Switchgear Bushing Sealing via Compressed Rubber
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Solution Overview
Problem
Conventional bushing structures for switchgear are complex, difficult to assemble, and lack quality control, while also failing to effectively prevent gas intrusion during arc faults due to high arc pressures.
Innovation Solution
A bushing structure comprising separate support structures with openings and a compression structure made of rubber, which surrounds the bus receiving members to provide a sealed passage and improved assembly ease, using a single configuration for all current ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional multi-piece bushing structures are used, then the bus can be supported and passed through frames, but the assembly becomes difficult and tedious with poor quality control
Solution Approach 1:
The patent combines multiple separate bushing pieces into a single integrated molded bushing structure. The bushing is formed as one piece with multiple through-holes for bus bars, eliminating the need to assemble multiple components. This merging of parts directly resolves the assembly difficulty while maintaining the structural support function.
Solution Approach 2:
The single molded bushing structure serves multiple functions simultaneously: it supports multiple bus bars through its through-holes, provides electrical insulation, and seals the compartment. This multi-functional design eliminates the need for separate components for each function, simplifying the overall structure while improving ease of assembly.
2Reliability
If conventional bushing structures with putty or sealing material are used, then the bus can be sealed, but the assembly quality becomes difficult to control
Solution Approach 1:
The sealing function is merged into the bushing structure itself through integral sealing lips or flanges that are molded as part of the bushing. This eliminates the separate application of putty or sealing materials, ensuring consistent sealing quality without relying on manual assembly operations that are difficult to control.
Solution Approach 2:
The bushing structure provides its own sealing capability through integrated sealing features that automatically engage with the frame or other components during assembly. This self-sealing mechanism eliminates the need for additional sealing materials and operations, ensuring reliable sealing while simplifying the assembly process and improving quality control.
3Reliability
If porcelain bushings are used for high current ratings, then BIL and heat rise considerations are met, but the structure becomes more complex and assembly more difficult
Solution Approach 1:
The patent uses composite materials, specifically molded glass epoxy, that combine the electrical insulation properties, mechanical strength, and thermal resistance needed for high current applications. This composite material replaces traditional porcelain while maintaining the required BIL and heat rise performance, and simultaneously simplifies the structure by allowing single-piece molding rather than multi-assembly.
Solution Approach 2:
The invention changes the material parameter from porcelain to molded glass epoxy, which has comparable or superior electrical and thermal properties. This material substitution enables single-piece molding while meeting the BIL and heat rise requirements for high current ratings, thereby reducing structural complexity and assembly difficulty.
4Ease of manufacture
If arc gasses are allowed to leak into adjoining compartment, then the seal can be simpler, but gas intrusion into the next compartment must be prevented
Solution Approach 1:
The bushing structure incorporates segmented or multi-chambered sealing design with separate sealing lips or barriers for different compartments. This segmentation allows controlled leakage paths that prevent gas intrusion into protected compartments while maintaining simpler sealing construction compared to complete gas-tight barriers.
Solution Approach 2:
The bushing structure acts as an intermediary barrier between compartments, with integrated sealing features that manage arc gas flow. The sealing lips or flanges of the bushing create controlled pathways that allow limited leakage while blocking gas intrusion, simplifying the overall sealing system while providing adequate protection.
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 simplifies assembly, ensures a good seal against gas intrusion, and allows for consistent performance across various current ratings, while also providing shock and vibration resistance.
Implementation Method 1
the compression structure is disposed in the slot, sandwiched between the first and second support structures so that the first and second support structures exert pressure on the compression structure
Implementation Method 2
A bushing is constructed and arranged to be disposed in the passage. The bushing has a body, at least one bus receiving member, and a compression structure surrounding the at least one bus receiving member
Data Source
AI summary
A bushing structure for switchgear includes first and second separate support structures each having surfaces defining at least one opening. The support structures are coupled together so that the openings define a passage through the bushing structure and so that a slot is defined between the first and second support structures, surrounding the passage. A bushing is disposed in the passage and has a body, a bus receiving member, and a compression structure. The bus receiving member has an opening there-through sized to receive a bus bar. When the first and second support structures are coupled together with the bushing in the passage, the compression structure is disposed in the slot, sandwiched between the first and second support structures so that they exert pressure on the compression structure.