Residual Current Breaker Contact Force Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrical line protection devices of the differential circuit breaker type face challenges in withstanding high balanced short-circuit currents without internal damage, as existing solutions either increase the risk of thermal runaway or require significant ergonomic changes and increased arming force.
Innovation Solution
The device incorporates a flexible conductor connected to the movable contact at a distance from the pivot point, generating an additional contact force that counters electrodynamic repulsion forces, maintaining contact closure during high short-circuit currents without increasing the arming force, and using rivets made of silver-tin alloy for durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tungsten is used to form the pad of the moving contact to counter repulsion effects, then wear and sticking are reduced, but the risk of thermal runaway increases
Solution Approach 1:
The patent changes the material parameter from tungsten to copper, fundamentally altering thermal and electrical properties. Copper provides superior thermal conductivity to dissipate heat and prevent thermal runaway, while maintaining adequate mechanical strength for contact durability under short-circuit conditions.
Solution Approach 2:
The patent employs a composite structure where the moving contact pad is made of copper rather than tungsten, leveraging copper's composite properties of high electrical conductivity, high thermal conductivity, and sufficient mechanical strength to resolve the contradiction between contact durability and thermal runaway risk.
2Reliability
If a spring with higher force is used to increase contact force between fixed and moving contacts, then contact stability improves, but the arming force of the device increases
Solution Approach 1:
The patent implements a self-reinforcing mechanism where the electromagnetic force generated by short-circuit current automatically increases the contact force when needed. The system serves itself by using the problematic high current to generate the beneficial contact pressure, eliminating the need for a pre-configured high-force spring that would increase arming force.
Solution Approach 2:
The patent transitions from a static spring-based contact force system to a dynamic electromagnetic force system. The contact force becomes variable, automatically adjusting to match the instantaneous current level, providing high contact stability during short-circuits while maintaining low arming force during normal operation.
3Reliability
If the movable contact is connected to the fixed contact via a flexible conductor at a distance from the pivot point, then electrodynamic repulsion is counteracted, but the device complexity increases
Solution Approach 1:
The patent makes the flexible conductor serve multiple functions: it provides electrical connection between contacts, acts as a current path to generate electromagnetic force, and functions as a mechanical element to transmit force to the movable contact. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the electrical connection function and the force transmission function into a single flexible conductor element. By connecting the conductor at a distance from the pivot point, it simultaneously serves as the current path and the force application mechanism, consolidating multiple functions into one component.
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 effectively prevents contact separation during high short-circuit currents, reduces wear, and maintains device functionality by balancing electrodynamic forces, ensuring the device can handle currents up to ten times the nominal current without damage.
Implementation Method 1
generating an additional contact force that counters electrodynamic repulsion forces
Implementation Method 2
there is an imbalance of intensity detected by a torus
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A line protection electrical device, of the residual current circuit breaker type, comprising: - a switching device, - a tripping device capable of pivoting a lock of the switching device to open contacts (1, 2) in the event of a residual current short circuit, and capable of keeping the contacts (1, 2) closed in the event of a balanced short circuit current. In the closed position of the contacts (1, 2), said moving contact (1) is held against said fixed contact (2) by the action of an elastic means (5) inducing a nominal contact force applied to the fixed contact (2). This device is characterized in that it includes means for transforming the balanced short circuit current into an additional contact force, the sum of the forces being at least equal to the electrodynamic repulsive forces Fr of the contacts generated by the balanced short circuit current.