39. Use of a connection piece in a method of repairing or replacing a joint or a cable according to claim 21, the connection piece comprising two receiving sections and a centre section with a length corresponding to a separation distance between two cable ends.

40. Use of a stress control body in a method of repairing or replacing a joint or a cable according to claim 22, said stress control body comprising two deflectors and a shield electrode around the cable conductors connected with the connection piece, wherein the length of the shield electrode is greater than the length of the connection piece.

Description

[0156] The drawings used to explain the embodiments show:

[0157] FIG. 1a A faulty high voltage polymer cable

[0158] FIG. 1b A sketch indicating the cuts necessary to remove the section to be replaced of the faulty high voltage polymer cable

[0159] FIG. 1c The two cable ends with exposed cable conductors

[0160] FIG. 1d The connection piece with two receiving sections and a centre section

[0161] FIG. 1e The two cable ends connected with the connection piece

[0162] FIG. 2a A faulty joint for high voltage polymer cables

[0163] FIG. 2b A sketch indicating the cuts necessary to remove the section to be removed of the faulty joint

[0164] FIG. 2c The two cable ends with exposed cable conductors

[0165] FIG. 2d The connection piece with two receiving sections and a centre section

[0166] FIG. 2e The two cable ends connected with the connection piece

[0167] FIG. 3a A connection piece with coupling means in the form of threads on one of the receiving sections and on the centre section

[0168] FIG. 3b A first embodiment of a connection piece with a centre section comprising centre section pieces in the form of one central piece and two adapter pieces.

[0169] FIG. 3c A second embodiment of a connection piece with a centre section comprising centre section pieces in the form of one central piece and two adapter pieces.

[0170] FIG. 4 A simple repair joint

[0171] FIG. 5 A first repair joint of the straight-through type

[0172] FIG. 6 A repair joint of the cross-linked type

[0173] FIG. 7a A second repair joint of the straight-through type

[0174] FIG. 7b A close-up of the screen conductor-connecting region of the second repair joint shown in FIG. 7a

[0175] FIG. 8 A stress control body with an inhomogeneous shield electrode

[0176] In the figures, the same components are given the same reference symbols.

[0177] FIGS. 1a to 1d illustrate the method to repair a faulty high voltage polymer cable 1c. The method to replace a part of a high voltage polymer cable is analogue to the one depicted here with the only difference, that there is no defect but another reason for a local replacement. FIG. 1a shows a sketch of the faulty high voltage polymer cable 1c. The place where the defect occurred is marked by a thunderbolt. FIG. 1b illustrates that the faulty high voltage polymer cable 1c is cut 2 before and behind the defect. The section to be replaced of the faulty high voltage polymer cable 1c is the part between the two cuts 2. This section to be replaced is removed. Two cable ends 1a and 1b remain and they are shown in FIG. 1c. The cable conductors 10a and 10b of the two cable ends 1a and 1b are exposed. The distance between the two cable ends 1a and 1b is the separation distance 20. FIG. 1d shown a connection piece 3. It is made of an electrically conducting material such as copper or a copper alloy. The connection piece 3 has two receiving sections 31a and 31b and a centre section 30 in between. The centre section 30 has the shape of a cylinder. The two receiving sections 31a and 31b have the shape of hollow cylinders. The length of the centre section 30d equals the separation distance 20. In FIG. 1e, the connection piece 3 is used to connect the two cable conductors 10a and 10b of the two cable ends 1a and 1b. The cable conductors 10a and 10b are placed inside the two receiving sections 31a and 31b and fixed by crimping to them. An electrically conducting connection is established by the connection piece 3 which replaces the section to be replaced and therefore the high voltage polymer cable is repaired.

[0178] FIGS. 2a to 2e illustrate the method to repair a faulty joint for high voltage polymer cables 100c. Again, a similar method can be used to replace a joint with the only difference that there is no defect. FIG. 2a depicts the faulty joint 100c. The faulty joint 100c comprises a protection box 5, a casing 4 and a stress control body 6 and a connector 3x. The connector 3x connects two cable conductors 10a and 10b of two cable ends 1a and 1b. The stress control body 6 is arranged around the connector 3x. A casing 4 encloses the stress control body 6. The protection box 5 encloses the casing 4. A cast material 7 fills the volume between the protection box 5 and the casing 4. The faulty joint 100c has a defect marked with a thunderbolt. The defect is located at the connector 3x.

