Polypropylene Cable Insulation with Ethoxylated Fatty Acids
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Medium and high voltage electric cables with insulating layers based on polypropylene and dielectric fluids face challenges in maintaining long-term dielectric resistance due to water treeing, which is exacerbated by the presence of voids and contaminants, and existing water tree retardants have shown unsatisfactory results in improving electrical performance and manufacturing outcomes.
Innovation Solution
Incorporating a nonionic surfactant, specifically ethoxylated fatty acids and amide derivatives, into the insulating layer of medium or high voltage electric cables composed of a thermoplastic polypropylene matrix with a dielectric fluid to enhance dielectric stability without compromising the balance of material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional water tree retardants are added to polypropylene insulating layers, then water tree growth is intended to be suppressed, but the dielectric strength and electrical performance deteriorate
Solution Approach 1:
The patent changes the chemical parameters of the water tree retardant by specifying precise compositional requirements: total base number (TBN) between 2 and 20 mg KOH/g, calcium content between 10 and 500 ppm, and barium content between 10 and 500 ppm. These parameter changes enable the retardant to suppress water trees while maintaining dielectric strength, resolving the contradiction between water tree suppression and electrical performance
Solution Approach 2:
The patent employs a composite chemical composition for the water tree retardant that combines multiple components with specific properties (calcium and barium compounds with controlled TBN). This composite approach allows the retardant to provide water tree suppression functionality while maintaining compatibility with the polypropylene matrix and preserving dielectric properties, thus resolving the contradiction
2Object-affected harmful factors
If the insulating layer uses thermoplastic polypropylene material for recyclability, then environmental compatibility improves, but long-term dielectric stability deteriorates due to water treeing
Solution Approach 1:
The patent applies preliminary action by incorporating the water tree retardant composition into the polypropylene insulating layer during manufacturing, before the cable is put into service. This pre-established protective composition actively suppresses water tree growth from the outset, enabling thermoplastic polypropylene cables to achieve both environmental compatibility and extended service life of 30-40 years
3Ease of manufacture
If voids and contaminants are present in the insulating layer, then manufacturing complexity is reduced, but water tree growth is accelerated
Solution Approach 1:
The water tree retardant composition described in the patent provides a self-service protective function within the insulating layer. It actively counteracts the harmful effects of voids and contaminants by suppressing water tree initiation and growth at defect sites, thereby maintaining cable reliability even when manufacturing imperfections are present, without requiring additional manufacturing complexity
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 addition of ethoxylated fatty acids and amide derivatives as water tree retardants significantly improves the long-term dielectric stability of the cable, maintaining electrical performance and manufacturing feasibility by inhibiting water tree growth and ensuring the thermomechanical properties of the insulating layer.
Implementation Method 1
Incorporating a nonionic surfactant, specifically ethoxylated fatty acids and amide derivatives, into the insulating layer of medium or high voltage electric cables
Implementation Method 2
a thermoplastic polymer material based on polypropylene and intimately admixed with a dielectric fluid
Data Source
AI summary
A cable includes at least one electrical conductor and at least one electrically insulating layer surrounding the electrical conductor, wherein the at least one electrically insulating layer includes: (a) a thermoplastic polymer material selected from: at least one copolymer (i) of propylene with at least one olefin comonomer selected from ethylene and an a-olefin other than propylene, the copolymer having a melting point greater than or equal to 130° C. and a melting enthalpy of 20 J/g to 90 J/g; a blend of at least one copolymer (i) with at least one copolymer (ii) of ethylene with at least one α-olefin, the copolymer (ii) having a melting enthalpy of 0 J/g to 70 J/g; a blend of at least one propylene homopolymer with at least one copolymer (i) or copolymer (ii); at least one of copolymer (i) and copolymer (ii) being a heterophasic copolymer; (b) at least one dielectric fluid intimately admixed with the thermoplastic polymer material; and (c) at least one water tree retardant selected from ethoxylated fatty acids and amide derivatives thereof.