Electronic Bimetallic Strip Emulator for Thermal Protection
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Solution Overview
Problem
Current thermal protection devices for electric lines, such as bimetallic circuit breakers, are not very precise and have a limited lifespan, requiring frequent replacements and manual intervention, and are not effective in accurately disconnecting power lines during overheating events.
Innovation Solution
A bimetallic strip emulation device that uses a current sensor to measure line current, calculates a cumulative thermal state over time, and includes a squaring operator to determine the thermal state, allowing for precise disconnection of power lines when the thermal state exceeds a target value, thereby extending the device's lifespan and enabling remote operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bimetallic strip is used in a thermal circuit breaker, then the device can automatically disconnect the line when excessive current flows, but the device has a limited lifespan (less than 4000 operations) and requires manual intervention for resetting
Solution Approach 1:
The patent replaces the mechanical bimetallic strip system with an electronic emulation device that uses a microprocessor to calculate thermal state based on measured current. This substitution eliminates the mechanical wear limitations of the bimetallic strip while maintaining the thermal protection function, thereby extending the device lifespan beyond 4000 operations.
Solution Approach 2:
The patent creates a functional copy of the bimetallic strip's thermal response characteristics using digital calculation. The microprocessor emulates the thermal accumulation and dissipation behavior through mathematical models, reproducing the protective function without the physical limitations of the original mechanical system.
2Reliability
If a bimetallic strip is used in a thermal circuit breaker, then the device provides thermal protection, but the precision of disconnection is not very accurate
Solution Approach 1:
The patent replaces the mechanical bimetallic strip with an electronic system that uses a current sensor and microprocessor to precisely measure and calculate thermal state. This substitution enables accurate measurement of current and thermal parameters, achieving precise disconnection control that overcomes the imprecision of mechanical bimetallic systems.
Solution Approach 2:
The patent implements a feedback mechanism where the microprocessor continuously monitors current through a sensor, calculates the thermal state based on accumulated data, and adjusts the disconnection decision accordingly. This closed-loop control enables precise thermal state measurement and accurate protection timing.
3Reliability
If a fuse is used to protect against overcurrent, then the line can be disconnected when current exceeds a given intensity, but the fuse requires replacement after each operation and provides imprecise protection
Solution Approach 1:
The patent replaces the disposable fuse with a reusable electronic protection device. The microprocessor-based system can be reset and reused after tripping, eliminating the need for replacement and reducing maintenance complexity while maintaining reliable overcurrent protection.
Solution Approach 2:
The patent enables recovery and reuse of the protection device after it has performed its protective function. Unlike a fuse that must be discarded, the electronic system can be reset and continues to provide protection, reducing waste and maintenance requirements.
4Reliability
If a thermal circuit breaker with bimetallic strip is used, then the line can be protected from overheating, but the device cannot be reset remotely and requires manual intervention
Solution Approach 1:
The patent replaces the manual reset mechanism of the bimetallic circuit breaker with an electronic reset system controlled by a microprocessor. This enables remote resetting capability through electronic control signals, eliminating the need for manual intervention and improving operational convenience.
Solution Approach 2:
The patent enables the protection device to perform self-resetting functions through automated control. The microprocessor can automatically reset the system after a protective trip under certain conditions, or respond to remote reset commands, reducing the need for manual service intervention.
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 provides improved precision and extended lifespan of the thermal protection device, allowing for accurate disconnection of power lines during overheating events, reducing the need for frequent replacements and enabling remote operation, thus enhancing safety and efficiency in thermal management.
Implementation Method 1
a current sensor able to measure a line current flowing through the emulation device
Implementation Method 2
When an excessive current crosses the bimetallic strip, the latter is deformed by the Joule effect mechanically causing the opening of the line
Data Source
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AI summary
The invention relates to a device (EMU) for emulating a bimetallic strip, the emulating device (EMU) comprising a current sensor (CC) able to measure a line current (I P ) flowing through the emulating device (EMU), the emulating device (EMU) being able to deliver a value representative of a time-cumulative thermal state (Eth_n) reached at the time t, which value is called the cumulative thermal state (Eth_n), by recurrently adding a value representative of an initial thermal state (Eth_i), which value is called the initial thermal state (Eth_i), and a value representative of a current thermal state (Eth_on, Eth_off), which value is called the current thermal state (Eth_on, Eth_off), said state being determined depending on the line current (I P ).