Composite Armouring Wire Structure for Submarine Cable Heat Management
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Solution Overview
Problem
Submarine electric power transmission cables face limitations in current carrying capacity due to heat generation from magnetic losses in ferromagnetic armouring materials, leading to reduced efficiency and increased costs when using larger cables or complex joint solutions.
Innovation Solution
A composite armouring wire structure is created by joining non-magnetic and magnetic steel wires with different magnetic permeabilities, coated with thick metallic protection layers, to manage heat generation differently across cable sections without disrupting cable continuity or requiring additional joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ferromagnetic steel wires are used as armouring material, then mechanical protection and tensile strength are improved, but magnetic losses increase generating heat that limits current carrying capacity
Solution Approach 1:
The armouring structure is segmented into multiple layers with different magnetic properties. The patent uses a composite armouring comprising an inner layer of ferromagnetic steel wires for mechanical strength and an outer layer of non-magnetic stainless steel wires to minimize magnetic losses. This segmentation allows each layer to perform its specific function without compromising the other.
Solution Approach 2:
The patent employs composite armouring materials combining ferromagnetic and non-magnetic properties. Specifically, it uses a combination of carbon steel wires (ferromagnetic) and stainless steel wires (non-magnetic) in a layered structure, creating a composite material system that balances mechanical protection requirements with magnetic loss reduction.
2Loss of energy
If cable size is increased to improve heat dissipation, then current carrying capacity is improved, but cable weight and cost increase
Solution Approach 1:
Instead of uniformly increasing the entire cable size, the patent applies local quality improvement by using non-magnetic stainless steel armouring specifically in sections where magnetic losses are problematic. This allows heat dissipation improvement in specific locations without proportionally increasing the overall cable weight and cost.
Solution Approach 2:
The patent changes the magnetic permeability parameter of the armouring material from ferromagnetic to non-magnetic properties in specific layers. This parameter change reduces magnetic losses and heat generation, allowing the cable to maintain higher current carrying capacity without needing to increase its physical dimensions for heat dissipation.
3Loss of energy
If non-magnetic stainless steel wires are used as armouring, then magnetic losses are reduced, but corrosion resistance may be compromised without adequate protection
Solution Approach 1:
The patent introduces an intermediary protective element - a corrosion protection coating or jacketing layer - between the non-magnetic stainless steel armouring wires and the external environment. This intermediary layer provides the necessary corrosion protection while allowing the stainless steel wires to maintain their non-magnetic properties and minimize magnetic losses.
Solution Approach 2:
The armouring system uses composite materials combining non-magnetic stainless steel wires with corrosion-resistant coating materials or protective jackets. This composite structure provides both the magnetic loss reduction benefits of stainless steel and the corrosion resistance needed for reliable long-term operation in submarine environments.
4Loss of energy
If cable sections of different sizes are used to manage heat dissipation, then current rating is improved, but cable continuity is impaired requiring transition joints
Solution Approach 1:
The patent maintains homogeneity in the cable structure by using consistent armouring construction throughout the entire cable length. Instead of creating visible sections of different sizes, the uniform non-magnetic stainless steel armouring provides consistent heat dissipation and magnetic loss reduction properties along the whole cable, eliminating the need for transition joints between different cable sections.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach maintains consistent current ratings across varying heat dissipation environments, reduces production costs, and enhances mechanical properties while minimizing magnetic losses and corrosion, thus prolonging cable lifespan.
Implementation Method 1
a first metallic material coated with a first metallic protection coating
Implementation Method 2
butt welded joints comprising resistive butt welding joints
Implementation Method 3
flash butt welding joints
Implementation Method 4
tungsten inert gas (TIG) welding joints
Implementation Method 5
the magnetic field generated by the current flowing in the conductors induces magnetic losses in ferromagnetic materials
Implementation Method 6
induces magnetic losses in ferromagnetic materials, or in a material having high magnetic permeability
Implementation Method 7
a first metallic material coated with a first metallic protection coating having a thickness more than 100 g/m2
Data Source
Figure 1~3
AI summary
An electric power transmission cable, comprising: at least a first portion provided with a plurality of first armouring wires having a first tensile strength, said plurality of first armouring wires being made of a first metallic material coated with a first metallic protection coating with a thickness more than 100 g/m2 , said first metallic material having a first magnetic permeability μ1, at least a second portion provided with a plurality of second armouring wires having a second tensile strength, said plurality of second armouring wires being made of a second metallic material coated with a second metallic protection coating with a thickness more than 100 g/m2, said second metallic material having a second magnetic permeability μ2, and μ2≠ μ1, each of said plurality of first armouring wires being longitudinally joined to one of said plurality of second armouring wires at a joint portion, said joint portion having a third tensile strength, wherein the third tensile strength is at least more than 80% of the lower tensile strength of the first tensile strength and the second tensile strength.