Power Cable Insulating Tape Composition to Prevent Local Cracking
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Solution Overview
Problem
The existing methods for forming an insulating coating on power cables using insulating tape result in local cracking due to bleeding-out of antioxidants, which inhibit fusion and crosslinking of polyethylene, leading to durability issues during long-term use.
Innovation Solution
An insulating tape with a low molecular weight antioxidant (190-1050) is used, which is easily reabsorbed by polyethylene during crosslinking, and a method involving preheating and controlled crosslinking conditions is employed to prevent local cracking and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an antioxidant with large molecular volume and low mobility is used to reduce bleeding-out, then bleeding resistance is improved, but the antioxidant cannot be reabsorbed by polyethylene during crosslinking, causing local cracking
Solution Approach 1:
The patent changes the molecular weight parameter of the antioxidant from large (polycyclic compounds) to moderate (190-1050), and adjusts the concentration parameter (0.05-0.8 parts by mass). This parameter optimization allows the antioxidant to have sufficient bleeding resistance while maintaining mobility for reabsorption during crosslinking, preventing local cracking.
2Temperature
If polyethylene is crosslinked by heating, then heat resistance is improved, but bleeding-out of antioxidant inhibits fusion and causes local cracking
Solution Approach 1:
The patent performs preliminary action by selecting an antioxidant with appropriate molecular weight (190-1050) and concentration (0.05-0.8 parts by mass) that can be reabsorbed during the heating crosslinking process. This preliminary selection ensures that when heating occurs, the antioxidant migrates back into the polyethylene matrix before fusion, preventing local cracking while maintaining heat resistance.
3Reliability
If hydrophilicity of polyethylene is increased to suppress water treeing, then water tree resistance is improved, but antioxidant bleeding-out increases due to large surface area to volume ratio in insulating tape
Solution Approach 1:
The patent changes the molecular weight parameter of the antioxidant to a moderate range (190-1050), which provides an optimal balance between bleeding resistance and reabsorption capability. This parameter adjustment compensates for the increased bleeding tendency caused by high hydrophilicity and large surface area to volume ratio in the insulating tape structure.
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 effectively suppresses local cracking in the insulating coating, ensuring the durability and longevity of the power cable by allowing the antioxidant to be reabsorbed, thus preventing fusion inhibition and enhancing mechanical properties and heat resistance.
Implementation Method 1
the antioxidant is dissolved again in the resin material during crosslinking
Implementation Method 2
a method involving preheating and controlled crosslinking conditions is employed
Data Source
AI summary
An insulating tape, for coating a connection portion of a power cable, includes a resin material which includes polyethylene at least partially modified by a molecule imparting hydrophilicity, an antioxidant, and a crosslinking agent. The antioxidant has a molecular weight in a range of 190 or more and less than 1050. The antioxidant has a content in a range of 0.05 parts by mass or more and 0.8 parts by mass or less, with respect to 100 parts by mass of the polyethylene. The insulating tape has a thickness in a range of 50 μm or more and 250 μm or less.