Gas-Insulated Circuit Breaker Buffer Volume Design
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Solution Overview
Problem
Gas-insulated circuit breakers face challenges with late restrikes due to heated gas flowing back to the arcing zone, reducing the dielectric strength and increasing the likelihood of arc re-ignition, especially during long arcing times, which existing solutions like increasing heating or compression volumes are costly and difficult to implement.
Innovation Solution
A gas-insulated circuit breaker design featuring a nozzle with a diffuser portion and a buffer volume divided by a buffer dividing member with apertures, which directs arc-extinguishing gas efficiently away from the arcing region, reducing the likelihood of hot gas flow reversal and maintaining low-cost design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heating or compression volume is increased to reduce the risk of late restrikes, then the reliability against arc re-ignition is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The buffer volume is divided into multiple sub-volumes using buffer dividing members with apertures. This segmentation creates a multi-chamber structure that controls gas flow paths, preventing hot gas from returning to the arcing zone while maintaining a compact overall design. The divided structure achieves improved reliability without requiring a single large complex volume.
Solution Approach 2:
The buffer dividing members are positioned at specific locations within the buffer volume to create localized flow control. The apertures in the dividing members allow selective gas passage in certain regions while blocking hot gas return in critical areas near the arcing zone. This localized approach improves reliability targetedly without increasing overall device complexity.
2Reliability
If arc-extinguishing gas is blown to the arcing region during breaking operation, then arc extinction is achieved, but heated gas may flow back to the arcing zone causing late restrikes
Solution Approach 1:
The buffer volume and diffuser portion are designed to pre-establish a gas flow direction control system before hot gas can return to the arcing zone. The diffuser geometry and buffer volume create a preliminary barrier that guides gas flow away from the arcing region, preventing the harmful back-flow before it can occur. This preliminary anti-action maintains arc extinction capability while preventing late restrikes.
Solution Approach 2:
The buffer volume acts as an intermediary chamber between the arcing zone and the external environment. It receives the arc-extinguishing gas, allows it to cool and expand, and then directs it away from the arcing zone. This intermediary structure mediates the gas flow, preventing direct contact between hot gas and the arcing region while maintaining effective arc extinction.
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 effectively decreases the temperature of gas downstream from the arcing zone, reducing the risk of late restrikes and maintaining reliable arc extinction while preventing arc re-ignition, as demonstrated by computational fluid dynamics simulations.
Implementation Method 1
a nozzle (110) including a channel directed to the arcing region, for blowing an arc-extinguishing gas to the arcing region during the breaking operation
Implementation Method 2
a diffuser portion (114) adjacent to the nozzle, which serves for transporting the gas from the arcing region to a region downstream of the diffuser portion
Data Source
AI summary
The present disclosure provides a gas-insulated high or medium voltage circuit breaker including a first arcing contact and a second arcing contact, wherein at least one of the two arcing contacts is axially movable along a switching axis, wherein during a breaking operation, an arc between the first arcing contact and the second arcing contact is formed in an arcing region; a nozzle including a channel directed to the arcing region, for blowing an arc-extinguishing gas to the arcing region during the breaking operation; a diffuser portion adjacent to the nozzle, for transporting the gas from the arcing region to a region downstream of the diffuser portion; a buffer volume directly downstream of the diffuser portion; and an enclosure confined within a housing of the circuit breaker.