Insulated Submarine Cable With Varying Insulation Thickness
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Solution Overview
Problem
Insulated cables used in subsea applications face limitations due to uniform manufacturing standards, leading to over-specification in certain sections, increased costs, and inefficient use, as well as environmental concerns from materials like lead, which can result in unnecessary replacement and handling challenges.
Innovation Solution
The design of insulated submarine cables with varying core cross-sectional areas and insulating material thicknesses along different lengths, optimized for specific environmental conditions, such as air and water exposure, using a water-tree retardant polymer to reduce the need for hermetic barriers and minimize material usage, and incorporating induction-brazed taper joints and filler material to maintain mechanical properties and handle stress variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform manufacturing standards are applied throughout the entire cable length, then dielectric strength requirements are met in all sections, but material usage increases and costs rise due to over-specification in less demanding sections
Solution Approach 1:
The cable is designed with varying core cross-sectional areas and insulating material thicknesses along its length, matching the specific dielectric strength requirements of different environmental sections. High-voltage sections receive thicker insulation while low-voltage sections have reduced insulation, eliminating material waste from uniform over-specification.
Solution Approach 2:
The patent implements continuous or stepped variations in core cross-sectional area and insulating material thickness along the cable length, transitioning between different manufacturing specifications to optimize material usage while maintaining adequate dielectric strength for each local environment.
2Reliability
If hermetic waterproofing materials such as lead are used to prevent water permeation, then the insulating material remains dry and dielectric strength is maintained, but cable weight increases and manoeuvrability deteriorates
Solution Approach 1:
The patent removes traditional hermetic waterproofing layers (lead, steel, pitch) entirely, accepting that water will permeate the cable structure. Instead, it relies on water-tree retardant insulating materials that maintain dielectric strength even when wet, eliminating the weight penalty of heavy waterproofing materials.
Solution Approach 2:
The patent converts the previously harmful effect of water permeation into an acceptable condition by using insulating materials specifically designed to resist water-tree formation and maintain dielectric properties in wet environments, thereby eliminating the need for heavy hermetic barriers.
3Reliability
If hermetic waterproofing materials are used, then water permeation is prevented, but the cable becomes difficult to manoeuvre and install
Solution Approach 1:
By removing rigid hermetic waterproofing layers, the cable achieves greater flexibility and ease of handling during installation and manoeuvring, while still maintaining adequate waterproofing performance through water-tree retardant materials.
4Reliability
If hermetic waterproofing materials are used, then water permeation is prevented, but the materials may fracture or disintegrate where the cable moves, compromising waterproofing properties
Solution Approach 1:
The patent eliminates rigid hermetic waterproofing materials that are prone to fracturing and disintegrating under mechanical stress, replacing them with flexible water-tree retardant insulating materials that maintain both waterproofing effectiveness and structural integrity during cable movement and installation.
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 ensures appropriate dielectric strength and reduced material usage, lowering costs and environmental impact by tailoring cable specifications to specific conditions, extending cable life and simplifying installation by avoiding over-insulation and reducing stress concentrations.
Implementation Method 1
The insulating material may be a water tree-retardant material
Implementation Method 2
The joint may be an induction-brazed taper joint
Implementation Method 3
The joint may be an induction-brazed taper joint
Implementation Method 4
An insulated cable's dielectric strength is also affected by the operating temperature of the cable, which is dependent on the cable's ability to dissipate heat
Data Source
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AI summary
The invention relates to insulated submarine cables including conductive cores (3a, 3b) and insulating material (5a, 5b) surrounding the conductive cores (3a, 3b). Such an insulated cable includes a first length and a second length. The cable has a roughly constant core (3a) cross-sectional area Al and a roughly constant insulating material (5a) thickness Tl along the first length, and a different roughly constant core (3b) cross-sectional area A3 and/or a different roughly constant insulating material (5b) thickness T2 along the second length. The cable may include one or more other lengths which join the first length and the second length to one another.