Removable-Core Moving Conductor for Faster Circuit Breaker Opening
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Solution Overview
Problem
Movable contact assemblies in circuit interrupters face challenges in achieving ultra-fast opening speeds due to the significant force required to move the mass of the contact assembly, which affects the efficacy of hybrid circuit interrupters in minimizing arcing during fault conditions.
Innovation Solution
The use of a hollow outer stem made from annealed copper, with a removable core structure that includes a braze-compatible metal core for structural reinforcement during brazing and an ultra-lightweight aluminum core for operation, allowing for faster opening speeds by reducing the overall mass of the moving conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solid metal core is used in the moving conductor for structural strength, then the yield strength increases, but the opening speed decreases due to increased mass
Solution Approach 1:
The moving conductor is segmented into two functional parts: an outer shell providing structural integrity and an inner removable core providing mass reduction. This segmentation allows each part to be optimized independently - the outer shell maintains strength while the removable core minimizes mass to enable ultra-fast opening speeds.
Solution Approach 2:
The density parameter of the core material is changed from conventional metal to ultra-lightweight material (such as aerogel or foam), reducing the core density by factors of 1000x or more while maintaining the same core volume, thereby dramatically reducing the overall mass of the moving conductor.
2Speed
If an ultra-lightweight core is used in the moving conductor, then the opening speed increases, but the structural reinforcement during brazing is insufficient
Solution Approach 1:
The core material dynamically changes based on operational requirements: a dense metal core is used during the brazing process to provide structural reinforcement, and then it is replaced with an ultra-lightweight core for normal operation to enable fast opening speeds. This dynamic adaptation resolves the contradiction between strength during manufacturing and speed during operation.
Solution Approach 2:
The outer shell is pre-formed with brazing features and structural geometry before the final lightweight core is inserted. This preliminary action allows the shell to be strengthened through brazing with the temporary metal core in place, ensuring structural integrity is established before the weight-reducing core is installed.
3Adaptability or versatility
If the core is made removable and interchangeable, then the adaptability increases, but the device complexity increases
Solution Approach 1:
The outer shell design is made universal to accommodate multiple core types (different materials, densities, and configurations) through standardized insertion interfaces. This universality allows the same shell to work with various cores for different applications, increasing adaptability without proportionally increasing complexity.
Solution Approach 2:
The core is extracted as a separate, removable component from the moving conductor assembly, allowing it to be easily swapped without affecting the outer shell or other components. This extraction simplifies the interchangeability process and reduces the complexity of the overall system by making the core a standalone module.
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 design enables the moving conductor to open at significantly faster speeds, reducing arcing and enhancing the durability of the moving conductor, with a 25% reduction in weight and a ten-fold increase in yield strength, facilitating faster commutation of current and improved fault protection.
Implementation Method 1
the force required to open mechanical separable contacts quickly can be significant due to the mass of the movable contact assembly that must be moved
Implementation Method 2
a first removable core being produced from braze-compatible metal for insertion within the outer stem during production of the outer stem
Data Source
AI summary
An ultra-fast moving conductor for use with a circuit breaker is provided. The moving conductor includes a hollow outer stem and a removable core. Multiple removable cores are produced for use with the moving conductor for different purposes. The outer stem is produced from annealed copper that must be brazed before the circuit breaker is placed into operation, and a first removable core produced from copper is inserted into the outer stem to provide structural reinforcement to the outer stem during brazing. After brazing is complete, the copper core is removed from the outer stem, and a significantly lighter work hardened aluminum core is inserted into the outer stem. The lightweight aluminum core enables the moving conductor to open the circuit breaker much faster than the copper core would, and the copper core prevents contamination of the brazing furnace that would result from using the aluminum core during brazing.