Electromechanical Circuit Breaker Auxiliary Contact Sequence
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Solution Overview
Problem
Circuit breakers face significant wear and limited make-and-break cycles when interrupting high currents, particularly at high voltages, due to arc development between switch contacts, leading to premature replacement and increased maintenance complexity.
Innovation Solution
An electromechanical circuit breaker design featuring a main contact pair with high electrical conductivity and an auxiliary contact pair made of a material with a higher melting point, where the auxiliary contacts open after and close before the main contacts, reducing contact damage and wear, and utilizing separate contact bridges to minimize erosion and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper or silver contacts are used for high current switching, then electrical conductivity is improved, but contact wear increases and make-and-break cycles are limited
Solution Approach 1:
The contact system is divided into two separate contact pairs: a main contact pair made of copper or silver for carrying high current during normal operation, and an auxiliary contact pair made of material with higher melting point for handling arc damage during switching. This segmentation allows each contact pair to be optimized for its specific function, resolving the contradiction between conductivity and durability.
Solution Approach 2:
The auxiliary contact pair acts as a sacrificial element that absorbs arc damage and wear during make-and-break cycles. Since these auxiliary contacts are designed to be replaced more easily, they protect the valuable main contacts from degradation, allowing the main contacts to maintain their conductivity without suffering from arc erosion.
2Reliability
If quenching gas or quenching magnets are added to extinguish arcs, then contact protection is improved, but device complexity increases
Solution Approach 1:
The patent extracts the arc-quenching function from external components (quenching gas or magnets) and integrates it directly into the contact structure itself. The auxiliary contact pair, positioned close to the main contacts, serves as an built-in arc shield that intercepts and extinguishes arcs without requiring separate quenching systems, thereby maintaining contact protection while minimizing structural complexity.
3Strength
If auxiliary contact pair is made of material with higher melting point, then resistance to arc damage is improved, but electrical conductivity decreases
Solution Approach 1:
Different parts of the contact system have different material properties optimized for their local function. The main contacts use highly conductive copper or silver for low-resistance current carrying during normal operation. The auxiliary contacts use materials with higher melting points like tungsten or molybdenum for arc resistance. Each location's material quality is tailored to its specific operational requirements, resolving the contradiction between conductivity and arc resistance.
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 safe interruption of high currents, reduces power losses, increases the number of make-and-break cycles, and extends the service life of the circuit breaker, lowering maintenance efforts by distributing the risk of damage to the more robust auxiliary contacts.
Implementation Method 1
arcs can develop during switching of the switch contacts and can result in wear of the switch contacts
Implementation Method 2
the auxiliary contact pair comprises a material that has a higher melting point than the main contacts
Data Source
AI summary
An electromechanical circuit breaker comprising a main contact pair comprising a first main contact disposed on a first main contact bridge; an auxiliary contact pair comprising a first auxiliary contact disposed on a first auxiliary contact bridge, the first auxiliary contact bridge being connected in parallel to the first main contact bridge and wherein the auxiliary contact pair comprises a material that has a higher melting point than a material of the main contact pair; a first armature configured to move the first main contact bridge; a second armature configured to move the first auxiliary contact bridge, wherein the first and second armatures are configured such that the auxiliary contact pair opens after the main contact pair opens, and the auxiliary contact pair closes before the main contact pair closes.