Circuit Breaker Parallel Contact Segmentation
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Solution Overview
Problem
Existing medium-voltage and high-voltage circuit breakers face limitations in current carrying capability and contact characteristics, particularly during short-circuits, due to excessive electromagnetic forces that can hinder the opening and closing movements.
Innovation Solution
A circuit breaker design featuring two contact arrangements with an arcing contact system and a rated current contact system connected in parallel, where inner rated current contacts overhang and are surrounded by outer rated current contacts, reducing electromagnetic forces and friction by splitting current flow and distributing contact pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If all rated current contact fingers are arranged coaxially at the same distance from the arcing contact, then the structural simplicity is maintained, but the current carrying capability and contact characteristics are limited during short-circuits due to excessive electromagnetic forces
Solution Approach 1:
The rated current contact system is segmented into inner rated current contacts and outer rated current contacts arranged at different radial distances from the arcing contact. This segmentation allows different contact groups to carry different portions of the current, distributing the electromagnetic forces and improving reliability during short-circuits while maintaining a relatively simple overall structure.
2Power
If the current flows through all rated current contact fingers simultaneously, then the current carrying capability is maximized, but the electromagnetic force exceeds the mechanical friction force and complicates or renders impossible the opening and closing movement
Solution Approach 1:
The inner rated current contacts are positioned to make contact before the outer rated current contacts during the closing movement. This preliminary action allows the inner contacts to establish the current path first, gradually building up current flow and electromagnetic forces in a controlled manner, preventing sudden excessive forces that would hinder movement, while still achieving maximum current carrying capability in the final closed state.
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 enhances the current carrying capability and improves contact functionality during switching operations, including short-circuits, by minimizing wear and friction forces, thus ensuring reliable operation without increasing switch volume.
Implementation Method 1
The pressure force is additionally reinforced by the electromagnetic force which occurs as a result of the current flow in the rated current contacts
Implementation Method 2
a body configured to be filled with a quenching gas
Data Source
AI summary
A circuit breaker is provided which can be filled with a quenching gas and which has two contact arrangements, which can be moved relative to one another and along a longitudinal axis of the circuit breaker. The contact arrangements form a arcing contact system and a rated current contact system connected electrically in parallel with it. One of the contact arrangements includes inner rated current contacts and outer rated current contacts of the rated current contact system, where the inner rated current contacts overhang the outer rated current contacts in the direction of the longitudinal axis, and the outer rated current contacts coaxially surround the inner rated current contacts. The circuit breaker has a high current carrying capability as well as a reliable switching-on and -off behavior, such as during and after the occurrence of a short-circuit current in the circuit breaker.