Self-supporting Power Cable with Segmented Conductors

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Solution Overview

Problem

Existing electric power cables for offshore installations face challenges in flexibility and fatigue resistance due to wave movements, leading to potential early cable failure when subjected to tension and movement.

Innovation Solution

A self-supporting electric power cable design featuring individual wires in a first lay direction and a supporting cord with synthetic or mineral fibers in an opposite lay direction, where the supporting cord takes primary tension, reducing stress on the wires and enhancing flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the conductor itself acts as the supporting element in a self-supporting electric power cable, then the cable can support its own weight and external forces, but the conductor is subjected to substantial tension which may lead to early fatigue failure and reduced flexibility

Engineering Contradiction:
Improvesupporting capabilityVSAvoidfatigue resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The cable structure is segmented into distinct functional components: the conductor (for electrical function) and the supporting cord (for mechanical support). This segmentation allows each component to perform its primary function without being overloaded, with the supporting cord taking the majority of tensile loads to prevent conductor fatigue

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cable employs a composite structure combining conductor materials (copper or aluminum) with supporting cord materials (synthetic fibers like aramid or polyethylene). This composite design leverages the electrical conductivity of metal conductors while using high-strength synthetic fibers for mechanical support, optimizing both electrical and mechanical performance

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If the cable is designed to be flexible for handling and installation, then the cable can be bent and positioned easily, but the flexibility may reduce the cable's ability to withstand tension and external forces

Engineering Contradiction:
ImproveflexibilityVSAvoidtension resistance
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The cable is divided into flexible conductor segments and a separate supporting cord structure. This segmentation allows the conductor to remain flexible for handling while the supporting cord provides the necessary tensile strength, with the supporting cord bearing the majority of mechanical loads

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The combination of flexible conductor materials with high-strength supporting cord materials creates a composite cable that exhibits both flexibility and tension resistance. The synthetic fiber supporting cord provides strength without compromising the overall flexibility of the cable structure

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If the cable is subjected to repeated wave-induced movements in offshore environments, then the cable must remain flexible to accommodate movement, but repeated stress cycles can lead to early fatigue failure

Engineering Contradiction:
Improvemovement accommodationVSAvoidservice life
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The cable structure separates the movement-accommodating conductor from the load-bearing supporting cord. This allows the cable to flex and accommodate wave-induced movements while the supporting cord maintains structural integrity and resists fatigue from repeated stress cycles

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The composite structure of conductor and supporting cord materials provides both movement flexibility and fatigue resistance. The synthetic fiber supporting cord has high fatigue resistance properties that protect the cable from failure due to repeated wave-induced stress cycles in offshore environments

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3443565B1Self-supporting electric power cable and buoy arrangement
Publication Date: 2021.12.22 NKT CABLES GRP
  • EP3443565B1 patent drawingFigure 1A~1B
  • EP3443565B1 patent drawingFigure 2~4C

AI summary

Herein a self-supporting electric power cable (2) is disclosed. The electric power cable comprises an outer jacket portion (6) and a core portion (8). The core portion (8) comprises at least one insulated conductor (10) and at least one supporting cord (12). The at least one insulated conductor (10) comprises a number of individual wires (14), and the at least one supporting cord (12) comprises synthetic fibres (16). The number of individual wires (14), individually or arranged in bundles (18), are arranged in a first lay direction. The at least one insulated conductor (10) and the at least one supporting cord (12) are arranged in a second lay direction. The at least one supporting cord (12) is arranged as a separate unit in a cross sectional sector of the self-supporting electric power cable (2). Thus flexible and durable power cable for sea use is provided. Also an offshore arrangement is disclosed herein.