Thermoplastic Cable Insulation With Nitrile Additives for High Temperatures
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Solution Overview
Problem
Medium- and high-voltage cables face challenges with crosslinked polyolefin insulating layers, which are non-recyclable, require specific and costly production conditions, and can degrade due to premature crosslinking, while alternative thermoplastic layers limit operating temperature and power transmission capabilities.
Innovation Solution
A cable design incorporating a thermoplastic polymer material and a compound with a nitrile group, which enhances dielectric breakdown strength and operating temperature up to 90-110°C, using a mineral oil-based dielectric liquid with a controlled polar compound content to minimize dielectric losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a crosslinked polyolefin layer is used for the electrically insulating layer, then the cable can function at temperatures above 70°C with satisfactory electrical and mechanical properties, but the material cannot be recycled and requires specific reaction conditions that reduce manufacturing rate and increase production cost
Solution Approach 1:
The patent changes the fundamental parameter of the insulating material from crosslinked to thermoplastic, eliminating the need for crosslinking reactions while achieving high-temperature performance (up to 90-110°C) through the thermoplastic polymer composition itself, thereby simplifying manufacturing and enabling recycling
Solution Approach 2:
The patent uses a composite material system combining thermoplastic polymer with specific additives (compounds containing nitrile groups, antioxidants, and controlled polar compounds) to achieve the electrical and thermal performance previously only available from crosslinked materials, while maintaining thermoplastic processability
2Reliability
If a crosslinked polyolefin layer is used for the electrically insulating layer, then satisfactory electrical and mechanical properties are achieved, but premature crosslinking may occur in the extruder and/or extruder head leading to degradation of layer quality and dielectric properties
Solution Approach 1:
The patent changes the material state from crosslinked to thermoplastic, eliminating the crosslinking reaction entirely. This prevents premature crosslinking in the extruder while maintaining high dielectric strength and reliability, allowing for faster, more reliable manufacturing without reaction control issues
3Ease of manufacture
If a thermoplastic layer of low-density polyethylene or high-density polyethylene is used for the electrically insulating layer, then the cable can be manufactured with simpler processes, but the cable cannot function at temperatures above about 70°C for LDPE or above 80°C for HDPE, limiting power transmission capability
Solution Approach 1:
The patent creates a composite thermoplastic material system that combines base polymer with specific functional additives (nitrile-containing compounds, antioxidants, controlled polar compounds) to achieve high-temperature stability (90-110°C) while maintaining thermoplastic processability and manufacturing simplicity
Solution Approach 2:
The patent modifies the thermal parameters of thermoplastic materials by incorporating compounds with specific functional groups and properties, raising the operating temperature range from the typical 70-80°C of standard thermoplastics to 90-110°C, thereby enabling high-power transmission applications
4Strength
If the dielectric liquid contains polar compounds, then the dielectric breakdown strength may be improved, but the dielectric losses increase and water absorption occurs leading to formation of defects in the insulating layer
Solution Approach 1:
The patent optimizes the parameter of polar compound content to a controlled, limited amount rather than using high concentrations. This balanced approach achieves sufficient dielectric breakdown strength while minimizing dielectric losses and water absorption, preventing defect formation in the insulating layer
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 solution provides a recyclable, high-performance electrically insulating layer with improved dielectric breakdown strength and reduced dielectric losses, enabling efficient power transmission at elevated temperatures without the drawbacks of crosslinked materials.
Implementation Method 1
at least one compound comprising at least one nitrile group... which enhances dielectric breakdown strength
Implementation Method 2
using a mineral oil-based dielectric liquid with a controlled polar compound content to minimize dielectric losses
Data Source
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Figure 3
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AI summary
Cable comprising at least one elongated electrically conducting element and at least one covering layer obtained from a polymer composition, wherein the polymer composition comprises at least one thermoplastic polymer material and at least one compound comprising at least one nitrile group.