Subsea Power Cable Composite Conductor for Deepwater Tension

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Solution Overview

Problem

Deep water subsea power cables face issues with conductor yield under high laying tension, leading to elongation and damage to insulation, as lighter metals used to reduce weight are not sufficient to withstand the stress, causing the armour to take the tension and potentially suffer damage.

Innovation Solution

A subsea power cable design featuring multiple conductor elements made of different materials, such as copper, aluminium, and steel, distributed throughout the conductor to optimize conductivity, weight, and volume, ensuring the conductor does not yield under high tension by selecting materials with varying yield stress limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If lighter metals such as aluminium are used for the conductor to reduce weight, then the weight of the cable is reduced, but the conductor yields under high laying tension in deep water

Engineering Contradiction:
Improveweight of cableVSAvoidresistance to laying tension
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The conductor is constructed as a composite of multiple materials with different properties (copper, aluminium, steel) arranged in specific configurations. This allows the conductor to achieve an optimal balance between weight and strength, where lighter materials reduce overall cable weight while stronger materials (like steel) provide the necessary tensile strength to withstand high laying tensions without yielding.

Inventive Principle:
Principle #40Composite materials

2Strength

If the conductor yields under high tension, then the conductor is elongated and diameter is reduced, but the insulation is damaged

Engineering Contradiction:
Improveconductor strengthVSAvoidinsulation integrity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The multi-material conductor construction prevents yielding under high tension through the combined mechanical properties of different materials. By selecting materials with appropriate yield strengths and arranging them in specific configurations (stranded, layered, or composite structures), the conductor maintains its dimensional stability and radial pressure on the insulation, thereby preventing insulation damage and ensuring cable reliability during high-tension laying operations.

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If multiple conductor elements of different materials are used to optimize conductivity and weight, then the conductor properties can be adapted, but the conductor structure becomes more complex

Engineering Contradiction:
Improveconductor property optimizationVSAvoidconductor structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The conductor employs a composite structure with multiple elements of different materials (copper, aluminium, steel) arranged in systematic configurations such as stranded bundles or layered constructions. This composite approach enables independent optimization of conductivity, weight, and strength by selecting appropriate material combinations and arrangements, while the systematic structure maintains manufacturability and installation feasibility.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The conductor is divided into multiple separate elements or strands of different materials rather than using a single homogeneous material. This segmentation allows each material to contribute its specific properties (copper for conductivity, aluminium for weight reduction, steel for strength) while the overall conductor achieves a balanced performance profile suitable for deepwater cable applications.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2905788B1Subsea power cable
Publication Date: 2020.09.02 NEXANS SA
  • EP2905788B1 patent drawingFigure 1~2
  • EP2905788B1 patent drawingFigure 3~5

AI summary

A subsea power cable (1) comprising a conductor (10) surrounded by at least one layer of insulation (20) and at least one layer of armouring (40), wherein the conductor (10) comprises at least a first conductor element (12b, 15b) and a second conductor element (12a, 15a), where the first conductor element is made of a first material and the second conductor element is made of a second material and where the first and the second materials are different.