Marine Cable Wire Dual-Layer Insulation Design
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Solution Overview
Problem
Marine and sub-sea cables face challenges due to corrosive and conductive seawater, mechanical stresses, and limitations in diameter, temperature range, and physical toughness, leading to large diameters and restricted length storage.
Innovation Solution
A primary wire design featuring a conductive core with an inner layer of radiation-crosslinked polyalkene and an outer layer of radiation-crosslinked polyvinylidene fluoride, providing enhanced insulation, mechanical properties, and corrosion resistance, allowing for a thinner and lighter cable with improved temperature range and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick walled XLPE primary wire is used to provide necessary electrical resistance and temperature rating, then electrical insulation and temperature range are improved, but cable diameter increases and flexibility deteriorates
Solution Approach 1:
The patent applies composite materials by combining two different insulating materials: XLPE (cross-linked polyethylene) for the inner layer providing electrical insulation, and PTFE (polytetrafluoroethylene) for the outer layer providing flexibility and chemical resistance. This composite structure allows the cable to achieve both high reliability electrical properties and improved flexibility with reduced diameter compared to conventional single-material thick-walled XLPE wires.
2Reliability
If thick walled XLPE primary wire is used to ensure electrical resistance, then electrical insulation is improved, but cable weight increases
Solution Approach 1:
The composite structure of inner XLPE layer and outer PTFE layer provides the necessary electrical resistance with reduced material thickness. PTFE has excellent electrical insulating properties with lower density than XLPE, allowing the outer layer to contribute to insulation while reducing overall cable weight. The synergistic combination maintains electrical performance while achieving weight reduction.
3Reliability
If conventional XLPE wire design is used to provide electrical insulation, then electrical resistance is improved, but temperature range and physical toughness are limited
Solution Approach 1:
The patent uses composite materials where XLPE provides electrical resistance in the inner layer, while the outer PTFE layer contributes high temperature resistance (-55°C to +150°C range) and physical toughness. PTFE's inherent properties include excellent low-temperature flexibility and high-temperature stability, along with resistance to chemical attack from seawater. This composite approach enables the cable to operate across a wide temperature range with enhanced physical toughness while maintaining electrical resistance.
4Strength
If conventional cable design is used to ensure mechanical strength, then strength is improved, but cable diameter increases limiting storage length
Solution Approach 1:
The composite structure of inner XLPE and outer PTFE layers provides enhanced mechanical strength through material synergies. PTFE offers superior abrasion resistance and tensile strength compared to conventional single-material designs. The optimized wall thickness distribution in the composite structure achieves necessary mechanical strength with reduced overall diameter, allowing longer cable lengths to be stored on standard drums.
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
The solution results in cables that are tougher, more flexible, and resistant to chemical attacks, with higher temperature ranges and electrical insulation, enabling longer cable lengths on a single drum and improved performance in marine and sub-sea applications.
Implementation Method 1
both layers are radiation-cross linked. The radiation crosslinking of the insulating polymers imparts increased resistance to cold flow and renders them non-melting at high temperature.
Data Source
AI summary
Primary wire for marine or undersea cable comprises a conducting core (10), typically a multifilament core of copper, and an insulating sheath comprising an insulating inner layer (12) having a thickness of 0.35 to 1.0mm, preferably 0.5 to 0.75mm, and an outer protective layer (14) of polyvinylidene fluoride having a thickness of 0.15 to 0.3mm, at least the outer layer being radiation crosslinked. The inner and outer layers are preferably crosslinked together using electron beam radiation. The combination of the inner and outer layers of the sheath enables marine and subsea cables and the like to be made with smaller diameters, without loss of capacity or electrical properties and with an increase in overall performance such as temperature range and mechanical properties.