Magnetic DC Trip Assembly for Circuit Breaker Over-Current Detection
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Solution Overview
Problem
Circuit breakers designed to detect over-current conditions in AC currents cannot detect DC over-current conditions, necessitating a DC trip assembly that can replace AC trip assemblies and be integrated into existing AC-only circuit breakers.
Innovation Solution
A magnetic DC trip assembly is introduced, comprising a magnet and armature assembly with a pivotal coupling, biasing assembly, and calibration assembly, which moves between positions to detect and respond to DC over-current conditions by interacting with the trip bar linkage and operating mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an AC trip assembly is used in a circuit breaker, then the circuit breaker can detect AC over-current conditions, but it cannot detect DC over-current conditions
Solution Approach 1:
The trip assembly is designed to perform multiple functions by incorporating both AC trip mechanisms and DC trip mechanisms within a single unified structure. The AC trip assembly includes thermal and magnetic elements responsive to AC current, while the DC trip assembly includes similar elements responsive to DC current. This multi-functional design allows the same trip assembly to detect and respond to both AC and DC over-current conditions, eliminating the need for separate trip assemblies for different current types.
2Reliability
If a DC trip assembly is designed to replace an AC trip assembly in existing circuit breakers, then DC over-current detection is enabled, but the device complexity increases
Solution Approach 1:
The patent merges the AC trip assembly and DC trip assembly into a single integrated unit. Both trip mechanisms share common structural elements including the housing, mounting provisions, and linkage to the trip-free latch. The AC trip elements and DC trip elements are positioned adjacent to each other within the same housing and both connect to the same trip bar. This consolidation reduces the overall complexity compared to having separate trip assemblies while maintaining the ability to detect both AC and DC over-current conditions.
Solution Approach 2:
The trip assembly is designed to perform multiple functions by incorporating both AC trip mechanisms and DC trip mechanisms within a single unified structure. The AC trip assembly includes thermal and magnetic elements responsive to AC current, while the DC trip assembly includes similar elements responsive to DC current. This multi-functional design allows the same trip assembly to detect and respond to both AC and DC over-current conditions, eliminating the need for separate trip assemblies for different current types.
3Adaptability or versatility
If a trip assembly is designed to work with both AC and DC currents, then versatility is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The trip assembly employs local quality by providing separate optimized trip mechanisms for AC and DC currents within the same housing. The AC trip elements are positioned and dimensioned specifically for AC current response, while the DC trip elements are positioned and dimensioned specifically for DC current response. Each local section of the trip assembly is optimized for its specific current type, allowing both to coexist without requiring the entire assembly to meet the most stringent precision requirements of either current type alone.
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 magnetic DC trip assembly effectively replaces AC trip assemblies, enabling detection and response to DC over-current conditions within existing circuit breakers, ensuring safe operation by moving contacts to the open position during over-current events.
Implementation Method 1
The armature assembly body is structured to move between a first position, wherein the armature assembly body is close to the magnet, and a second position, wherein the armature assembly body is spaced from the magnet
Data Source
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AI summary
A D/C trip assembly (50) for a circuit breaker (10) is provided. The D/C trip assembly (50) includes a magnet (30), a mounting assembly(52) and an armature assembly (54). The mounting assembly (52) includes a body (60), the mounting assembly body (60) including a pivotal coupling (62). The armature assembly (54) includes a magnetic body (110) and a trip bar linkage (130), the trip bar linkage (130) extending from the armature assembly body (110). The armature assembly body (110) is structured to move between a first position, wherein the armature assembly body (110) is close to the magnet (30), and a second position, wherein the armature assembly body (110) is spaced from the magnet (30). The trip bar linkage (130) is structured to move between a first position and a second position, the trip bar linkage (130) positions corresponding to the armature assembly body (110) positions. The trip bar linkage (130) is structured to be coupled to a trip bar (42).