Vacuum Circuit Breaker Bushing Structure for Bellows Pressure Balance
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Solution Overview
Problem
Existing vacuum circuit breakers with filters in the movable-side frame and bushing terminal cannot completely prevent the ingress of water droplets, leading to potential damage to the bellows due to pressure differences.
Innovation Solution
A vacuum circuit breaker design featuring a tubular grounded tank with an insulating gas, a vacuum valve, and a movable-side bushing conductor with no vent holes, combined with a slider and packing mechanism to maintain atmospheric pressure and prevent water ingress, ensuring the bellows is not damaged by pressure differences during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air vent portions with filters are provided in the movable-side support plate and movable-side bushing terminal, then atmospheric air pressure is maintained in the movable-side frame, but water droplets can still ingress into the grounded tank
Solution Approach 1:
The invention removes the air vent portions entirely from the movable-side support plate and movable-side bushing terminal. By eliminating these openings, the patent prevents water droplet ingress while maintaining atmospheric pressure through an alternative mechanism - the communication between the movable-side frame interior and the external atmosphere via the movable conductor passage and operation rod passage, without requiring vent holes in critical components.
Solution Approach 2:
The patent introduces filters as intermediary components in the movable-side bushing conductor and operation rod passage, rather than in the air vent portions. These filters allow atmospheric pressure maintenance while blocking water droplets, serving as a mediating solution between the need for pressure equalization and water protection.
2Adaptability or versatility
If the bellows is made with an expansible tubular construction, then it can accommodate movement of the movable conductor, but it has low strength and may be damaged by pressure difference
Solution Approach 1:
The patent equalizes the pressure potential inside and outside the bellows by maintaining atmospheric air pressure in the movable-side frame through communication passages. This eliminates the pressure difference that would otherwise damage the bellows, allowing the expansible construction to function without compromising strength.
3Object-affected harmful factors
If filters are installed in air vent portions of movable-side support plate and movable-side bushing terminal, then water droplet ingress is restrained, but water droplets cannot be completely prevented from entering
Solution Approach 1:
The invention removes the air vent portions from the movable-side support plate and movable-side bushing terminal where they cannot provide adequate protection. By eliminating these openings entirely and replacing them with filter-equipped passages in different locations (movable-side bushing conductor and operation rod passage), the system achieves complete water droplet prevention while maintaining atmospheric pressure.
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
Effectively prevents water droplets from entering the grounded tank and maintains stable pressure within the bellows, thereby protecting it from damage during both closing and interrupting operations.
Implementation Method 1
a packing set in the hole to close a gap between the operation rod and the movable-side support plate in a watertight state
Implementation Method 2
a slider movably disposed inside the movable-side bushing conductor... to maintain atmospheric pressure and prevent water ingress, ensuring the bellows is not damaged by pressure differences
Implementation Method 3
a grounded tank in which an insulating gas is encapsulated
Implementation Method 4
a vacuum container in which the movable contact and stationary contact are housed
Data Source
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AI summary
A vacuum circuit breaker (50) includes: a grounded tank (1); a vacuum valve (2) including a vacuum container (2c) housing a movable contact (2a) and a stationary contact (2b), a movable conductor (7) that is connected to the movable contact (2a) and extends out of the vacuum container (2c), and a tubular bellows (3); a tubular movable-side bushing conductor (12a); a slider (40) movably set inside the movable-side bushing conductor (12a); a movable-side frame (5) that communicates with a space inside a tube of the bellows (3) and electrically connects the movable-side bushing conductor (12a) to the movable conductor (7); an operation rod (31) having one end (31a) protruding to an outside of the grounded tank (1) and an opposite end (31b) connected to the movable conductor (7); an operating device (30) that moves the operation rod (31); a movable-side support plate (8a) covering an end of the grounded tank (1) where the operation rod (31) extends out of the grounded tank (1); and a packing (33) set in a hole (32) .