[0179] FIG. 2b shows the situation after the removal of the protection box 5, the cast material 7, the casing 4 and the stress control body 6. There are two cable ends 1a and 1b with two cable conductors 10a and 10b connected with a connector 3x. The connector 3x is faulty. Both cable ends 1a and 1b are cut 2 at a place close to the connector 3x but before the cable conductors 10a and 10b enter the connector 3x. The section between the two cuts 2 is the section to be replaced. The section to be replaced is removed.

[0180] FIG. 2c depicts the situation after the removal of the section to be replaced and after exposing the cable conductors 10a and 10b again. There is now a separation distance 20 between the two cable ends 1a and 1b.

[0181] FIG. 2d shows the connection piece 3. It comprises a centre section 30 and two receiving section 31a and 31b. It is similar to the connection pieces shown in FIG. 1d which the only exception being the length of the centre section 30: The length of the centre section 30 of the connection piece 3 shown in FIG. 2d equals the separation distance 20 shown in FIG. 2c. Further, the receiving sections 31a and 31b are equipped with threads of opposite handedness on their inside.

[0182] FIG. 2e shows the cable ends 1a and 1b connected with the connection piece 3. End caps comprising threads matching the ones of the receiving sections 31a and 31b are mounted onto the cable conductors 10a and 10b. The connection piece 3 is placed between the two cable ends 1a and 1b and was fixed to the cable conductors by rotating is around its longitudinal axis and thereby screwing it onto the cable conductors 10a and 10b.

[0183] FIG. 3a shows a connection piece 3 which consists of a centre section 30 and a receiving section 31a with coupling means. The coupling means on the centre section 30 has the form of a threaded hole 110a and the receiving section 31a has a coupling mean in the form a threaded bolt 110b. The receiving section 31b and the centre section 30 form one integral part. The threaded bolt 110b can be screwed into the threaded hole 110a and thereby the receiving section 31a can be coupled to the centre section 30.

[0184] FIG. 3b depicts a first embodiment of a connection piece 3 with a centre section 30 comprising centre section pieces 301 in the form of one central piece 301a and two adapter pieces 301b, 301c. In this embodiment, the two adapter pieces 301b and 301c are both equipped with a threaded bolt and a threaded hole. The two receiving sections 31a and 31b are both equipped with a threaded bolt. The central piece 301a is equipped with two threaded holes. The handedness of the threaded holes of the central piece 301a is different from each other. Also the threaded bolts of the two receiving sections 31a and 31b differ in their handedness. All threads located on one adapter piece 301b or 301c have the same handedness. In the embodiment shown in FIG. 3b, the threads on all adapter pieces 301b and 301c have the same handedness. Due to the different handedness of the threads in the central piece 301a and of the threads of the receiving sections 31a and 31b, rotating the central piece 301a around its longitudinal axis tightens or loosens the connection to both receiving sections 31a and 31b simultaneously. The adapter pieces 301b and 301c are designed in such a way that more, similar adapter pieces can be added to make the centre section 30 longer or they can be omitted to shorten the centre section 30.

[0185] FIG. 3c depicts a second embodiment of a connection piece 3 with a centre section 30 comprising centre section pieces 301 in the form of one central piece 301a and two adapter pieces 301b and 301c. In this embodiment, all threads have the same handedness. The receiving section 31a is equipped with a threaded outer surface. The central piece 301a has the shape of a hollow cylinder with a threaded inner surface. The inner diameter of the central piece 301a and the outer diameter of the receiving section 31a as well as their threads are designed in such a way that the central piece 301a can be screwed onto the receiving section 31a. The adapter piece 301b has an outer surface which comprises partially a thread and a threaded hole. The outer diameter of the adapter piece 301b is such that the central piece 301a can be screwed onto its threaded part and slipped over the part without threaded surface. The adapter piece 301c comprises a threaded bolt and a threaded hole. The receiving section 31b comprises a threated bolt.

