Molded Case Circuit Breaker Arc Extinguishing Grid Barrier
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Solution Overview
Problem
Mold cased circuit breakers face issues with debris from arc extinguishing not being effectively adhered to grids, leading to erroneous operations and reduced interruption capability due to debris spread within the circuit breaker.
Innovation Solution
The design includes a pair of side plates with at least one first grid and a second grid coupled to the upper ends of the side plates, featuring a bent portion with a preset angle, and a barrier that contacts the second grid, creating a larger space for arc extinguishing and preventing debris spread by positioning the second grid to block debris from entering the main body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grids are arranged in parallel within the arc-extinguishing unit to absorb and extinguish arc, then arc extinguishing capability is improved, but debris generated during separation is not entirely adhered on the grids and spreads into the main body affecting other components
Solution Approach 1:
A barrier is introduced as an intermediary component between the arc-extinguishing unit and the switching mechanism. This barrier prevents debris generated during arc extinguishing from spreading to the switching mechanism, while allowing the grids to continue their arc-absorbing function effectively.
Solution Approach 2:
The arc-extinguishing unit is segmented into distinct functional zones: the arc absorption zone with parallel grids, and the debris containment zone created by the barrier. This segmentation allows independent optimization of arc extinguishing and debris management functions.
2Reliability
If the interval between grid and movable contactor is increased to allow smooth arc extinguishing, then arc extinguishing performance is improved, but the space within the main body is reduced limiting the arc-extinguishing unit space
Solution Approach 1:
The barrier extends in the vertical dimension from the bottom base toward the top, creating additional containment space without increasing the horizontal footprint. This allows the arc-extinguishing unit to maintain adequate spacing for effective arc extinguishing while fitting within the limited main body volume.
3Reliability
If a barrier is added to prevent debris spread and improve interruption capability, then reliability is improved, but the device complexity increases
Solution Approach 1:
The barrier serves multiple functions simultaneously: it acts as a debris barrier preventing contamination of the switching mechanism, a structural support element for the arc-extinguishing unit, and a space-defining component that organizes the internal layout. This multi-functionality reduces the need for additional separate components.
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 configuration ensures that debris is adhered to the grids, reducing erroneous operations and improving the interruption capability of the circuit breaker by allowing a wider interval between the grid and the movable contactor, enabling smooth arc extinguishing and minimizing debris spread.
Implementation Method 1
segmenting and cooling the generated arc and discharging arc pressure to the outside
Implementation Method 2
a barrier defining a part of an outer wall of the accommodating part and protruding toward the arc-extinguishing unit
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A mold cased circuit breaker, which includes a casing, a switching unit disposed in the casing to open or close an electric circuit, and movable and stationary contractor units present within the casing, incudes an arc-extinguishing unit. The arc-extinguishing unit includes a pair of side plates facing each other with being spaced from each other, at least one first grid arranged between the side plates and spaced apart from one another with preset intervals, and a second grid coupled to upper ends of the side plates, spaced apart from the first grid, and having a bent portion with a preset angle.