Cupric Oxide Field Grading Composition for Cable Joint Stress Relief
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Solution Overview
Problem
Existing electric field grading technologies face challenges in balancing cost, safety, and electric field reduction, particularly at critical regions like interfaces or triple points in electrical power cable accessories, where high electric fields can lead to breakdown and failure.
Innovation Solution
The use of particulate cupric oxide dispersed in a dielectric matrix, which exhibits a reversible electric field switchable current-voltage relationship following the Power Law (I=kVα), effectively reducing electric field stress by varying conductivity with applied voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thinner insulation is used, then material cost and operating temperature are reduced, but electric field enhancement increases leading to breakdown risk
Solution Approach 1:
The patent applies electric field grading materials with different electrical properties at specific critical locations (interfaces, triple points, terminations) where field enhancement occurs. This localized application of specialized materials allows thin insulation design while maintaining reliability at critical regions through controlled field distribution.
Solution Approach 2:
The patent employs composite electric field grading materials combining conductive and insulating properties in controlled ratios. These composite materials enable simultaneous achievement of electrical stress control and space efficiency, allowing reduced insulation thickness without compromising breakdown strength.
2Reliability
If capacitive field grading materials with high dielectric constant are used, then electric field control is improved, but material complexity and processing difficulty increase
Solution Approach 1:
The patent modifies the electrical parameters of grading materials by controlling filler particle concentration, size distribution, and morphology. This allows tuning of dielectric constant and conductivity to achieve optimal field control while using simpler base materials and processing methods.
Solution Approach 2:
The patent employs readily available filler materials with controlled properties rather than requiring specialized expensive materials. By using common fillers with adjusted concentrations and particle characteristics, the patent achieves field grading functionality with simpler, more accessible materials.
3Reliability
If resistive field grading materials are used, then electric field redistribution is achieved, but material conductivity control becomes more sensitive to processing variations
Solution Approach 1:
The patent divides the grading material into discrete filler particles dispersed in a matrix, where individual particle properties can be controlled independently. This segmentation allows precise control of overall conductivity through particle concentration and distribution rather than requiring uniform properties throughout the entire material.
Solution Approach 2:
The patent controls conductivity by adjusting multiple parameters including filler concentration, particle size distribution, and morphology. This multi-parameter control approach provides robustness against processing variations, as changes in one parameter can be compensated by adjustments in others to maintain target conductivity.
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
This approach provides a reliable and efficient method to mitigate electric field stress at conductive substrate joints or terminations, ensuring safe operation across a wide temperature range while maintaining low electric fields, thus preventing failure.
Implementation Method 1
The electrical conductivity of such compositions may depend on percolation properties of the conductive filler particles
Implementation Method 2
exhibits a reversible electric field switchable current-voltage relationship that substantially follows the equation (i.e., Power Law): I=kVα
Data Source
AI summary
Electric field grading compositions comprise a particulate cupric oxide dispersed in a matrix material, wherein the electric field grading composition has a threshold voltage, a breakdown voltage, and exhibits a reversible electric field switchable current-voltage relationship that substantially follows the equation:I=kVαwherein: I is current in amperes; k is a constant greater than 0; V is applied voltage in volts, wherein V is between the threshold voltage and the breakdown voltage, inclusive; and α is a real number greater than 1. The electric field grading composition is useful for reducing electric field stress at a joint or termination of a conductive substrate. Articles including the electric field grading disposed on a surface of a conductive substrate are also disclosed.