SE1400281A1 - Högspänningskabel för växelström innefattande en armeringsövergångsskarv, och framställning därav - Google Patents

Description

15 20 25 from the first armor type; and providing a joint interconnecting the first armor type with the second armor type, the joint comprising a non-metallic armor part.

The method enables the adaptation of the HVAC cable to thermally less favorable places by providing an armor layer that comprises, along a part thereof, of a material that is more suitable for such thermally less favorable places, and an armor transition joint that avoids corrosion problems between the different armor types of the HVAC cable, and also ensures that the armor provides ground connection.

In an embodiment, the providing of a joint comprises attaching the first armor type to a first joint sleeve and the second armor type to a second joint sleeve; and providing the HVAC cable with a non-metallic armor along the distance G between the first and second armor types.

In a variation of the above embodiment, the attaching comprises welding the first and second armor types to the first and second joint sleeves, respectively.

In an embodiment, the method comprises electrically interconnecting the first armor type with the second armor type by means of a cable.

The object is according to a second aspect achieved by a high voltage alternating current, HVAC, cable comprising a first armor type made of a first material, a second armor type made of a second material, and a joint interconnecting the first and second armor types.

In an embodiment, the high voltage alternating current, HVAC, cable comprises a first joint sleeve to which the first armor type is fastened and a second joint sleeve to which the second armor type is fastened.

In a variation of the above embodiment, the first and second joint sleeves each comprises at least one fitting device for receiving at least one cable electrically interconnecting the first armor type with the second armor type.

In an embodiment, the first material comprises galvanized steel and the second material comprises Stainless steel.

Further features and advantages of the present disclosure will become clear upon reading the following description and the accompanying drawings. 10 15 20 25 Brief description of the drawings Figure 1 illustrates schematically a HVAC cable according to an embodiment of the present invention.

Figure 2 illustrates schematically an end of the HVAC cable illustrated in figure 1.

Figure 3 illustrates schematically a joint of an HVAC cable according to an embodiment of the present invention.

Figure 4 illustrates schematically an electrical connection of an HVAC cable according to an embodiment of the present invention.

Figure 5 illustrates a flow chart over steps of a manufacturing method in accordance with an aspect the present disclosure.

Detailed description In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques, etc. in order to provide a thorough understanding. In other instances, detailed descriptions of well-known devices, circuits, cable layers and manufacturing steps and methods are omitted so as not to obscure the description with unnecessary detail. Same reference numerals refer to same or similar elements throughout the description.

As mentioned in the background section, the HVAC cable may experience high heat losses at certain locations. In order to address this problem, the inventor of the present invention has realized that it may, in some instances, be beneficial to change armor from one type to another type of a HVAC cable. For example, it may be advantageous to replace a galvanized steel armor for a stainless steel armor along a length of the cable at which length the thermal surroundings for the HVAC cable are less favorable, for example hot spots. To use an armor of stainless steel along the entire length of the HVAC cable would obviously be very good from a thermal point of view, since the stainless steel is not heated up, but such solution would not be feasible from a cost perspective.

If trying to simply replace the armor on a specific part of the HVAC cable difficulties may be encountered, such as for example corrosion problems: if joining two different 10 15 20 25 30 types of metal in direct connection there is a risk that the less noble material of the two types of metal is damaged due to corrosion. Another aspect is loss of ground connection provided by the armor.

Briefly, the above problems are addressed and a method for manufacturing a HVAC cable is provided, comprising changing part of the armor of the HVAC cable without risk for corrosion and while ensuring electrical connection along the armor. An HVAC cable having an armor of a different material along a part thereof is also provided.

Figure 1 illustrates schematically a part of a HVAC cable 1 according to an embodiment of the present invention. The HVAC cable 1 comprises a three-core cable comprising three insulated conductors for transfer of three phase electric power, one conductor core for each phase of a three-phase system. It is however noted that the present invention is applicable also for single-core HVAC cables. The conductor core part of the HVAC cable 1 is encircled and indicated by reference numeral 2.