[0186] This second embodiment can be mounted as follows on the two cable ends: The central piece 301a is screwed onto the adapter piece 301b such that it does not extend over the adapter piece 301b on any end of it. The receiving ends 31a and 31b are mounted onto the cable conductors of the cables to be connected. A suitable number of adapter pieces similar to 301c are screwed onto the receiving end 31b. The adapter piece 301b is screwed onto the other adapter pieces 301c, or if none was needed, directly onto the receiving end 31b. In this situation, the separation distance between the two cable ends is essentially filled with parts of the centre section 30. In this situation, the central piece 301a is screwed off the adapter piece 301b and at the same time screwed onto the receiving section 31a. Thereby, the connection piece 3 becomes one electrically well conducting part with a centre section 30 of the desired length.

[0187] FIG. 4 shows a simple repair joint 100. This joint 100 is symmetric and therefore only the connection of the first cable end 1a is described. The second cable end and its connection is analogue.

[0188] The conductor 10a of the first cable end 1a is exposed over a first length. This is followed by a section in which the insulating layer 12a of the first cable end 1a is exposed over a second length. This is followed by a section in which the outer semiconducting layer 13a of the first cable end 1a is exposed over a third length. This is followed by a section in which the outer semiconducting layer 13a of the first cable end 1a is wrapped with electrically conducting tape followed by electrically insulating tape to create an enhanced outer semiconducting layer 131a.

[0189] There is further a connection piece 3. It has two receiving sections. The receiving section is slightly shorter than the first length over which the cable conductor 10a of the first cable end 1a is exposed. The cable conductor 10a is placed inside the receiving section. There is a short distance between the insulating layer 12a and the connection piece 3. This distance is filled with a semiconducting filling tape 32s such that outer diameter of this filled section equals the outer diameter of the connection piece 3. The outer diameter of the connection piece 3 is smaller than the outer diameter of the insulating layer 12a of the cable ends 1a. A filling tube 32t is placed between the ends of the insulating layers 12a, 12b of the two cable ends 1a and 1b. The outer diameter of the filling tube 32t equals the outer diameter of the insulating layer 12a and 12b. The space between the filling tube 32t and the connection piece 3 or the semiconducting filling tape 32s is filled with conducting filling tape 32r.

[0190] A stress control body 6 surrounds this setup. The stress control body 6 has the shape of a hollow cylinder with two outwardly tampering ends. The stress control body 6 comprises a shield electrode 60 and two deflectors 61a and 61b. The shield electrode 60 and the two deflectors 61a and 61b are made of semiconducting material such a silicone rubber with carbon black particles. The rest of the stress control body 6 is made of electrically insulating material such a silicone rubber. The shield electrode 60 has the shape of a tube with rounded edges. Its length is greater than the distance between the ends of the insulating layers 12a, 12b of the two cable ends 1a and 1b. The shield electrode 60 contacts and covers the filling tube 32t and is therefore, during operation, on the high voltage potential of the cable conductors 10a, 10b. The deflectors 61a have the shape of round cones with their smaller diameter pointing outwards. In the region of their smallest diameter, the deflectors 61a, 61bc contact the outer semiconducting layers 13a, 13b of the two cable ends. The deflectors 61a, 61b are located at the ends of the stress control body 6. Outside of the stress control body 6, there is the enhanced outer semiconducting layer 131a. The enhanced outer semiconducting layer 131a ensures a reliable grounding of the outer semiconducting layer 13a and the deflector 61a via the metal sheath of the cable. The metal sheath of the cable is not shown in this Figure.

[0191] The stress control body 6 is in one embodiment covered with an electrically conducting or semiconducting layer which is also grounded. This ensures that the electric field is restricted to the inside of the stress control body 6.

[0192] FIG. 5 shows a first repair joint of the straight-through type 100a.

[0193] The inner part resembles the simple repair joint described and shown in FIG. 4.

[0194] The FIG. 5 shows more of the cable ends 1a and 1b than FIG. 4. The section with the enhanced outer semiconducting layer 131a is followed by a section where the metal sheath 14a, 14b is exposed. Further away from the connection piece 3, both cable ends 1a, 1b have their outer jacket 15a, 15b.

[0195] On the first cable end 1a, the section with the enhanced outer semiconducting layer 131a is approximately as long as the stress control body 6. On the second cable end 1b, the section with the enhanced outer semiconducting layer 131b is much shorter with a length similar to the length over which the outer semiconducting layer 13b is exposed.

