SE1600089A1

SE1600089A1 - Rigid joint system for a submarine power cable and a three-core submarine power cable

Info

Publication number: SE1600089A1
Application number: SE1600089A
Authority: SE
Inventors: Johan Hedlund
Original assignee: Abb Technology Ltd
Priority date: 2016-03-11
Filing date: 2016-03-11
Publication date: 2016-03-15

Description

15 20 25 SUMMARY In view of the above, an object of the present disclosure is to provide a rigid joint system which is capable to withstand large bending forces associated with deep-water installations.

Hence, according to a ?rst aspect of the present disclosure there is provided a rigid joint system for a three-core submarine power cable, wherein the rigid joint system comprises: a ?rst casing for jointing two ?rst core sections of a three-core submarine power cable, a second casing for jointing two second core sections of a three-core submarine power cable, a third casing for jointing two third core sections of a three-core submarine power cable, a ?rst bend restricting device arranged to connect the ?rst casing to the second casing, and a second bend restricting device arranged to connect the second casing to the third casing.

Hence, each of the first casing, the second casing and the third casing may be made shorter in longitudinal extension than in prior art where three core joints were provided inside a very long rigid joint. This design of shorter longitudinal extension reduces the bending forces acting on the casings when lowered subsea, in particular as their orientation change from essentially horizontal to essentially vertical. Furthermore, the bend restricting devices provide bending ?exibility between the casings while limiting the possible bending between the casings.

One embodiment comprises a ?rst end bend restricting device for connection at an opposite end of the ?rst casing relative to that end of the ?rst casing to which the ?rst bend restricting device is connected.

One embodiment comprises a second end bend restricting device for connection at an opposite end of the third casing relative to that end of the third casing to which the second bend restricting device is connected.

According to one embodiment each of the ?rst casing, the second casing and the third casing is a rigid joint. 10 15 20 25 According to a second aspect of the present disclosure there is provided a three-core submarine power cable comprising two ?rst core sections, two second core sections, two third core sections, and a rigid joint system according to the ?rst aspect, wherein the ?rst casing joints the two ?rst core sections, the second casing joints the two second core sections, and the third casing joints the two third core sections.

According to one embodiment the submarine power cable is a high voltage power cable.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly de?ned otherwise herein. All references to "a/ an/ the element, apparatus, component, means, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, etc., unless explicitly stated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS The speci?c embodiments of the inventive concept will now be described, by way of example, with reference to the accompanying drawings, in which: F ig. 1 is a schematic view of an example of a rigid joint system; and Fig. 2 is a schematic perspective view of the rigid joint system in Fig. 1 in use.

DETAILED DESCRIPTION The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art.

Like numbers refer to like elements throughout the description. 10 15 20 25 30 The rigid joint system disclosed herein is especially suitable for jointing two multi-core submarine power cables. With the term “core” is here meant a segmented or solid electrical conductor provided with an electrical insulation system forming an electrical phase. In a multi-core submarine power cable, the cores are typically twinned along the length of the submarine power cable. Moreover, the submarine power cable may be provided with one or more armouring layer in the form of e.g. helically arranged wires arranged around all of the cores.

Fig. 1 shows an example of a rigid joint system 1 for a three-phase or three- core submarine power cable. The rigid joint system 1 comprises a ?rst casing 3a, a second casing 3b, and a third casing 3c. The ?rst casing 3a, the second casing 3b and the third casing 3c are made of a non-corrosive material with high mechanical withstand strength such as metal, e.g. stainless steel.

The ?rst casing 3a is arranged to joint two ?rst core sections of a submarine power cable. To this end, the ?rst casing 3a has a hollow structure for receiving a submarine power cable and to allow the submarine power cable to extend through it. The second casing 3b is arranged to joint two second core sections of a submarine power cable. The second casing 3b has a hollow structure for receiving a submarine power cable and to allow the submarine power cable to extend through it. The third casing 3c is arranged to joint two third core sections of a submarine power cable. The third casing 3c has a hollow structure for receiving a submarine power cable and to allow the submarine power cable to extend through it.

Generally, in an assembled state, each casing 3a, 3b, 3c contains only one core joint. Their longitudinal extension as well as thickness can in this manner be minimised, resulting in better performance when subjected to e.g. bending forces when lowered into sea from the cable laying vessel.

