Composite Insulator Winding Angles for SF6 Volume Reduction
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Solution Overview
Problem
Existing composite insulators have a larger internal volume than ceramic insulators due to their barrel shape, leading to a greater quantity of SF6 gas and increased environmental impact.
Innovation Solution
The insulator is designed with a first and second chamber, each comprising a frustoconical and cylindrical part, with an inner and outer sleeve made of composite material by helical winding of fiberglass, where the winding angles and thermal expansion coefficients are strategically controlled to allow for assembly and reduced volume, and optionally made in a single piece using a soluble mandrel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a composite insulator is made with a barrel shape, then the internal volume and SF6 gas quantity increase, but the structural strength and stability improve
Solution Approach 1:
The insulator is divided into multiple chambers (first chamber and second chamber) with different geometric configurations. Each chamber is further segmented into frustoconical parts and cylindrical parts, allowing differential thermal expansion management while maintaining overall structural integrity and reducing total SF6 volume.
Solution Approach 2:
The insulator uses composite material construction with fiberglass filaments wound at different angles in different regions. The frustoconical parts use higher winding angles for strength, while cylindrical parts use lower winding angles for thermal expansion control, creating a composite structure that simultaneously achieves strength and volume reduction.
2Strength
If the winding angle of fiberglass filament is increased, then the structural strength improves, but the coefficient of thermal expansion decreases
Solution Approach 1:
Different regions of the insulator have different fiberglass winding angles optimized for their specific functions. The frustoconical parts use higher winding angles (closer to 90 degrees) for maximum strength, while the cylindrical parts use lower winding angles to control thermal expansion, creating local quality variations throughout the structure.
Solution Approach 2:
The patent explicitly utilizes thermal expansion principles by controlling the fiberglass winding angles to achieve desired expansion coefficients. The cylindrical parts with lower winding angles have higher thermal expansion coefficients, allowing them to compensate for expansion in other regions, while frustoconical parts with higher winding angles provide structural strength with controlled expansion.
3Device complexity
If the insulator is made as a single piece using soluble mandrel, then the manufacturing complexity reduces, but the assembly precision and thermal expansion control decrease
Solution Approach 1:
The insulator is manufactured as separate components (first chamber, second chamber, inner sleeve, outer sleeve) using soluble mandrels, then assembled together. This segmentation allows each component to be precisely manufactured and controlled independently, maintaining manufacturing precision while using the simple soluble mandrel process.
Solution Approach 2:
The soluble mandrel acts as a temporary intermediary structure during manufacturing. It allows complex chamber shapes to be formed easily, then dissolves away, leaving precise cavities. This intermediary approach enables both manufacturing simplicity and final product precision.
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 design reduces the internal volume and SF6 gas quantity, minimizing environmental impact by allowing for precise control of thermal expansion and assembly, and in some cases, eliminating the need for separate chamber assembly.
Implementation Method 1
the inner sleeve, the first and second chambers and the outer sleeve are made of composite material by helical winding of a fiberglass filament, the winding angle (defined with respect to the axis of symmetry of the cylinder) of the filament which constitutes the outer sleeve being smaller than the winding angle of the glass fiber which constitutes the first and the second chambers, the winding angle of the filament which constitutes the inner sleeve being greater than the winding angle of the fiberglass which constitutes the first and the second chambers
Implementation Method 2
the coefficient of thermal expansion of the material of the inner sleeve is less than the coefficient of thermal expansion of the material of the first and second chambers and that the coefficient of thermal expansion of the material of the outer sleeve is greater than the coefficient of thermal expansion of the material of the first and second chambers
Data Source
Figure 1~2
Figure 3~5
AI summary
The insulator (2) has two chambers (4, 6) and an external sleeve that are made of a composite material by helically winding a glass fiber filament. A winding angle of the filament constituting the external sleeve is smaller than a winding angle of glass fiber constituting the chambers while a winding angle of the filament constituting an interior sleeve is larger than the winding angle of the glass fiber constituting the chambers. The interior sleeve is placed inside the chambers, and the external sleeve is placed outside the chambers.