Polyethylene Power Cable Insulation for Heat Aging Resistance
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Solution Overview
Problem
Existing power cables with entirely crosslinked polyethylene insulation layers suffer from inadequate heat aging resistance due to the presence of non-crosslinked polyethylene, which undergoes heat deterioration and promotes further deterioration of crosslinked polyethylene.
Innovation Solution
Incorporating a specific ratio of crosslinked and non-crosslinked polyethylene in the insulation layer, with the non-crosslinked polyethylene having a controlled molecular weight range and gel fraction, and using an antioxidant to prevent oxidation, thereby stabilizing the insulation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-crosslinked polyethylene is present in the insulation layer, then flexibility is maintained, but heat deterioration occurs which promotes further deterioration of crosslinked polyethylene
Solution Approach 1:
The patent converts the harmful effect of non-crosslinked polyethylene heat deterioration into a beneficial protective mechanism. By controlling the molecular weight to 5000-25000, the non-crosslinked portions deteriorate preferentially under heat stress, acting as sacrificial elements that absorb thermal degradation and protect the crosslinked network, thus improving overall heat aging resistance while maintaining flexibility
Solution Approach 2:
The patent applies parameter changes by specifying a narrow molecular weight range (5000-25000 number average) for non-crosslinked polyethylene. This precise parameter control ensures the non-crosslinked portions have optimal heat deterioration characteristics that protect the crosslinked structure, transforming what was previously a harmful factor into a protective mechanism
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 insulation layer exhibits improved heat aging resistance, maintaining flexibility and insulation properties over extended periods, even under harsh conditions.
Implementation Method 1
non-crosslinked polyethylene tends to undergo micro-Brownian motion or macro-Brownian motion by heat to be more liable to undergo heat deterioration than crosslinked polyethylene
Implementation Method 2
The radicals of the non-crosslinked polyethylene produced by the heat deterioration bind to oxygens to form deterioration points
Implementation Method 3
the non-crosslinked polyethylene has a number average molecular weight of 5000 or more and 25000 or less, thereby making it possible to improve heat aging resistance of the insulation layer
Data Source
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AI summary
This power cable includes a conductor and an insulation layer covering the outer circumference of the conductor and constituted from a resin composition containing a polyethylene, wherein the insulation layer contains, in the polyethylene, a crosslinked polyethylene that is insoluble in xylene at 120°C and a non-crosslinked polyethylene that is soluble in xylene at 120°C, and the non-crosslinked polyethylene has a number average molecular weight of 5000 or more and 25000 or less.