Metallic Sheath Joint for Lead-Free Watertight Power Cables
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The transition from lead to lead-free materials in power cables complicates the manufacturing process due to increased difficulty in handling and requires innovative solutions for radial water protection, especially in submarine power cables.
Innovation Solution
A power cable design featuring a metallic water blocking layer with a lead-free metal material having lower yield strength, which is thermally joined along its perimeter to form a watertight connection between axial sections, allowing for malleability and ease of restoration, and utilizing materials like tin, brass, or indium to reduce galvanic corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free metal material is used in the metallic water blocking layer, then health and environmental safety is improved, but handling difficulty and manufacturing complexity increase
Solution Approach 1:
The patent changes the material parameter by selecting lead-free metals (tin, zinc, aluminum, or their alloys) with specific properties: lower yield strength (≤450 MPa) and lower melting temperature compared to traditional lead. This parameter change enables thermal joining processes that simplify manufacturing while maintaining safety benefits.
Solution Approach 2:
The patent replaces mechanical joining methods with thermal joining processes. The metallic water blocking layer sections are joined by thermal contact along their entire inner or outer perimeter, leveraging the lower melting temperature of lead-free materials to achieve reliable connections without complex mechanical fastening systems.
2Ease of repair
If lead-free metal material with lower yield strength is used, then malleability and restorability are improved, but structural strength decreases
Solution Approach 1:
The patent specifies yield strength parameters (≤450 MPa, preferably ≤250 MPa, most preferably ≤200 MPa) and melting temperature parameters that optimize the balance between malleability for restoration and sufficient structural strength for water blocking functionality.
Solution Approach 2:
The patent introduces thermal energy as an intermediary to join the metallic sections. By heating the contact surfaces to facilitate thermal bonding, the process achieves strong joints without requiring high mechanical forces during assembly, thus protecting the softer lead-free material while ensuring structural integrity.
3Reliability
If different metal materials are used in different axial sections, then galvanic corrosion resistance is improved, but material compatibility and manufacturing complexity increase
Solution Approach 1:
The patent applies different metal materials to different axial sections of the metallic water blocking layer based on local requirements. This allows optimization of each section's properties while managing galvanic corrosion through controlled material transitions at joints.
Solution Approach 2:
The thermal joining process acts as an intermediary that creates metallurgical bonds between different metal materials. This thermal bonding method ensures compatibility between dissimilar metals by creating diffusion bonds that reduce galvanic effects compared to mechanical connections.
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 design enhances the handling and restoration of the metallic water blocking layer, ensuring a watertight connection and reducing galvanic corrosion, thus addressing the challenges posed by lead-free materials in power cable manufacturing.
Implementation Method 1
the intermediate axial section is joined thermally along its entire inner or outer perimeter with each of the first axial section and the second axial section to obtain a watertight connection
Data Source
Figure 1~3A
Figure 3B~4
AI summary
A power cable comprising: a conductor, an insulation system comprising an inner semiconducting layer arranged around the conductor, an insulation layer arranged around the inner semiconducting layer, and an outer semiconducting layer arranged around the insulation layer, a metallic water blocking layer (13) arranged around the insulation system (5), comprising a first axial section (13a), a second axial section (13b), and an intermediate axial section (13c) made of a lead-free metal material which is different from a first metal material of at least one of the first axial section (13a) and the second axial section (13b), the intermediate axial section (13c) being arranged between the first axial section (13a) and the second axial section (13b), wherein the intermediate axial section (13c) is joined thermally along its entire inner or outer perimeter with each of the first axial section (13a) and the second axial section (13b) to obtain a watertight connection between the intermediate axial section (13c) and each of the first axial section (13a) and the second axial section (13b), wherein the lead-free metal material has a lower yield strength than the first metal material.