Water Blocking Electric Cable Inner Semiconductive Layer
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Solution Overview
Problem
Water penetration issues at the interface between the conductor and the inner semiconductive layer in high-voltage and special high-voltage submarine cables, leading to adhesion problems and degradation of electrical performance due to heat exposure, especially under deep-sea pressures.
Innovation Solution
A water blocking power cable design featuring a watertight conductor with an inner semiconductive layer composed of a mixture of polyolefin-based rubber or resin, carbon black, and aliphatic alkyl peroxide, crosslinked by heating, and an insulating layer formed from polyolefin-based materials, with all layers extruded simultaneously to ensure smooth interfaces and enhanced adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conductive material mainly comprising carbon black and butyl rubber is used as the inner semiconductive layer to improve adhesion with the conductor, then adhesion property is improved, but the interface between the inner semiconductive layer and the insulating layer becomes rough due to different fluidity
Solution Approach 1:
The patent changes the chemical composition parameters of the inner semiconductive layer by incorporating peroxide and sulfur compounds, which modify the material's fluidity and adhesion characteristics simultaneously, resolving the contradiction between adhesion and interface smoothness
Solution Approach 2:
The patent uses a composite material formulation for the inner semiconductive layer that combines carbon black, butyl rubber, peroxide, and sulfur compounds, creating a material that achieves both good adhesion to the conductor and compatible fluidity with the insulating layer for a smooth interface
2Manufacturing precision
If the inner semiconductive layer is extruded simultaneously with the insulating layer in one crosshead to improve interface smoothness, then interface smoothness is improved, but water penetration occurs at the interface under deep-sea pressure
Solution Approach 1:
The patent modifies the chemical composition of the inner semiconductive layer by adding peroxide and sulfur compounds, which create a more robust material structure that resists water penetration while maintaining interface smoothness during simultaneous extrusion
Solution Approach 2:
The patent uses readily available peroxide and sulfur compounds as additives that provide temporary chemical protection during the extrusion process, forming a stable interface structure that prevents water penetration under deep-sea conditions
3Reliability
If carbon black and butyl rubber are used as watertight material to block water penetration, then water blocking performance is improved, but adhesion to the conductor deteriorates
Solution Approach 1:
The patent creates a composite material system for the inner semiconductive layer that combines carbon black, butyl rubber, peroxide, and sulfur compounds, where the peroxide and sulfur components enhance adhesion to the conductor while the carbon black and butyl rubber maintain water blocking performance
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
Effectively blocks water penetration at the interface, maintaining adhesion and electrical performance, allowing for early recovery of damaged sections by preventing water ingress and ensuring reliable operation under high pressures.
Implementation Method 1
an inner semiconductive layer formed of a conductive material mainly comprising a mixture blended 100 parts by weight of polyolefin based rubber or resin, 10 to 100 parts by weight of carbon black, and 0.3 to 3.0 parts by weight of aliphatic alkyl peroxide, the inner semi conductive layer being crosslinked by heating
Implementation Method 2
the inner semi conductive layer being crosslinked by heating
Data Source
Figure 1
AI summary
A water blocking power cable includes a cable core containing in this order a watertight conductor formed by twisting a plurality of wires filled with watertight material therebetween; an inner semiconductive layer formed of a conductive material mainly containing a mixture blended 100 parts by weight of polyolefin based rubber or resin, 10 to 100 parts by weight of carbon black, and 0.3 to 3.0 parts by weight of aliphatic alkyl peroxide, the inner semiconductive layer being crosslinked by heating; an insulating layer formed from an insulating coating material mainly containing polyolefin based rubber or resin; and an outer semiconductive layer.