HVDC Cable Insulation Blend With Low Conductivity and No Degassing
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Solution Overview
Problem
High voltage direct current (HVDC) cables face challenges with thermal runaway due to high electrical conductivity of insulation materials, which generates excessive heat and degrades mechanical properties, and existing crosslinking processes are cumbersome and costly, requiring degassing steps to remove volatile by-products.
Innovation Solution
A polymer composition comprising low density polyethylene (LDPE), polypropylene (PP), and a compatibilizer, which offers low electrical conductivity and improved thermomechanical resistance without the need for crosslinking agents, thereby reducing heat generation and eliminating the need for degassing procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinking agents are used to improve heat and deformation resistance, then mechanical strength and creep properties are improved, but volatile decomposition products are generated which negatively influence electrical properties and require time-consuming degassing steps
Solution Approach 1:
The invention extracts and eliminates the crosslinking agent from the polymer composition, achieving the desired mechanical strength through a blend of LDPE, polypropylene, and compatibilizer without requiring peroxide crosslinking. This removes the source of volatile decomposition products entirely.
Solution Approach 2:
The invention uses a simple thermoplastic polymer blend that does not require complex crosslinking chemistry. The composition achieves its mechanical properties through the synergistic combination of polymers and compatibilizer, eliminating the need for expensive crosslinking agents and subsequent degassing processes.
2Reliability
If conventional polymer compositions are used in HVDC cables, then electrical conductivity is sufficient for lower voltages, but thermal runaway occurs at higher voltages due to excessive heat generation from leakage current
Solution Approach 1:
The invention changes the electrical conductivity parameter of the insulation material by using a specific polymer blend composition. The combination of LDPE, polypropylene, and compatibilizer achieves lower DC electrical conductivity than conventional single-polymer compositions, reducing leakage current and heat generation at high voltages.
Solution Approach 2:
The invention uses a composite polymer blend consisting of LDPE, polypropylene, and compatibilizer. This multi-component system combines the advantages of different polymers to achieve both low electrical conductivity and good mechanical properties, preventing thermal runaway in HVDC applications.
3Temperature
If crosslinking processes are implemented to improve thermomechanical resistance, then heat and deformation resistance are enhanced, but production complexity increases due to additional crosslinking and degassing steps
Solution Approach 1:
The invention extracts the crosslinking step from the production process by using a thermoplastic polymer blend that achieves adequate mechanical properties without crosslinking. This simplifies the production process to a single extrusion step, eliminating crosslinking and degassing operations.
Solution Approach 2:
The polymer blend composition is designed to self-reinforce through the compatibilizer-mediated interaction between LDPE and polypropylene phases, achieving adequate thermomechanical resistance without external crosslinking agents or processes. The material serves its own reinforcement needs through its composition.
4Power
If higher voltages are applied to increase power transmission capacity, then cable efficiency is improved, but heat generation from leakage current increases proportionally to the square of the electrical field
Solution Approach 1:
The invention changes the electrical conductivity parameter of the insulation material to a lower value through the polymer blend. Since heat generation is proportional to conductivity times the square of the electrical field, reducing conductivity directly reduces heat generation even at high voltages, enabling safer power transmission.
Data Source
AI summary
The invention provides a polymer composition comprising a low density polyethylene (LDPE); polypropylene (PP) and a compatibiliser. The invention also relates to cables comprising said polymer composition and the use of the polymer composition in the manufacture of an insulation layer of cable.