[0196] A centering device 8 is placed around the first cable end 1a, in the middle of the section with the enhanced outer semiconducting layer 131a.

[0197] A casing 4 encloses the volume which comprises both enhanced outer semiconducting layers 131a and 131b, the stress control body 6 and the centering device 8. The casing comprises a first and a second casing part 4a and 4b as well as a casing tube 4c. The first and the second casing part 4a and 4b are connected with a seal 4d to the metal sheaths 14a and 14b of the cables ends 1a and 1b respectively. The casing parts 4a and 4b are made of metal, preferably of copper. They are connected with the casing tube 4c in a fluid-tight and electrically insulating manner. The seal 4d established a fluid tight and electrically conducting connection between the metal sheath of a cable end and the casing part mounted to it.

[0198] The two casing parts 4a and 4b are connected by a grounding connector 9 in an electrically conducting way.

[0199] The casing 4 with its seals 4d and the grounding connector 9 are enclosed by a protection box 5. The protection box 5 is made of plastic. It surrounds the outer jacket 15a and 15b of both cable ends 1a and 1b.

[0200] The volume between the casing 4 and the protection box 5 is filled with casting compound 7 which becomes solid after casting and protects the inner parts of the joint from mechanical damages and water.

[0201] FIG. 6 discloses a repair joint of the cross-linked type 100b. It resembles the repair joint of the straight-through type 100a shown in FIG. 5. The two types differ in the arrangement of the grounding connectors 9, 9a, 9b: In FIG. 5, there was only one grounding connector 9 which establishes an electrically connection between the two casing parts 4a and 4b.

[0202] In FIG. 6 however, a first grounding connector 9a is connected to the first casing part 4a and a second grounding connector 9b is connected to the second casing part 4b. Both grounding connectors, 9a and 9b, extend outside of the protection box 5. Therefore only part of them is enclosed by the casting compound 7.

[0203] FIG. 7a shows a second repair joint of the straight-through type 100c and FIG. 7b shows a close-up of the screen conductor-connecting region 151 of this second repair joint 100c.

[0204] The innermost part of the second repair joint 100c is essentially the same as the innermost part of the first straight-though repair joint 100a and the cross-bonding type 100b. The innermost part comprises the connection part 3, the stress control body 6 and the way the cable ends are prepared. The following description focuses therefore on the outer part, which distinguishes the first and the second repair joint.

[0205] In the second repair joint, the two functions of the casing 4 are replaced by the screen conductors 120 and the water barrier foil 130: The grounding of the outer semiconductive layer 13 is enabled by the screen conductors 120 and the water barrier function is ensured by the water barrier foil 130. Consequently, there is no casing 4 needed or shown in this embodiment.

[0206] FIGS. 7a and 7b show the situation of cables comprising copper wires forming a net 141 beneath the metal sheath 14 being connected.

[0207] The connection between the metal sheath 14 of the cable and the wires of the net 141 and the screen conductors 120 is realized as follows:

[0208] An inner layer of copper braiding surrounds the metal sheath 14 in the screen conductor-connecting region 151. In this region, the inner layer of copper braiding fills the distance between the metal sheath 14 and the protection tube 150. The protection tube 150 is made of brass and protects the soft metal sheath 14 of the cable, which is often made of lead, from deformation and damages due to the fixing of the screen conductors 120.

[0209] The wires of the net 141 are in the unprepared cable beneath the metal sheath 14 in the shown embodiment. During the preparation of the cable end, the wires of the net 141 are exposed for a distance of about the length of the screen conductor-connecting region 151. After the installation of the protection tube 150 the exposed wires of the net 141 are folded back onto the protection tube 150.

[0210] The back-folded wires of the net 141 are fixed by a copper wire wrapped around them.

[0211] In this case the wires of the net 141 are guided through the inner layer of copper braiding by using a tape to construct the inner layer of copper braiding and by running this tape between two parallel running wires of the net 141 in the region where they are bent

[0212] The screen conductors 120 are arranged on the copper wire fixing the back-folded wires of the net 141. The number of screen conductors 120 depends on the conducting cross-section needed in the application at hand. Typically, three screen conductors 120 are used. The screen conductors 120 are evenly distributed around the circumference of the wrapped protection tube 150.

