Arc Chute Exhaust Grid Layout to Prevent Rear Arc Reformation
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Solution Overview
Problem
Existing arc extinguishing devices in miniature circuit breakers face inefficiencies in preventing the reformation of electric arcs behind the arc chute, leading to potential device damage and safety risks due to ionized air recombination.
Innovation Solution
An insulating rear plate with separate vertical portions and exhaust zones, each with vents facing spaces between splitter plates, is fixed at the back of the arc chute to redirect and recirculate exhaust air, preventing arc reformation by separating air flows and minimizing ionized air escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single exhaust opening is used at the back of the arc splitter stack, then the structure is simple, but ionized air can escape and cause arc reformation behind the arc chute
Solution Approach 1:
The exhaust opening is divided into multiple separate openings (first exhaust opening and second exhaust opening) positioned at different locations on the arc splitter stack. This segmentation prevents ionized air from escaping through a single point, thereby preventing arc reformation while maintaining structural simplicity through the use of basic geometric shapes.
Solution Approach 2:
The exhaust openings are positioned at different spatial locations (different dimensions) on the arc splitter stack - specifically, the first exhaust opening is at a first location and the second exhaust opening is at a second location. This dimensional distribution ensures that ionized air cannot escape and recombine to form arcs, solving the reliability issue without significantly increasing complexity.
2Productivity
If exhaust openings are positioned to face spaces between splitter plates, then ionized air evacuation is improved, but the risk of arc reformation increases
Solution Approach 1:
Multiple exhaust openings are distributed at different locations on the arc splitter stack, each facing different spaces between splitter plates. This segmentation allows ionized air to be evacuated efficiently through multiple paths while preventing concentration of ionized air that could lead to arc reformation.
Solution Approach 2:
Each exhaust opening is specifically positioned to face a particular space between splitter plates, creating localized evacuation paths. This local quality optimization ensures efficient ionized air removal from specific high-risk zones while the distributed arrangement prevents overall arc reformation.
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 arc reformation behind the arc chute, enhancing the arc extinguishing process and reducing external ignition risks by ensuring complete ionized air evacuation within the circuit breaker.
Implementation Method 1
Circuit breakers contain so-called arc chutes, a stack of mutually insulated parallel metal plates that divide and cool the arc, thus permitting the cooling and evacuation of the ionized air. By splitting the arc into smaller arcs, the arc is cooled down while the arc voltage is increased and serves as an additional impedance that limits the current through the circuit breaker.
Implementation Method 2
a rear plate is fixed at the rear of the arc splitter stack, the rear plate comprising openings to let the exhaust air flows outside the arc splitter stack. German patent DE 10 2009 056 190 discloses that a dividing wall divides the exhaust air flow of the arc-extinguishing gases emerging from the ventilation openings into a first and a second partial exhaust air flow, with the partial exhaust air flows running in opposite directions.
Implementation Method 3
Ionized air is evacuated through the arc chute and may then exit the miniature circuit breaker through ventilation openings (or exhaust vents).
Data Source
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AI summary
The invention concerns an arc extinguishing device for a circuit-breaker, comprising an arc splitter stack, the arc splitter stack comprising a plurality of extinguishing splitter plates stacked on top of each other and being kept apart from each other in the direction of stacking, the arc extinguishing device comprising an insulating rear plate being fixed at the back of the arc splitter stack, the insulation rear plate being subdivided into a first and a second vertical portions, each vertical portion comprising respectively a first and a second exhaust zone, each exhaust zone comprising one or more vents facing spaces between two adjacent extinguishing splitter plates, the first exhaust zone being located in an upper part of the first portion, the second exhaust zone being located in a lower part of the second portion.