Peroxide-Free Cable Insulation Composition for Low DC Conductivity
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Solution Overview
Problem
Existing power cable polymer compositions for high voltage direct current (HV DC) applications face challenges with high direct current (DC) electrical conductivity, leading to heat generation and thermal runaway, and require costly and time-consuming degassing steps to remove volatile decomposition products from crosslinking agents.
Innovation Solution
A power cable polymer composition using single site polyethylene (SSPE), specifically medium density polyethylene (MDPE) or high density polyethylene (HDPE) homopolymer or copolymer, produced without crosslinking agents, which reduces DC electrical conductivity to 3.0 fS/m or less, maintaining mechanical properties and eliminating the need for degassing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinking agents (peroxides) are used to improve mechanical strength and heat resistance, then the polymer layer gains improved creep properties and mechanical strength, but volatile decomposition products are generated that negatively influence electrical properties and require additional degassing steps
Solution Approach 1:
The invention extracts and removes the harmful crosslinking agent (peroxide) from the polymer composition entirely. By using a peroxide-free polymer composition, the source of volatile decomposition products is eliminated, thereby resolving the contradiction between gaining mechanical strength through crosslinking and avoiding harmful volatile by-products that degrade electrical properties.
Solution Approach 2:
The invention replaces the conventional crosslinking approach with a thermoplastic polymer composition that achieves mechanical strength without permanent crosslinks. The polymer relies on physical entanglement and intermolecular forces rather than chemical crosslinks, eliminating the need for peroxide agents and subsequent degassing operations.
2Reliability
If degassing steps are implemented to remove volatile decomposition products, then electrical properties are improved, but production time and energy consumption increase
Solution Approach 1:
The invention extracts and eliminates the need for degassing steps by removing the source of volatile decomposition products (peroxide crosslinking agents) from the system. The peroxide-free polymer composition produces no harmful volatiles during service, making the time-consuming degassing operation unnecessary and thereby reducing production time and energy consumption while maintaining excellent electrical properties.
Solution Approach 2:
The invention performs preliminary action by formulating a peroxide-free polymer composition from the outset, preventing the generation of volatile decomposition products before they can affect electrical properties. This proactive approach eliminates the need for subsequent degassing steps, streamlining the production process.
3Reliability
If high DC electrical conductivity is present in the insulation material, then electrical leakage current increases, but heat generation and thermal runaway risk increase
Solution Approach 1:
The invention changes the DC electrical conductivity parameter of the polymer composition to an optimized range (≤1.0 fS/m at 20°C). By controlling the polymer structure and composition to achieve ultra-low DC conductivity, the invention minimizes electrical leakage current and the associated heat generation, thereby preventing thermal runaway while maintaining excellent electrical insulation properties.
Data Source
Figure 1
AI summary
The invention relates to power cable polymer composition which comprises a single site polyethylene (SSPE), a power cable, for example, a high voltage direct current (HV DC), a power cable polymer insulation, use of a polymer composition for producing a layer of a power cable, and a process for producing a power cable.