Circuit Breaker Armature Offset for Arc Splatter Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing circuit breaker trip mechanisms, particularly those involving bimetal and magnetic armatures, face issues with arc splatter causing tack welding, which can lead to mechanical failure and unreliable operation.
Innovation Solution
Incorporating an offset structure between the bimetal and magnetic armature, such as a depressed pocket, slot, or projections, to prevent direct contact and potential welding during arc splatter events, ensuring the armature can pivot and trip the circuit breaker effectively without becoming stuck.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the armature window is positioned close to the bimetal for compact design, then device complexity is reduced, but arc splatter can enter the window and cause tack welding between the armature and bimetal
Solution Approach 1:
A non-conductive barrier element is introduced as an intermediary component between the armature window and the bimetal. This barrier prevents direct contact between molten arc splatter and the bimetal surface, eliminating the tack welding problem while allowing the armature window to remain in its effective position for compact design
Solution Approach 2:
The harmful factor (molten metal from arc splatter) is extracted or removed from the interaction path between the armature and bimetal by positioning the offset such that the window does not contact the bimetal surface, preventing the welding phenomenon
2Productivity
If the armature is positioned to engage the bimetal directly for effective tripping, then tripping effectiveness is improved, but the armature can become tack welded to the bimetal due to arc splatter
Solution Approach 1:
The offset positioning creates a non-conductive barrier that mediates between the armature and bimetal, allowing mechanical engagement for effective tripping while preventing direct contact that would cause tack welding from arc splatter
3Ease of operation
If the armature window is positioned to engage the cradle latch surface, then latching function is achieved, but the window fills with molten metal from arc splatter causing tack welding
Solution Approach 1:
The offset positioning of the armature window creates a protective barrier that prevents molten arc splatter from reaching the bimetal and filling the window, while maintaining the window's engagement with the cradle latch surface for proper latching function
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 offset structure prevents tack welding, allowing the armature to function reliably by maintaining clearance and ensuring proper tripping of the circuit breaker even under conditions of arc splatter, enhancing operational reliability and durability.
Implementation Method 1
When the circuit breaker is closed, a persistent overload current of a predetermined value causes the bimetal to become heated and deflect away from the cradle
Implementation Method 2
Flow of overload current above the higher predetermined value through a bimetal induces magnetic flux around such bimetal. This flux is concentrated by a magnetic yoke toward an armature
Implementation Method 3
An overload current above the higher predetermined value generates a magnetic force of such a strength that the armature is attracted toward the magnetic yoke
Data Source
AI summary
A trip mechanism includes a bimetal having a first side and an opposite second side, a magnetic yoke disposed proximate the first side of the bimetal, and a magnetic armature pivotally connected to the bimetal and disposed proximate the opposite second side thereof. The armature has a first side with a surface, an opposite second side, and an opening extending from the first side to the opposite second side of the magnetic armature. The opening has a latch surface structured to engage the latch surface of an operating mechanism. The first side of the magnetic armature is structured to engage the opposite second side of the bimetal. At least one of the bimetal and the magnetic armature is structured to provide an offset between the bimetal and the surface of the first side of the magnetic armature at the opening of the magnetic armature.