HVDC Power Cable Barrier Layers Against Chemical Migration
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Solution Overview
Problem
High voltage direct current (HVDC) power cables face issues with electrical DC conductivity and thermal runaway due to chemical migration from water blocking tapes into the insulation system, leading to increased dielectric losses and reduced robustness.
Innovation Solution
Incorporating inner and outer barrier layers between the water blocking materials and the insulation system to hinder the diffusion of mobile chemical substances, using materials like metallic laminates or conductor tapes to prevent substance migration and enhance electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water blocking tapes are used to prevent water infiltration, then water resistance is improved, but chemical substances migrate into the insulation increasing DC conductivity and dielectric losses
Solution Approach 1:
A conductor tape is introduced as an intermediary layer between the water blocking tape and the insulation system. This conductor tape acts as a barrier that prevents chemical substances from the water blocking tape from migrating into the insulation, while still allowing the water blocking function to operate effectively. The conductor tape is applied to surround the conductor radially outwards, positioned between the water blocking tape and the inner semi-conducting layer.
2Reliability
If water blocking materials are applied to surround the conductor, then longitudinal water blocking is achieved, but substances originate from the water blocking materials and increase DC conductivity in insulation
Solution Approach 1:
The conductor tape serves as a mediating barrier that allows the water blocking material to perform its function of preventing longitudinal water infiltration while blocking the migration path of chemical substances that would otherwise increase DC conductivity and cause dielectric losses in the insulation.
3Reliability
If metallic laminates or extruded lead sheath are provided around the insulation system, then water barrier protection is improved, but device complexity increases
Solution Approach 1:
The conductor tape is positioned to perform multiple functions simultaneously: it acts as a water barrier protection layer, a diffusion barrier preventing chemical migration from water blocking materials, and maintains the electrical field distribution. This multi-functionality reduces the need for separate dedicated layers, thereby simplifying the overall cable structure while maintaining protective functions.
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 barrier layers effectively reduce DC electrical conductivity in the insulation, improving the cable's robustness and allowing for higher voltage and temperature operation while maintaining effective water blocking.
Implementation Method 1
an inner barrier layer is arranged as a diffusion hindering layer between the inner water blocking material and the insulation system. Further, an outer barrier layer is arranged as a diffusion hindering layer between the insulation system and the outer water blocking material
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to an electric power cable (1) and to a process for the production of the cable (1) comprising a metal conductor (2) and an electric insulation system surrounding the conductor coaxially and radially outwards of the conductor having improved electric properties. The insulation system comprises an inner semi-conducting layer surrounded radially outwards by an insulation layer and wherein the insulation layer is surrounded radially outwards by an outer semi-conducting layer. The electric power cable further comprises an inner water blocking material (6) arranged in the conductor and/or to surround the conductor (2) radially outwards and an outer water blocking material (18) arranged radially outwards from the insulation system. An inner barrier layer (8) is arranged as a diffusion hindering layer between the inner water blocking material (6) and the insulation system (20) and an outer barrier layer (16) is arranged as a diffusion hindering layer between the insulation system (20) and the outer water blocking material (18).