Switchgear Duct Jointing via Bent Ends and Bolted Seals
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Solution Overview
Problem
Conventional switchgear designs face challenges in ensuring airtightness of the discharge path for high-temperature high-pressure gas during arc faults or internal short-circuit faults, particularly at connection points between ducts, leading to potential leaks and reduced reliability.
Innovation Solution
The design incorporates a switchgear configuration with bent duct ends forming joining portions that are fastened using multiple pairs of fastening members, ensuring airtight contact between the common duct and the exhaust duct, and between duct plates, to prevent gas leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If general bolt connection is used between ducts, then ease of manufacture is improved, but airtightness cannot be ensured due to gaps formed between plate and bolt
Solution Approach 1:
The connection structure is divided into multiple components: a plate with an insertion hole, a insertion portion with a bent end forming a joining portion, and fastening members. This segmentation allows the bent end to form a tight-fitting joining portion that eliminates gaps while maintaining ease of assembly through modular components.
Solution Approach 2:
The end of the insertion portion is bent to form a curved joining portion that fits into the plate's insertion hole. This curvature creates a tight interference fit that eliminates gaps between connection surfaces, ensuring airtightness while allowing simple fastening with bolts or other fastening members.
2Reliability
If bellows structure passage is pushed and expanded to ensure discharge path, then airtightness is improved, but strength reduction due to deformation occurs
Solution Approach 1:
The joining portion is pre-formed by bending the end of the insertion portion before assembly. This preliminary action creates a ready-to-fit structure that ensures airtightness upon assembly without requiring deformation during operation, thereby maintaining the structural strength of the bellows passage.
3Reliability
If multiple fastening members are used to ensure airtightness at connection portions, then airtightness is improved, but device complexity increases
Solution Approach 1:
The bent end forming a curved joining portion creates inherent mechanical interference that ensures airtightness through the shape itself. This geometric feature works in conjunction with fastening members to seal the connection, reducing reliance on the number of fastening members while maintaining reliability.
Data Source
AI summary
At a connection portion between a common duct penetrating in an arrangement direction through switchgears arranged in the arrangement direction inside an electrical room, and an exhaust duct via which the common duct and outside of the electrical room communicate with each other, an end of the common duct is bent inward to form a first exhaust duct joining portion, and an end of the exhaust duct is bent outward to form a common duct joining portion. In a state in which an outer surface of the first exhaust duct joining portion and an inner surface of the common duct joining portion are in contact with each other, the first exhaust duct joining portion and the common duct joining portion are fastened and fixed by two or more pairs of bolts and welding nuts.