The HVAC cable 1 comprises an inventive joint 10 for changing material of the armor along a part of the HVAC cable 1. The HVAC cable 1 thus comprises a first armor 4 made of a first material, e.g. galvanized steel (it is noted that other material may be used as well), and which is to be replaced with a second armor 3 made of a second material, e.g. stainless steel. The second armor 3 may be provided along a part of the HVAC cable 1, e.g. for installation in thermally non-optimal places. Two joints 10 are needed for such replacement, one joint when changing the armor from the first material to the second material and then another joint when changing the armor from the second material back to the first material. As mentioned earlier, armor of stainless steel is advantageous in that it is metallic material that does not heat up and is therefore suitable for use in thermally difficult places, e.g. wherein cooling is difficult. By using such second material only during a length of the HVAC cable 1 the cable is rendered much more cost-efficient than should the entire armor be made of e.g. stainless steel.

In order to change type of armor, in particular change material of the armor layer of the HVAC cable 1, a first armor 4 of a first material is welded to a first joint sleeve 7.

The first joint sleeve 7 is made of the same material as the first armor 4, and may for example comprise galvanized steel. A second armor 3 of a second material is correspondingly welded to a second joint sleeve 6. The second joint sleeve 6 is made 10 15 20 25 30 of the same material as the second armor 3, and may for example comprise stainless steel. Between these two joint sleeves 6, 7 there is a gap G. This gap G should have a length of at least one armor laying length/ pitch. The gap G is restored by using a non- metallic armor part 5. An example of a material of the non-metallic armor part 5 comprises glass fiber reinforced plastic (GRP), although other material may alternatively be used. The non-metallic armor part 5 does not conduct current, and does consequently not incur magnetic fields and is not heated up. Further, by introducing the non-metallic armor part 5 corrosion problems that could be encountered if trying to join the first (metal) armor 4 with the second (metal) armor 3 are avoided.

The joint 10 thus comprises a first joint sleeve 7, a second joint sleeve 6 and a non- metallic armor part 5. The distance between the first joint sleeve 7 and the second joint sleeve 6 is longer than the length of the non-metallic armor part 5, since the rods of the first armor 4 extend on both sides of the first joint sleeve 7. Likewise, the rods of the second armor 3 extend on both sides of the second joint sleeve 6.

The above process of replacing an armor of a first material with an armor of a second material along a part of the HVAC cable 1 is performed during manufacturing of the HVAC cable 1, and in particular when providing the HVAC cable 1 with the armor layer.

Figure 2 illustrates schematically a partly cut-through end of the HVAC cable 1 illustrated in figure 1. The HVAC cable 1 comprises the mentioned conductor cores (one such conductor core indicated at reference numeral 12 in figure 2), and may include a fiber cable 11 for transfer of signals. One or more fill-profiles 8 are provided to fill cavities created between the twisted conductor cores of the HVAC cable 1. The fill-profile 8 thereby e.g. prevents the armor layer from bending at such cavities created between the conductor cores. The first joint sleeve 7 comprises at least one fitting device 9 for providing an electrical path from the first armor 4 to the second armor 3. This is described more in detail with reference to figure 3. The HVAC cable 1 may comprise yet additional layers and/ or devices conventionally provided, e.g. tapes (indicated at reference numeral 8) for protection purposes.

Figure 3 illustrates schematically a joint sleeve 7 of an HVAC cable 1 according to an embodiment of the present invention. As mentioned earlier, the non-metallic armor 10 15 20 25 30 part 5 is not electrically conductive, and since the armor layer of the HVAC cable 1 should provide ground connection an electrical connection between the first armor 4 and the second armor 3 is provided in the form of one or more cables 14. The cable 14 is chosen such as to be able to transfer and handle the maximum allowed current that can appear in the armor 3, 4. This cable 14 may be provided in the fill-profile 8, which may be adapted for reception thereof e.g. by being provided with a groove or channel into which the cable 14 fits. The joint sleeves 6, 7 are provided with a respective fitting device 9 (only one end illustrated in figure 3) for receiving a respective end of the cable 14. Several such fitting devices 9 may be provided on the joint sleeves 6, 7 for accommodating several such cables 14.

Figure 3 also illustrates a single armor rod 15. The armor rod 15 is made of the first material and is attached, preferably welded, to the first joint sleeve 7 (as well as all other rods of the armor layer). The armor rod 15 is made of the first material on both sides of the first joint sleeve 7, before being replaced by the material of the non- metallic armor part 5.

