Prestressed Bushing Structure to Prevent Creep and Stress Relaxation
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Solution Overview
Problem
Conventional oil-impregnated paper bushings with composite insulators suffer from creep and stress relaxation under prolonged tensile and compressive forces, leading to mechanical instability and increased transportation costs, especially in high-altitude and earthquake-prone regions.
Innovation Solution
A bushing design featuring a conductive tube and central tube, where the central tube is subjected to a compressive force in its extending direction, while the conductive tube experiences a tensile force, ensuring a tight connection and preventing stress relaxation through a manufacturing method that involves fixed connections and applied prestresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a composite insulator is used to replace the ceramic shell, then the bushing becomes more adaptable to high altitude and earthquake risk regions, but creep or stress relaxation occurs during the service life
Solution Approach 1:
The bushing is divided into separate functional components: a conductive tube for current conduction and a central tube for mechanical support. This segmentation allows each component to be optimized independently - the central tube provides rigid structural support while the conductive tube handles electrical functions, preventing stress relaxation in the composite insulator material.
Solution Approach 2:
The central tube acts as an intermediary mechanical support element between the composite insulator and the connecting assemblies. It bears the compressive forces and provides structural stability, allowing the composite insulator to maintain its electrical insulation function without undergoing creep or stress relaxation.
2Reliability
If the central tube is subjected to compressive force, then the conductive tube is subjected to tensile force, but the connection structure becomes more complex
Solution Approach 1:
The connecting assemblies merge multiple functions into single components: they simultaneously provide mechanical connection, force transmission, and sealing functions. The sealing rings are integrated into the connecting assemblies, which connect both the conductive tube and central tube while maintaining the prestress forces, thereby reducing the number of separate components needed.
Solution Approach 2:
The invention applies prestress parameters (compressive force on central tube, tensile force on conductive tube) during assembly to ensure proper sealing and mechanical connection. These parameter changes are maintained throughout the service life to prevent leakage and maintain connection integrity without requiring complex additional structures.
Data Source
AI summary
The present disclosure relates to a bushing and a manufacturing method therefor. The bushing includes a conductive tube and a central tube. The conductive tube is fixedly connected to a bottom connecting assembly and a top connecting assembly. The central tube is fixedly connected to the bottom connecting assembly and the top connecting assembly. The central tube is subjected to a compressive force in an extending direction of the central tube, such that the conductive tube is subjected to a tensile force in an extending direction of the conductive tube. The embodiments of the present disclosure can eliminate or reduce creep or stress relaxation of composites to ensure mechanical properties and sealing performance in a life cycle of the bushing.