Insulated Wire Pore Segmentation for Dielectric Strength
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Solution Overview
Problem
Insulated electric wires used in high-voltage electrical equipment face issues with localized pore formation in insulating coatings, leading to decreased strength, insulating properties, and solvent resistance due to non-uniform dispersibility of thermally decomposable resin, resulting in larger pores and potential dielectric breakdown.
Innovation Solution
The development of an insulated electric wire with a method involving a resin varnish containing hollow-forming particles having a thermally decomposable core and a shell with projections on its surface, where the core decomposes to form pores and the shell remains intact, preventing pore communication and enhancing dispersibility, thus maintaining strength and insulating properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermally decomposable resin is used to form pores in the insulating coating, then the dielectric constant is reduced, but the pores become localized and communicate with each other, causing decreased strength and insulating properties
Solution Approach 1:
The insulating coating is segmented into multiple layers: a base insulating coating layer and an outer insulating coating layer. The pores are confined to the base layer only, while the outer layer remains substantially pore-free, creating a layered structure that separates the dielectric function from the mechanical strength function.
Solution Approach 2:
Different regions of the insulating coating have different properties: the base insulating coating layer has low dielectric constant due to pores, while the outer insulating coating layer has high mechanical strength and good insulating properties with substantially no pores. This local differentiation resolves the contradiction between dielectric performance and mechanical strength.
2Manufacturing precision
If thermally decomposable resin is uniformly dispersed in the insulating coating, then pores are evenly distributed, but achieving uniform dispersibility is difficult and pores still tend to communicate
Solution Approach 1:
The coating is divided into two layers with different pore contents. The base layer contains the pores for uniform dielectric properties, while the outer layer is substantially pore-free, ensuring reliable insulating properties regardless of pore distribution uniformity in the base layer.
Solution Approach 2:
The outer insulating coating layer acts as a protective cushion over the pore-containing base layer. This outer layer prevents the harmful effects of pore communication (decreased strength and insulating properties) while allowing the base layer to provide the desired dielectric characteristics.
3Reliability
If pores are formed in the insulating coating to reduce dielectric constant, then corona inception voltage is improved, but mechanical strength and solvent resistance decrease
Solution Approach 1:
The insulating coating is segmented into a base layer with pores for low dielectric constant and an outer pore-free layer that provides barrier properties against solvents and maintains mechanical strength, thus resolving the contradiction between electrical performance and chemical resistance.
Solution Approach 2:
Different layers have specialized functions: the base layer provides dielectric performance with pores, while the outer layer provides protective functions (mechanical strength, solvent resistance) without pores, achieving both requirements simultaneously.
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 effectively suppresses the decrease in strength, insulating properties, and solvent resistance while achieving a low dielectric constant, ensuring improved durability and uniformity of the insulating layer, even under mechanical stress like stretching or bending.
Implementation Method 1
a heating step of heating the applied resin varnish
Implementation Method 2
each of the outer shells has a plurality of projections on an outer surface thereof
Data Source
AI summary
An insulated electric wire includes a linear conductor and one or more of insulating layers formed on an outer peripheral surface of the conductor. In the insulated electric wire, at least one of the one or more of insulating layers has a plurality of pores, outer shells are disposed on peripheries of the pores, and each of the outer shells has a plurality of projections on an outer surface thereof.