High-Voltage Cable Insulator Using Composite Material
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Solution Overview
Problem
High-voltage electronic device cables face challenges with EP rubber compositions that have low withstand voltage characteristics due to high temperature dependence of volume resistivity, leading to dielectric breakdown, especially in DC power cables with reduced diameters.
Innovation Solution
A cable design utilizing a high-voltage insulator made from an insulating composition with a specific silica-to-olefin-based polymer ratio, where the silica has a specific surface area of 150-250 m2/g and pH of 4-4.5, providing low temperature dependence of volume resistivity, ensuring excellent withstand voltage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If EP rubber composition with low dielectric constant is used as high-voltage insulator to reduce cable diameter, then cable outside diameter and capacitance are reduced, but volume resistivity greatly lowers as temperature increases due to high temperature dependence, causing dielectric breakdown
Solution Approach 1:
The patent uses a composite material consisting of EP rubber base resin combined with specific inorganic fillers (such as aluminum oxide, aluminum hydroxide, magnesium hydroxide, or titanium oxide) to create a high-voltage insulator composition. This composite structure maintains the low dielectric constant of EP rubber for cable diameter reduction while the inorganic fillers provide high volume resistivity even at elevated temperatures, preventing dielectric breakdown and improving withstand voltage characteristics.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the insulator material by controlling the composition ratios, particle sizes, and surface treatments of the inorganic fillers. By adjusting these parameters, the insulator achieves both low dielectric constant (for small diameter) and high volume resistivity with low temperature dependence (for reliability), resolving the contradiction between cable size reduction and voltage withstand capability.
2Weight of moving object
If EP rubber composition is used as high-voltage insulator, then cable is light-weighted and flexible, but volume resistivity greatly lowers as temperature increases due to high temperature dependence
Solution Approach 1:
The patent creates a composite material where EP rubber provides light weight and flexibility while inorganic fillers (aluminum oxide, aluminum hydroxide, magnesium hydroxide, or titanium oxide) provide thermal stability and high volume resistivity. This composite structure maintains the advantageous properties of EP rubber while compensating for its high temperature dependence of volume resistivity.
Solution Approach 2:
By modifying the compositional parameters and adding inorganic fillers with specific properties, the patent changes the thermal and electrical parameters of the insulator material to achieve low temperature dependence of volume resistivity while preserving the light weight and flexibility characteristics.
3Volume of moving object
If high-voltage insulator thickness is reduced to achieve smaller diameter cable, then cable outside diameter is reduced, but electric field concentrates near interface between outer semiconductive layer and high-voltage insulator, causing dielectric breakdown
Solution Approach 1:
The patent uses a composite insulator material with inorganic fillers that have high dielectric strength and uniform distribution properties. This composite structure allows for thinner insulator design while maintaining adequate electric field distribution, preventing concentration at the interface between the outer semiconductive layer and high-voltage insulator.
Solution Approach 2:
By changing the material parameters of the insulator (composition, filler content, particle size distribution), the patent improves the electric field distribution characteristics, allowing reduced insulator thickness without causing dielectric breakdown from electric field concentration.
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 cable achieves a small diameter with improved withstand voltage characteristics, maintaining insulation performance even at elevated temperatures, thus addressing the limitations of existing EP rubber compositions.
Implementation Method 1
the volume resistivity greatly lowers as temperature increases due to high temperature dependence of the volume resistivity
Data Source
AI summary
A cable for high-voltage electronic devices including an inner semiconductive layer, a high-voltage insulator, an outer semiconductive layer, a shielding layer, and a sheath which are provided on an outer periphery of a cable core part in the order mentioned, wherein the high-voltage insulator is made of an insulating composition whose temperature dependence parameter DR found by the following expression is 1.0 or less: DR=log R23° C.−log R90° C. (where R23° C. is volume resistivity (Ω·cm) at 23° C. and R90° C. is volume resistivity (Ω·cm) at 90° C.). The cable for high-voltage electronic devices is small in diameter and has an excellent withstand voltage characteristic.