[0213] The screen conductors 120 are fixed in the screen conductor-connecting region 151 by fixing means in the form of steel clamps. The clamps press the screen conductors 120 onto the protection tube 150 and the wires surrounding it. Thereby, a good electric and mechanical contact between the wires of the net 141, the protection tube 150 and the screen conductors 120 is ensured.

[0214] The same screen conductors 120 are fixed in the same way in both screen conductor-connecting regions 151. Thereby, a good electric contact is established between the metal sheaths 15 and the nets of the two connected cable ends. In another embodiment, the same number of screen conductors 120 are fixed on both cable ends and each of the screen conductors 120 connected to one cable end is connected to one of the screen conductors 120 connected to the other cable end in such a way that a good electric contact is established.

[0215] An outer layer of copper braiding surrounds the screen conductor-connecting region 151, the screen conductors 120 and the inner layer of the copper braiding.

[0216] The inner layer of copper braiding, the screen conductors 120 and the outer layer of copper braiding extend from one screen conductor-connecting region 151 to the other and surround in between the stress control body 6 mounted on the connection piece 3. In the embodiment of FIG. 7a, the outer layer of copper braiding covers the screen conductor-connecting region 151.

[0217] The inner and the outer layer of copper braiding are realised by wrapping braided copper around the inner structures. The screen conductors 120 run essentially parallel to the longitudinal axis of the connected cable conductors but follow the outer shape of the stress control body 6.

[0218] The resulting assembly is wrapped with a semiconducting tape. The water barrier foil 130 is applied on top of the semiconducting tape. In this embodiment, the water barrier foil 130 is applied in the form of rectangular pieces of an aluminium foil which are arranged in an overlapping way to ensure the desired fluid tightness. In another embodiment, an aluminium tape is wrapped in an overlaying manner onto the semiconducting tape and forms the water barrier foil 130.

[0219] The outermost layer is a protection layer 140 in the form of two overlapping heat shrink tubes. A sealing tape is arranged between parts of the outer jacket 15 and the heat shrink tube in order to ensure a fluid tight connection between the protection layer 140 and the outer jacket 15 of the cables.

[0220] FIG. 8 shows a stress control body 6c with an inhomogeneous shield electrode 60c. This stress control body 6c can replace the stress control body 6 comprising a homogeneous shield electrode 60 as shown for example in FIG. 4. The inhomogeneous shield electrode 60c comprises two semiconducting regions 602a, 602b which have both the shape of circular tubes with rounded ends and which are both homogeneously semiconducting. They have the same diameter and the same length. The two semiconducting regions 602a, 602b are arranged in a distance 602c of less than 10 mm, in this case, they are arranged in a distance 602c of 5 mm. Both semiconducting regions 602a, 602b are arranged in such a way that they will contact the same connection piece 3 respectively the same filling once the stress control body 6c is mounted in the finished repair joint. Therefore, they will be on the same electric potential even though they are separated by insulating material.

[0221] The resulting inhomogeneous shield electrode 60c has the shape of the convex hull of the two semiconducting regions 602a, 602b and this is in the case at hand a circular tube with rounded ends having a diameter equal to the diameter of the semiconducting regions 602a,b and a length 601 equal to the sum of the lengths of the two semiconducting regions and the distance 602c between them.

[0222] The remaining features of the stress control body 6c are the same as in the stress control body 6 described above.

[0223] In summary, it is to be noted that the different types of connection pieces can be used in the different types of repair joints. Further, different ways to connect cable conductors to receiving sections can be used in different types of connection pieces. It is possible to omit the protection box. It is also possible to omit the casting compound. Instead of using an enhanced outer semiconducting layer, the metal sheath can extend further inside the casing. It is also possible that the enhanced outer semiconducting layer is omitted and the semiconducting layer is exposed in this region or that the semiconducting layer is wrapped with a conducting or semiconducting tape. It is possible that the region of the enhanced outer semiconducting layer is of the same length on both cable ends. In this case, the casing and the protection box can be shorter.

[0224] The connection piece can use coupling means different than threads, for example a clip system or an interlocking tongue-and-groove system. Different types of coupling means can be used in a connection piece.