Polyolefin Cable Insulation for DC Power Applications
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Solution Overview
Problem
High voltage and extra high voltage power cables face challenges in maintaining optimal electrical properties, particularly in direct current (DC) applications, where the conductivity of insulation materials can lead to thermal runaway and increased heat generation, necessitating the development of polymer compositions with reduced electrical conductivity while maintaining mechanical strength and resistance.
Innovation Solution
A polymer composition comprising a polyolefin obtained through a high-pressure process using a non-mineral oil compressor lubricant blended with an inorganic filler, which reduces electrical conductivity and is suitable for high voltage DC power cables, offering improved heat and deformation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer materials are used in high voltage DC cables, then mechanical strength and resistance are maintained, but electrical conductivity increases leading to thermal runaway and heat generation
Solution Approach 1:
The patent applies composite materials by combining polyolefin polymer matrix with inorganic filler particles to create a composite insulation material. This composite structure reduces electrical conductivity while maintaining mechanical strength, preventing thermal runaway in high voltage DC cable applications
Solution Approach 2:
The patent changes the electrical conductivity parameter of the insulation material by incorporating inorganic filler at optimized concentrations. This parameter modification reduces leakage current and heat generation while preserving the mechanical properties required for cable insulation
2Strength
If peroxide crosslinking is used to improve mechanical properties, then heat and deformation resistance increase, but volatile decomposition products are generated requiring costly degassing steps
Solution Approach 1:
The patent modifies the crosslinking chemistry by selecting peroxides with decomposition temperatures and product profiles optimized for cable processing. This changes the decomposition parameters to minimize volatile generation while achieving required crosslink density for heat and deformation resistance
Solution Approach 2:
The patent converts the potentially harmful volatile decomposition products into manageable by-products by selecting peroxides that decompose into non-volatile or minimally volatile substances. This transforms the crosslinking process from a source of harmful emissions to a beneficial crosslinking mechanism
3Productivity
If high production speed is maintained in cable manufacturing, then productivity increases, but electrical properties of insulation material deteriorate
Solution Approach 1:
The patent incorporates inorganic filler and crosslinking agents during the extrusion process itself, performing the material preparation in advance. This preliminary action allows high production speeds without compromising electrical properties, as the material is pre-optimized for both processing and 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
The polymer composition achieves low electrical conductivity, minimizing heat formation in insulation layers, making it suitable for high voltage DC power cables, including those operating at voltages up to 900 kV, while maintaining mechanical properties and reducing the need for costly degassing steps.
Implementation Method 1
the polymer composition achieves low electrical conductivity, minimizing heat formation in insulation layers
Implementation Method 2
offering improved heat and deformation resistance
Implementation Method 3
offering improved heat and deformation resistance
Data Source
AI summary
The invention relates to polymer composition comprising a polyolefin (a) and an inorganic filler (b) wherein the polyolefin (a) is obtainable by a high pressure process which process comprises the steps: (i) compressing one or more monomer(s) under pressure in a compressor, using a compressor lubricant for lubrication, (ii) polymerising a monomer optionally together with one or more comonomer(s) in a polymerisation zone, (iii) separating the obtained polyolefin (a) from the unreacted products and recovering the separated polyolefin (a) in a recovery zone, wherein in step (i) the compressor lubricant comprises a non-mineral oil, power cable, for example a direct current (DC) power cable, use of a polymer composition and a process for producing a DC power cable.