Medium-Voltage Switching Pole with Bistable Vacuum Interrupter
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Solution Overview
Problem
Existing load-break switches for medium voltage electric systems face challenges in achieving high-level performances in dielectric insulation and arc-quenching capabilities while maintaining structural compactness, reliability, and environmental sustainability, particularly due to the limitations of using alternative insulation gases after the phase-out of SF6.
Innovation Solution
The switching apparatus incorporates a vacuum interrupter with a bistable motion transmission mechanism, featuring a first and second lever configuration that allows the movable arc contact to transition between coupled and uncoupled positions within a vacuum chamber, ensuring efficient arc quenching and synchronization with the movable contact's movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If alternative insulation gases (pressurized dry air or environment-friendly mixtures) are used instead of SF6, then environmental impact is reduced, but arc-quenching capabilities and dielectric insulation performances deteriorate
Solution Approach 1:
The patent employs a vacuum interrupter that creates a vacuum environment (pressure less than 10^-3 Pa) within the vacuum chamber. This vacuum atmosphere provides superior dielectric insulation properties and arc-quenching capabilities compared to alternative gases, while the external pressurized dry air or environment-friendly gas mixture maintains environmental sustainability. The vacuum environment effectively eliminates the harmful effects associated with SF6 while preserving excellent electrical performance.
2Reliability
If multiple contact arrangements (air atmosphere contacts and vacuum atmosphere contacts) are used for each electric pole, then arc-quenching capabilities are improved, but device complexity and structural compactness deteriorate
Solution Approach 1:
The patent merges the functions of current carrying and arc quenching into a single integrated contact arrangement within the vacuum interrupter. The movable contact and fixed contacts are designed to perform both current conduction and arc extinction functions simultaneously in the vacuum environment, eliminating the need for separate air atmosphere contacts and vacuum contacts. This integration significantly reduces device complexity while maintaining high-level arc-quenching capabilities.
Solution Approach 2:
The contacts within the vacuum interrupter are designed with multi-functionality, serving both as current-carrying elements and as arc-quenching elements. The same movable contact and fixed contacts that conduct normal operating currents also serve as the arc paths during switching operations, eliminating the need for dedicated arc-quenching contacts separate from the main current path.
3Reliability
If multiple contact arrangements with different atmospheres are used, then arc-quenching capabilities are improved, but manufacturing complexity and production costs increase
Solution Approach 1:
The patent combines all necessary contact arrangements and atmospheric environments into a single vacuum interrupter unit. This integration simplifies manufacturing by requiring only one vacuum chamber fabrication process, one set of contact assembly procedures, and a single sealing system, rather than requiring separate manufacturing processes for multiple air and vacuum contact arrangements.
Solution Approach 2:
The vacuum environment within the vacuum interrupter provides a universally applicable medium for both current conduction and arc quenching across all phases and operating conditions. This eliminates the need to manufacture and assemble different types of contacts for different atmospheric conditions, significantly reducing manufacturing complexity and production costs while maintaining superior arc-quenching performance.
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 solution achieves high-level performances in dielectric insulation and arc-quenching capabilities, enhances structural compactness and reliability, and facilitates easy industrial-scale manufacturing at competitive costs, while minimizing environmental impact.
Implementation Method 1
a vacuum interrupter, which comprises a fixed arc contact electrically connected to the first pole terminal and a movable arc contact reversibly movable along a corresponding translation axis between a coupled position with the fixed arc contact and an uncoupled position from the fixed arc contact. The vacuum interrupter also comprises a vacuum chamber, in which the fixed arc contact and the movable arc contact are enclosed and can be coupled or separated.
Implementation Method 2
Most traditional load-break switches of the state of the art have their electric poles immersed in a sulphur hexafluoride (SF6) atmosphere as this insulating gas ensures excellent performances in terms of dielectric insulation between live parts
Data Source
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AI summary
A switching apparatus comprising one or more electric poles. For each electric pole, the switching apparatus comprises a first pole terminal, a second pole terminal and a ground terminal. In operation, the first pole terminal can be electrically coupled to a first conductor of an electric line, the second pole terminal can be electrically coupled to a second conductor of said electric line and the ground terminal can be electrically coupled to a grounding conductor. For each electric pole, the switching apparatus comprises a plurality of fixed contacts spaced apart one from another. Such a plurality of fixed contacts comprises a first fixed contact electrically connected to the first pole terminal, a second fixed contact electrically connected to the second pole terminal, a third fixed contact electrically connected to the ground terminal. For each electric pole, the switching apparatus comprises a movable contact, which is reversibly movable about a corresponding rotation axis according to opposite first and second rotation directions, so that said movable contact can be coupled to or uncoupled from one or more of the above-mentioned fixed contacts. For each electric pole, the switching apparatus comprises a vacuum interrupter comprising a vacuum chamber, in which a fixed arc contact and a movable arc contact are enclosed and can be coupled or separated. For each electric pole, the switching apparatus comprises a motion transmission mechanism operatively coupled to the movable arc contact of said vacuum interrupter. The motion transmission mechanism is actuatable by the movable contact to cause a movement of said movable arc contact along said translation axis, when said movable contact moves about said rotation axis.