Lead-Free Cable Water Barrier Laminate for Dynamic Fatigue Resistance
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Solution Overview
Problem
Current power cable water barriers made of lead are heavy, costly, environmentally harmful, and unsuitable for dynamic applications due to low fatigue resistance, and they do not effectively conduct capacitive currents, leading to potential electrical breakdown.
Innovation Solution
A laminate structure comprising a metal foil and thermoplastic semiconducting polymer layers, thermally joined by heat treatment, forms a lightweight, conductive water barrier that encapsulates the cable core, allowing capacitive currents to be conducted radially and preventing water intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead is used as water barrier material, then reliable water protection is achieved, but cable weight increases significantly
Solution Approach 1:
The patent employs a composite laminate structure consisting of a metal foil layer (aluminum, steel, or copper) combined with a polymer layer (extruded or wrapped). This composite approach maintains the water barrier functionality while significantly reducing weight compared to solid lead construction, as the polymer component is much lighter than lead while the metal foil provides the necessary barrier properties.
Solution Approach 2:
The invention changes the material parameters by transitioning from solid lead to a layered composite structure with specific thickness combinations. The metal foil thickness and polymer layer thickness are optimized to achieve equivalent water protection performance with reduced overall density and weight, thereby resolving the contradiction between reliability and weight.
2Reliability
If lead is used as water barrier material, then water blocking is achieved, but fatigue resistance is insufficient for dynamic cables
Solution Approach 1:
The laminate structure combines a ductile metal foil layer with a flexible polymer layer, creating a composite material that exhibits superior fatigue resistance compared to solid lead. The polymer layer accommodates dynamic movements and stress cycles, while the metal foil maintains the water barrier integrity, making the water barrier suitable for dynamic submarine power cables.
3Reliability
If lead is used as water barrier material, then water protection is provided, but environmental harm increases
Solution Approach 1:
The invention extracts and removes lead from the water barrier composition entirely, replacing it with environmentally benign materials such as aluminum, steel, copper foils and polymer layers. This elimination of toxic lead material while preserving water protection functionality directly addresses the environmental harm issue.
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 laminate structure provides a durable, environmentally friendly water barrier with low electrical resistance and excellent water-blocking properties, reducing weight and operational costs while preventing electrical breakdown.
Implementation Method 1
the laminate structure is thermally joined by a heat treatment
Implementation Method 2
capacitive currents to be conducted radially out of the cable
Data Source
Figure 1a~1c
Figure 2a
Figure 2b
AI summary
The present invention relates to a lead-free water barrier suited for dynamical submarine high voltage power cables wherein the water barrier comprises a laminate structure, and wherein the laminate structure comprises a metal foil having a lower and an upper surface area, a first layer of a thermoplastic semiconducting polymer laid onto the first adhesive layer, and a second layer of a thermoplastic semiconducting polymer laid onto the second adhesive layer, and wherein the laminate structure is thermally joined by a heat treatment.