Cable Insulation Extrusion With Premixed Nanofillers for Dielectric Stability
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Solution Overview
Problem
Existing methods for manufacturing electric cables with thermoplastic insulating layers face challenges in achieving homogeneous distribution of nanofillers, leading to agglomeration and reduced electrical performance due to large inorganic particle effects, which degrade the electric field and increase space charge accumulation.
Innovation Solution
A manufacturing process involving premixing nanofillers with a dielectric liquid to create a homogeneous distribution, followed by mixing with thermoplastic polymer in an extruder, ensuring each nanofiller is surrounded by dielectric liquid to prevent agglomeration and allowing for filtration of impurities, resulting in improved dielectric breakdown resistance and reduced space charge accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If nanofillers are mixed directly with thermoplastic polymer and dielectric liquid in the extruder, then the manufacturing process is simpler, but nanofiller distribution becomes heterogeneous leading to agglomeration and reduced electrical performance
Solution Approach 1:
The patent applies preliminary action by premixing nanofillers with dielectric liquid before introducing them to the extruder. This pre-preparation step ensures nanofillers are uniformly dispersed in the liquid medium, preventing agglomeration during subsequent extrusion. The intermediate composition is prepared in advance and then combined with thermoplastic polymer in the extruder, maintaining both precision and process efficiency.
Solution Approach 2:
The patent uses dielectric liquid as an intermediary substance to facilitate uniform distribution of nanofillers. The liquid acts as a carrier medium that enables homogeneous dispersion of nanofillers before they are incorporated into the polymer matrix. This intermediary approach prevents direct contact between nanofiller particles and polymer, avoiding agglomeration while simplifying the overall mixing process.
2Reliability
If nanofillers are not premixed with dielectric liquid, then the manufacturing process is faster, but large particle agglomerates form causing local electric field changes and interface degradation
Solution Approach 1:
The premixing step prepares the intermediate composition in advance, ensuring nanofillers are uniformly distributed in dielectric liquid before extrusion. This preliminary dispersion prevents the formation of large agglomerates that would compromise dielectric strength, while the efficient mixing process maintains acceptable manufacturing cycle times.
Solution Approach 2:
The patent changes the physical state and distribution parameters of nanofillers by dispersing them in dielectric liquid at controlled concentrations. This parameter adjustment ensures nanofillers remain as individual particles or small clusters rather than large agglomerates, maintaining dielectric breakdown resistance while enabling continuous production.
3Manufacturing precision
If nanofillers are homogeneously distributed in the insulating layer, then volume resistivity increases and space charge accumulation reduces, but the mixing process becomes more complex requiring premixing steps
Solution Approach 1:
The patent performs preliminary mixing of nanofillers with dielectric liquid to create a homogeneous intermediate composition before introducing it to the extruder. This pre-dispersion step ensures uniform nanofiller distribution in the final insulating layer, achieving the desired manufacturing precision while consolidating mixing operations into two distinct stages.
Solution Approach 2:
Dielectric liquid serves as an intermediary carrier that facilitates homogeneous distribution of nanofillers. By using this liquid medium, the patent achieves uniform nanofiller dispersion without requiring complex multi-stage mixing equipment, as the liquid naturally promotes even distribution during the premixing and extrusion processes.
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 process ensures a homogeneous distribution of nanofillers, enhancing the cable's resistance to dielectric breakdown and volume resistivity, while reducing space charge accumulation, thereby improving the electrical performance of medium and high voltage cables.
Implementation Method 1
homogeneous distribution of nanofillers, which leads to a homogeneous distribution of nanofillers in the extrusion composition. This premixing allows each nanofiller to be surrounded by a layer of dielectric liquid, thus separating it from the others
Implementation Method 2
a step of applying the extrusion composition from step (ii) at the extruder head around the elongated electrically conductive element
Implementation Method 3
nanocomposites induce improved electrical properties because the electric field is modulated by the nanoparticles. In particular, in high-voltage direct current (HVDC) applications, nanocomposites benefit from lower space charge phenomena and higher volume resistivity
Implementation Method 4
homogeneously distributed nanocharges can increase the resistance to dielectric breakdown in both alternating and direct currents of insulating compounds
Data Source
Figure 1~2
AI summary
The invention relates to a method for manufacturing an electrical cable characterized in that it comprises at least the following steps: i) a step of mixing an extrusion composition comprising at least one thermoplastic polymer in the form of solid particles, a dielectric liquid and at least one nanofiller, ii) a step of introducing said extrusion composition into a feeding zone of a barrier screw located at the inlet of an extruder, and iii) a step of applying at the level of an extruder head the extrusion composition from step ii) around an elongated electrically conductive element, said method being characterized in that the mixing step i) comprises a step of premixing the dielectric liquid with said at least one nanofiller to obtain an intermediate composition which is then mixed with said at least one thermoplastic polymer to obtain the extrusion composition.