In a mounted state, the ?rst casing 3a, the second casing 3b and the third casing 3c are axially displaced relative to each other along the longitudinal extension of the jointed submarine power cable. 10 15 20 25 The rigid joint system 1 furthermore comprises a ?rst bend restricting device 5a and a second bend restricting device 5b. The ?rst bend restricting device 5a is arranged between the ?rst casing 3a and the second casing 3b, in particular connecting these two casings 3a, 3b. The second bend restricting device 5b is arranged between the second casing 3b and the third casing 3c, in particular connecting these two casings 3b, 3c.

The rigid joint system 1 also comprises a ?rst end bend restricting device 7a and a second end bend restricting device 7b. The ?rst end bend restricting device 7a is arranged to be connected to the opposite short end of the ?rst casing 3a, relative to that end which is connected to the ?rst bend restricting device 5a. The second end bend restricting device 7b is arranged to be connected to the opposite short end of the third casing 3c, relative to that end which is connected to the second bend restricting device 5b.

Each bend restricting device 5a-5b, 7a-7b may for example be one of a bend restrictor or a bend stiffener.

Fig. 2 shows a three-core submarine power cable 9 comprising the rigid joint system 1. The exempli?ed three-core submarine power cable has thus been jointed by means of the rigid joint system 1. Here, each core joint is symbolically illustrated by a respective reference J 1-J 3. Hereto, in the example in Fig. 2, the three-core submarine power cable 9 has two ?rst core sections jointed inside the ?rst casing 3a, two second core sections jointed inside the second casing 3b, and two third core sections jointed inside the third casing 3c.

In Fig. 2, it can furthermore be seen that the shorter length of the casings 3a- 3c and the ?exibility provided between them by means of the bend restricting devices 5a, 5b reduces the bending forces acting on the casings 3a-3c which are rigid. In contrast, in the prior art, the length of the rigid joint would essentially correspond to the total length of the three casings 3a-3c, which leads to higher force in?uence on the body of the rigid joint. 10 15 The rigid joint system and three-core submarine power cable presented herein may for example be utilised in subsea applications such as subsea power transmission or subsea power distribution. The rigid joint system and the submarine power cable comprising the same are especially suitable for installation at ultra deep-water, although they could also be used at smaller depths.

It should also be noted that the submarine power cable could as an alternative to having exactly three-cores have more than three cores, i.e. it can in general be a multi-core submarine power cable with three or more cores. Thus, the rigid joint system should have the corresponding number of casings, i.e. one for each core.

The inventive concept has mainly been described above with reference to a few examples. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as de?ned by the appended claims.

Claims

10 15 20 25 CLAIMS

1. A rigid joint system (1) for a three-core submarine power cable (9), wherein the rigid joint system (1) comprises: a ?rst casing (3a) for jointing two ?rst core sections of a three-core submarine power cable (9), a second casing (3b) for jointing two second core sections of a three-core submarine power cable (9), a third casing (3c) for jointing two third core sections of a three-core submarine power cable (9), a ?rst bend restricting device (5a) arranged to connect the ?rst casing (3a) to the second casing (3b), and a second bend restricting device (5b) arranged to connect the second casing (3b) to the third casing (3c).

2. The rigid joint system (1) as claimed in claim 1, comprising a ?rst end bend restricting device (7a) for connection at an opposite end of the ?rst casing (3a) relative to that end of the ?rst casing (3a) to which the ?rst bend restricting device (5a) is connected.

3. The rigid joint system (1) as claimed in claim 1 or 2, comprising a second end bend restricting device (7b) for connection at an opposite end of the third casing (3b) relative to that end of the third casing (3b) to which the second bend restricting device (5b) is connected.

4. The rigid joint system (1) as claimed in any of the preceding claims, wherein each of the ?rst casing (3a), the second casing (3b) and the third casing (3c) is a rigid joint.

5. A three-core submarine power cable (9) comprising: two ?rst core sections, two second core sections, two third core sections, and a rigid joint system (1) as claimed in any of claims 1-4, wherein the ?rst casing (3a) joints the two ?rst core sections, the second casing (3b) joints the two second core sections, and the third casing (3c) joints the two third core sections.

6. The three-core submarine power cable (9) as claimed in claim 5, wherein the three-core submarine power cable is a high voltage power cable.