Bi-stable Trip Unit with Flux Transfer Reset
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Solution Overview
Problem
Existing circuit breakers face challenges in efficiently controlling tripping and releasing operations, particularly in maintaining a tripped position without external power and ensuring safe reset conditions, which can lead to unreliable circuit protection.
Innovation Solution
A bi-stable trip unit incorporating a movable armature and yoke with a magnetic flux transfer system, utilizing a permanent magnet and solenoids with ferromagnetic cores to generate attractive and repulsive forces, allowing for controlled tripping and resetting operations without continuous power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional trip unit is used without external power, then the device complexity is reduced, but the reliability of maintaining tripped position and controlling reset operations deteriorates
Solution Approach 1:
The patent replaces conventional mechanical spring-based trip units with an electromagnetic system using a permanent magnet and solenoid. The permanent magnet provides continuous holding force without external power, while the solenoid enables controlled tripping and resetting operations through electromagnetic force, resolving the contradiction between simplicity and reliability.
Solution Approach 2:
The solenoid is activated periodically or on-demand to generate electromagnetic force for tripping and resetting operations, rather than requiring continuous power supply. This periodic activation maintains reliability while minimizing energy consumption and system complexity.
2Reliability
If a permanent magnet and solenoid system is used, then the reliability of tripping and resetting operations is improved, but the device complexity increases
Solution Approach 1:
The patent combines the permanent magnet and solenoid into an integrated magnetic flux transfer system where the solenoid's ferromagnetic core works together with the permanent magnet. This merging reduces the number of separate components and simplifies the overall structure while maintaining reliable tripping and resetting control.
Solution Approach 2:
The solenoid serves multiple functions: generating electromagnetic force for tripping, assisting the permanent magnet in holding the tripped position, and enabling controlled resetting when energized in reverse. This multi-functionality reduces the need for separate mechanisms, offsetting the added complexity with functional consolidation.
3Reliability
If electromagnetic force is used to counter reset spring force, then the tripping operation reliability is improved, but the energy consumption increases
Solution Approach 1:
The solenoid is energized only temporarily during tripping and resetting operations rather than continuously. The permanent magnet provides continuous holding force without energy consumption, while the solenoid supplies electromagnetic force only when needed, significantly reducing overall energy consumption while maintaining tripping reliability.
Solution Approach 2:
The permanent magnet provides a continuous counteracting force that balances the reset spring force, reducing the energy burden on the solenoid. The solenoid only needs to provide additional electromagnetic force temporarily to overcome this balanced state for tripping, rather than continuously opposing the spring force, thereby reducing energy consumption.
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 solution enables reliable tripping and resetting of circuit breakers, ensuring safe and efficient interruption of current flow and resumption, even in the absence of external power, thereby enhancing circuit protection and operational reliability.
Implementation Method 1
The magnetic flux transfer system is configured to generate an attractive force using a solenoid from the one or more solenoids to counter the force of the reset spring and latch friction force when a tripping condition is detected
Implementation Method 2
one or more solenoids with a ferromagnetic core to generate attractive and repulsive forces
Implementation Method 3
one or more solenoids each with a ferromagnetic core
Data Source
AI summary
A trip unit for a circuit breaker includes a magnetic flux transfer system that employs a permanent magnet(s) and solenoid(s) with a ferromagnetic core. The system generates an attractive force using a solenoid to counter the force of a reset spring and latch friction force when a tripping condition is detected. The generated attractive force together with an attractive force from the magnet attracts a yoke which in turn moves the yoke together with an armature to the tripped position. The system also retains the yoke and armature in the tripped position using the attractive force of the magnet when the generated attractive force is no longer being generated. The system further generates a repulsive force using a solenoid when a resettable condition is satisfied to counter the attractive force of the magnet thereby allowing the yoke and armature to move from the tripped position to the reset position.