Figure 4 illustrates schematically an electrical connection of an HVAC cable 1 according to an embodiment of the present invention. Figure 4 illustrates an aspect of the invention, omitting the conductor core etc. of the HVAC cable 1 for clearly illustrating the joint 10. As illustrated, the first joint sleeve 7 comprises two fitting devices 9a, 9b. The second joint sleeve 6 comprises correspondingly also two such fitting devices 9c, 9d. Two cables 14a, 14b are thus provided between the fitting devices 9a, 9b, 9c, 9d of the two joint sleeves 6, 7 for providing an electrical path between the first armor 4 and the second armor 3. A single armor rod 15 is also illustrated.

Figure 5 illustrates a flow chart over steps of a method 20 in accordance with an aspect the present disclosure. The method 20 for providing an armor layer of a high voltage alternating current, HVAC, cable 1 comprises providing 21 the HVAC cable 1 with a first armor type 4 made of a first material. This first armor type may be provided using a conventional machine for wrapping armor on HVAC cables.

The method 20 comprises providing 22 the HVAC cable 1 with a second armor type 3 made of a second material, at a distance, G, from the first armor type 4. This may 10 15 again be performed by using the conventional machine for such wrapping of armor on HVAC cables.

The method 20 comprises providing 23 a joint 10 interconnecting the first armor type 4 with the second armor type 3, the joint 10 comprising a non-metallic armor part 5.

In an embodiment, the providing 23 of the joint 10 comprises attaching, in particular welding, the first armor type 4 to a first joint sleeve 7 and attaching, in particular welding, the second armor type 3 to a second joint sleeve 6. The providing 23 further comprises providing the HVAC cable 1 with the non-metallic armor 5 along a distance G between the first and second armor types 4, 3. The distance G is smaller than the distance between the first and second joint sleeves 7, 6.

In an embodiment, the method 20 comprises electrically interconnecting the first armor type 4 with the second armor type 3 by means of a cable 14.

The invention has mainly been described herein with reference to a few embodiments. However, as is appreciated by a person skilled in the art, other embodiments than the particular ones disclosed herein are equally possible within the scope of the invention, as defined by the appended patent claims.

Claims (8)

10 15 20 25 Claims

1. A method (20) for providing an armor layer to a high voltage alternating current, HVAC, cable (1), the method (20) comprising: - providing (21) the HVAC cable (1) with a first armor type (4) made of a first material, - providing (22) the HVAC cable (1) with a second armor type (3) made of a second material, at a distance, G, from the first armor (4), and - providing (23) a joint (10) interconnecting the first armor type (4) with the second armor type (3), the joint (10) comprising a non-metallic armor part (5).

2. The method (20) as claimed in claim 1, wherein the providing (23) of a joint (10) comprises: - attaching the first armor type (4) to a first joint sleeve (7) and the second armor type (3) to a second joint sleeve (6), - providing the HVAC cable (1) with a non-metallic armor (5) along the distance G between the first and second armors types (4, 3).

3. The method (20) as claimed in claim 2, wherein the attaching comprises welding the first and second armor types (4, 3) to the first and second joint sleeves (7, 6), respectively.

4. The method (20) as claimed in any of the preceding claims, comprising electrically interconnecting the first armor type (4) with the second armor type (3) by means of a cable (14).

5. A high voltage alternating current, HVAC, cable (1) comprising: - a first armor type (4) made of a first material, - a second armor type (3) made of a second material, and - a joint (10) interconnecting the first and second armor types (4, 3). 10

6. The high voltage alternating current, HVAC, cable (1) as claimed in claim 5, comprising a first joint sleeve (7) to which the first armor type (4) is fastened and a second joint sleeve (6) to which the second armor type (3) is fastened.

7. The high voltage alternating current, HVAC, cable (1) as claimed in claim 6, wherein the first and second joint sleeves (7, 6) each comprises at least one fitting device (9) for receiving at least one cable (14) electrically interconnecting the first armor type (4) with the second armor type (3).

8. The high voltage alternating current, HVAC, cable (1) as claimed in any of claim 5- 7, wherein the first material comprises galvanized steel and the second material comprises stainless steel.