Insulated Wire Flattened Bubbles Dielectric Breakdown
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Solution Overview
Problem
Insulated wires with bubble-containing insulating layers have high partial discharge inception voltage but relatively low dielectric breakdown voltage, necessitating a solution to enhance dielectric breakdown voltage while maintaining partial discharge inception voltage.
Innovation Solution
The development of insulated wires with a bubble-containing insulating layer featuring flattened bubbles, where the oblateness is between 1.5 and 5.0, and a thermosetting resin, such as polyester or polyamideimide, with a porosity of 70% or less, to increase dielectric breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bubble-containing insulating layer is used, then partial discharge inception voltage is increased, but dielectric breakdown voltage becomes relatively low
Solution Approach 1:
The patent changes the physical parameters of the bubbles by controlling their size (0.1-10 μm diameter) and distribution density (5-50 bubbles/mm²) to optimize both partial discharge inception voltage and dielectric breakdown voltage. This parameter optimization resolves the contradiction by finding the right balance point where both electrical properties are improved.
Solution Approach 2:
The patent creates local quality variations by distributing bubbles non-uniformly within the insulating layer, with higher concentration near the conductor surface and lower concentration toward the outer surface. This local differentiation allows the insulating layer to provide better partial discharge resistance near the high-stress region while maintaining adequate dielectric strength overall.
2Reliability
If porosity is increased to lower relative permittivity, then partial discharge inception voltage increases, but dielectric breakdown voltage decreases
Solution Approach 1:
The patent optimizes the porosity parameter to a specific range (10-70%) to balance the competing requirements. By controlling porosity within this range and combining it with controlled bubble parameters, the patent achieves both high partial discharge inception voltage and adequate dielectric breakdown voltage.
Solution Approach 2:
The patent creates a composite insulating layer structure combining solid insulating material with dispersed bubble phases. This composite structure allows the material to exhibit both low relative permittivity (from the air-filled bubbles) and high dielectric strength (from the solid matrix), resolving the contradiction between partial discharge performance and breakdown voltage.
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 increases dielectric breakdown voltage while maintaining high partial discharge inception voltage, making the insulated wires suitable for high-voltage applications in rotating electrical machines.
Implementation Method 1
the flattened bubbles are formed by compression in the thickness direction of an insulating layer having bubbles
Data Source
AI summary
An insulated wire comprising a conductor and a bubble-containing insulating layer, directly or indirectly coating the outer periphery of the conductor and containing a thermosetting resin, wherein the bubbles in the bubble-containing insulating layer include flattened bubbles whose oblateness in the cross-section perpendicular to the longitudinal direction of the insulated wire (lateral length of the bubble cross-sectional shape/vertical length of the bubble cross-sectional shape) is 1.5 or more and 5.0 or less.