SE1400049A1 - Subsea power cable - Google Patents

Abstract

Föreliggande uppfinning avser en undervattenskraftkabel () som innefattar en ledande kärna (il), ett elektriskt isolationssystem () anordnat att elekt-risk isolera den ledande kärnan (), ett armeringslager (a,b,c,d) inne-fattande ett flertal vajrar, vilket armeringslager (a,b,c,d) är anordnat att skydda den ledande kärnan () och det elektriska isolationssystemet (), och en yttre mantel () anordnad att omgärda armeringslagret (a,b,c,d). Undervattenskraftkabeln () har vidare ett mellanliggande lager () anordnat mellan armeringslagret (a,b,c,d) och den yttre manteln (), vilket mellanliggande lager () är anpassat att förhindra deformation av vajrarna då undervattenskraftkabeln () pressas samman.(Fig. 1)

Description

10 15 20 25 load, resulting in bird caging of the wires. This is when the armour wires are expanding due to axial compression to form what looks like a bird cage.

SUMMARY Analysis shows that allowing a small amount of compression in subsea power cables will expand the weather window significantly with considerable cost saving as a result.

In view of the above, a general object of the present disclosure is to provide a subsea power cable that is able to handle axial compression load.

Hence, according to a first aspect of the present disclosure there is provided a subsea power cable comprising: a conductive core, an electrical insulation system arranged to electrically insulate the conductive core, an armour wire layer comprising a plurality of vvires, the armour wire layer being arranged to protect the conductive core and the electrical insulation system, an external sheath arranged to enclose the armour wire layer, and an intermediate layer arranged between the armour wire layer and the external sheath, the inter- mediate layer being adapted to prevent bird caging of the wires of the armour wire layer in the case of compression of the subsea power cable.

According to one embodiment the intermediate layer is a tape layer.

According to one embodiment the intermediate layer has a tensile strength in the range of 5 kN to 60 kN.

One embodiment comprises a plurality of armour wire layers each compris- ing a plurality of wires, and wherein the intermediate layer is arranged be- tween the outermost of the armour wire layers and the external sheath.

According to one embodiment the subsea power cable is an AC power cable or a DC power cable.

According to one embodiment the subsea power cable is a dynamic subsea power cable or a static subsea power cable. 10 15 20 25 According to one embodiment the outer diameter of the subsea power cable is in the range 50 mm to 250 mm.

According to one embodiment the subsea 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 deflned 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 other- wise.

BRIEF DESCRIPTION OF THE DRAWINGS The specific embodiments of the inventive concept will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 depicts a perspective view of a portion of a subsea power cable with several layers partially cut away to expose the interior of the subsea power cable.

DETAILED DESCRIPTION The inventive concept will now be described more fully hereinafter with ref- erence to the accompanying drawings, in which exemplifying embodiments are shown. The inventive concept may, however, be embodied in many differ- ent 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.

Fig. 1 depicts an example of a subsea power cable 1 with several layers partial- ly cut away to expose the interior of the subsea power cable 1. The subsea power cable 1 may be a dynamic cable or a static cable. Furthermore, alt- hough an alternating current (AC) cable is shown, the subsea power cable 10 15 20 25 could alternatively be a direct current (DC) cable. The subsea power cable may for example be a high voltage cable or a medium voltage cable.

The subsea power cable 1 comprises an external sheath 3, an intermediate layer 5, at least one armour wire layer 7a, 7b, 7c, 7d, an electrical insulation system 9 and a conductive core 11.

The conductive core 11 comprises electrically conducting material such as copper, and may comprise one ore more conductors insulated from each oth- er, depending on the number of electrical phases the subsea power cable is designed to handle. The conductive core 11 is surrounded by the electrical insulation system 9 for electrically insulating the conductive core 11 from the at least one armour wire 7a-7d and the external sheath 3. The electrical insu- lation system 9 may for example comprise cross-linked polyethylene.

The electrical insulation system 9 is surrounded by one or more armour wire layers 7a-7d concentrically arranged around the electrical insulation system 9. Each armour wire layer 7a-7d comprises a plurality of wires such as metal wires for increasing the mechanical strength of the subsea power cable 1.

The outermost armour wire layer 7a, i.e. that armour wire layer closest to the external sheath 3, is surrounded by an intermediate layer 5. The intermediate layer 5 is thus arranged between the armour wire layer 7a and external sheath 3. In Variations of the subsea power cable comprising only one arrnour wire layer, the intermediate layer 5 is arranged between this armour wire layer and the external sheath 3. The intermediate layer is high-tensile and thereby adapted to prevent bird caging of the wires of the armour wire layer(s) 7a-7d.

The external sheath 3 protects the armour wire layer 7a.

The intermediate layer 5 may be a tape layer. The tape layer may be created by winding a high-tensile tape around the outermost armour wire 7a. The tensile strength of the intermediate layer may for example be in the range 5 kN to 60 kN. As mentioned above, by means of this high-tensile intermediate layer, deformation such as bird caging of the armour wire layer(s) 7a-7d may 10 be reduced or prevented. The weather window for installing the subsea power cable may thereby be expanded.

The subsea power cable may for example have an external diameter in the range 50 mm to 250.

It is envisaged that the subsea power cable presented herein can find applica- tions within the oil and gas industry for example for subsea HVDC/HVAC power transmission and power distribution systems, as well as offshore pow- er generation such as wind energy, tidal energy, wave energy, and ocean cur- rent energy.

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 defined by the appended claims.

Claims (8)

10 15 20 25 CLAIMS

1. A subsea power cable (1) comprising: a conductive core (11), an electrical insulation system (9) arranged to electrically insulate the conductive core (11), an armour wire layer (7a, 7b, 7c, 7d) comprising a plurality of wires, the armour wire layer (7a, 7b, 7c, 7d) being arranged to protect the conductive core (11) and the electrical insulation system (9), an external sheath (3) arranged to enclose the armour wire layer (7a, 7b, 70, 7d), and an intermediate layer (5) arranged between the armour wire layer (7a, 7b, 7c, 7d) and the external sheath (3), the intermediate layer (5) being adapted to prevent deformation such as bird caging of the wires of the armour wire layer (7a, 7b, 7c, 7d) in the case of compression of the subsea power cable (1).

2. The subsea power cable (1) as claimed in claim 1, wherein the intermedi- ate layer (5) is a tape layer.

3. The subsea power cable (1) as claimed in claim 1 or 2, wherein the inter- mediate layer (5) has a tensile strength in the range of 5 kN to 60 kN.

4. The subsea power cable (1) as claimed in any of the preceding claims, comprising a plurality of armour wire layers (7a, 7b, 7c, 7d), each comprising a plurality of wires, and wherein the intermediate layer (5) is arranged be- tween the outermost of the armour wire layers (7a) and the external sheath (3)-

5. The subsea power cable (1) as claimed in any of the preceding claims, wherein the subsea power cable (1) is an AC power cable or a DC power cable. 10

6. The subsea power cable (1) as claimed in any of the precedíng claims, wherein the subsea power cable (1) is a dynamic subsea power cable or a stat- ic subsea power cable.

7. The subsea power cable (1) as claimed in any of the precedíng claims, wherein the outer diameter of the subsea power cable is in the range 50 mm to 250 mm.

8. The subsea power cable (1) as claimed in any of the precedíng claims, wherein the subsea power cable is a high voltage power cable.