Multilayer Electric Field Grading for High-Voltage Joint Stress Relief
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Solution Overview
Problem
Existing electric field grading technologies face challenges in balancing cost, safety, and electric field management, particularly at high voltage levels and in shrinking component sizes, where insulation thickness affects electric field strength and temperature, leading to potential breakdowns.
Innovation Solution
A multilayer electric field grading article comprising layers with compositionally different particles in matrix materials, forming a discrete interface to achieve synergistic electric field grading performance with higher onset voltage and nonlinearity, enhancing irreversible breakdown voltage and mitigating electrical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If insulation thickness is reduced to lower material costs and temperatures, then cost and temperature are improved, but electric field strength increases leading to potential breakdown
Solution Approach 1:
The patent divides the grading layer into multiple sub-layers with different material compositions and thicknesses. Each sub-layer is optimized to address specific electric field distribution challenges, allowing the system to achieve effective field grading with reduced overall insulation thickness while maintaining safety margins against breakdown.
Solution Approach 2:
The patent employs composite materials consisting of multiple layers with different dielectric properties, conductive fillers, and polymer matrices. These composite structures enable tailored electric field distribution characteristics that single-material solutions cannot achieve, allowing thinner overall insulation while compensating for higher local field strengths through strategic material placement.
2Reliability
If conventional single-layer grading materials are used, then device complexity is low, but electric field grading performance is insufficient at high voltage levels
Solution Approach 1:
The grading layer is segmented into multiple functional sub-layers, each with specific thicknesses and material compositions optimized for particular voltage ranges or field distribution requirements. This segmentation enables superior overall performance at high voltage levels while keeping each individual layer relatively simple to manufacture.
Solution Approach 2:
Different regions of the multilayer structure have locally optimized properties - certain layers contain higher concentrations of conductive fillers like carbon black or metal particles, while others use polymers with specific dielectric constants. This local quality variation allows the structure to handle high voltage stresses effectively without requiring complex designs throughout the entire insulation system.
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 multilayer approach provides improved electric field management with higher onset voltage and nonlinearity, effectively reducing electrical stress in high-voltage applications, such as cable terminations and splices, while maintaining reversibility and operational stability across a wide temperature range.
Implementation Method 1
Each electric field grading composition shows reproducible nonlinear electric field switchable electrical conductivity with respect to applied electric field
Implementation Method 2
capacitive field grading (e.g., geometrical electrode grading with appropriate shape of conductive parts, refractive grading with high-permittivity materials, and condenser grading with integration of metallic elements)
Implementation Method 3
resistive field grading, using special materials with appropriate current-field characteristics
Implementation Method 4
Each electric field grading composition shows reproducible nonlinear electric field switchable electrical conductivity with respect to applied electric field
Implementation Method 5
The electrical conductivity of such compositions may depend on percolation properties of the conductive filler particles
Data Source
AI summary
A multilayer electric field grading article comprises first and second layers forming a discrete interface. The first layer comprises a first electric field grading composition comprising first particles dispersed in a first matrix material. The second layer comprises a second electric field grading composition comprising second particles, compositionally different than the first particles, dispersed in a second matrix material. The first and second layers have respective first and second degrees of nonlinearity between respective first and second onset voltages and corresponding first and second breakdown voltages. The first and second layers taken together have a combined onset voltage that is higher than the first and second onset voltages, and the first and second layers taken together have a greater combined degree of nonlinearity than each of the first and second degrees of nonlinearity taken individually. A method of reducing electric field stress at a joint or termination of a substrate includes applying the multilayer electric field grading article to a surface of a substrate.