Double-arranged Grid Structure for Arc Extinguishing in MCCBs
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Solution Overview
Problem
Molded case circuit breakers (MCCBs) face challenges in effectively extinguishing arcs during short circuits, leading to potential damage of grids and increased contact consumption, due to incomplete cooling and arc persistence, which affects their performance and reliability.
Innovation Solution
The implementation of a double-arranged grid structure in the extinguishing unit, where the first grids are inclined at a specific angle and the second grids are inclined at a greater angle, with cutout portions to facilitate arc division and cooling, creating an intermediate space for enhanced arc division and cooling, resulting in improved arc extinguishing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single arrangement of grids is used in the extinguishing part, then the device complexity is low, but the arc extinguishing performance is insufficient leading to incomplete cooling and arc persistence
Solution Approach 1:
The grid structure is segmented into two distinct arrangements: first grids with a first inclination angle and second grids with a second inclination angle. This segmentation allows each grid arrangement to perform a specific function in the arc extinguishing process, with the first grids initially cooling and dividing the arc, and the second grids further cooling and dividing the arc segments, thereby improving overall arc extinguishing performance without excessive complexity
Solution Approach 2:
The patent introduces a dimensional change by arranging grids at different inclination angles rather than using a single flat arrangement. The first grids are inclined at a first angle relative to the arc generation path, while the second grids are inclined at a second angle, creating a multi-dimensional grid structure that enhances arc cooling and division effectiveness from multiple angular perspectives
2Reliability
If grids are not sufficiently cooled, then the device complexity remains low, but the grids may be damaged or collapsed and contact consumption increases
Solution Approach 1:
The double-arranged grid structure performs preliminary cooling and division actions on the arc before it can cause significant damage. The first grids immediately cool and divide the arc upon generation, and the second grids further cool the divided arc segments, ensuring the arc is sufficiently cooled and extinguished before it can damage the grids or increase contact consumption
Solution Approach 2:
The patent provides beforehand cushioning by having two arrangements of grids that progressively cool and divide the arc. This dual-grid arrangement acts as a protective cushion that absorbs and dissipates arc energy through multiple cooling stages, preventing the arc from reaching temperatures that would damage the grids or cause excessive contact arm consumption
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 double-arranged grid structure effectively divides and cools the arc twice, enhancing arc extinguishing performance, reducing grid damage, and improving the overall reliability and efficiency of the MCCB.
Implementation Method 1
The arc is cooled by the grids 4b and divided into short arcs in between the grids 4b, whereby the arc voltage is increased and the current is reduced.
Implementation Method 2
an extinguish gas generated in the insulation plate (not shown) constituting the extinguishing part increases the internal pressure of the case, compresses the arc at a high pressure and suppresses release of free electrons, thereby quickly extinguishing the arc
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present disclosure relates to an extinguishing unit for a molded case circuit breaker, and more particularly, to an extinguishing unit for a molded case circuit breaker that has grids double-arranged in an extinguishing part to improve arc extinguishing performance. According to an embodiment of the present disclosure, an extinguishing unit for a molded case circuit breaker includes a pair of side plates arranged to face each other and a plurality of grids arranged in a space defined between the pair of side plates, wherein the grids include a plurality of first grids arranged at a front portion of the pair of side plates; and a plurality of second grids arranged at a rear portion of the pair of side plates, wherein a re-division space for re-dividing an arc is defined between the first grids and the second grids.