Arc Chute Protection Elements for Circuit Breaker Erosion
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Solution Overview
Problem
Circuit breakers with air-breaking chambers face premature wear and reliability issues when subjected to repeated high-current electric arcs, particularly at low voltages and high currents, due to prolonged arc duration at the junctions between separation plates and vertical walls, leading to erosion and potential failure.
Innovation Solution
Incorporating cross-linked polyamide protection elements with a concave shape along the side walls of the arc chute, which guide the electric arc away from the side walls and prevent damage, while being devoid of glass fibers to avoid conductive metal redeposition and dielectric breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional polyamide fabric impregnated with thermosetting resin and glass fibres is used for side walls, then structural strength is improved, but reliability deteriorates due to prolonged arc duration causing erosion and premature wear
Solution Approach 1:
The side wall structure is segmented into two functional parts: the main structural body made of polyamide fabric impregnated with thermosetting resin and glass fibres for strength, and separate protection elements made of cross-linked polyamide without glass fibres positioned at critical junction areas. This segmentation allows each part to optimize its specific function without compromising the other.
Solution Approach 2:
Protection elements made of cross-linked polyamide serve as intermediary components between the electrical contacts and the main side wall structure. These intermediaries absorb and redirect the electric arc away from the junction areas where the separation plates meet the side walls, preventing direct erosion of the main structural material.
2Ease of manufacture
If glass fibres are included in the polyamide fabric, then manufacturing ease is improved, but object-generated harmful factors worsen due to conductive metal redeposition causing dielectric breakdown
Solution Approach 1:
Different regions of the arc chute have different material compositions tailored to their specific functional requirements. The main side walls use polyamide fabric with glass fibres and thermosetting resin for structural integrity and ease of manufacture. The protection elements at critical junction areas use cross-linked polyamide without glass fibres to prevent conductive metal redeposition and dielectric breakdown.
Solution Approach 2:
The invention employs composite materials with different compositions in different locations: the main side walls use a composite of polyamide fabric, glass fibres, and thermosetting resin, while the protection elements use a different composite of cross-linked polyamide without glass fibres. This allows optimization of both manufacturing ease and prevention of harmful effects in their respective locations.
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 enhances the durability and resistance to wear of the arc chute, reducing erosion and improving the reliability of the circuit breaker by effectively managing electric arcs and extending the lifespan of the interrupting chamber.
Implementation Method 1
an electric arc breaking chamber, for extinguishing an electric arc formed during the separation of the electrical contacts
Implementation Method 2
comprise metal separation plates stacked horizontally at a distance from each other, which make it possible to split the electric arc and to absorb part of its energy, thus contributing to its extinction
Implementation Method 3
an electric arc can form between these two electrical contacts. In the case of circuit breakers with air breaking, this electric arc ionizes the ambient air present in the circuit breaker, which generates gases, called breaking gases
Data Source
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AI summary
This air-break circuit breaker comprises: - two separable electrical contacts connected to input and output terminals for an electric current; - an arc-breaking chamber (18) comprising a stack (20) of spaced separating plates (22) and side walls (24) arranged on either side of the stack (20) and made of polyamide fabric impregnated with thermosetting resin and free of glass fibers. The breaking chamber (18) further comprises protective elements (40) made of cross-linked polyamide positioned at the junction zones between the side walls (24) and the retaining plates (22), the protective elements (40) covering corners (49) of the separating plates (22) adjacent to the side walls (24), so as to separate these corners (49) from the separating plates (22) and the electrical contacts.