Bimetallic Strip Overload Detection with Measuring Toroid
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Solution Overview
Problem
Traditional thermal protection systems for electric lines, which use bimetallic strips, are prone to failure due to wet aging and external environmental factors like dust, leading to unreliable overload detection and potential device inoperability.
Innovation Solution
A system incorporating a measuring toroid and bypass loop with a bimetallic strip that forms a bypass loop during overloads, allowing the toroid to detect current differences and divert overload currents, while the actuator reacts to temperature increases without directly triggering the protection lock, thus maintaining thermal protection functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bimetallic strip is used for thermal protection in series with the electric line, then overload detection capability is provided, but the mechanical force required to trigger the protection lock increases over time due to wet aging and dust accumulation
Solution Approach 1:
The system divides the thermal protection function into two separate components: a bimetallic strip that detects overload conditions and a measuring toroid with bypass loop that executes the protection action. This segmentation isolates the bimetallic strip from the mechanical locking mechanism, preventing force degradation from affecting detection reliability.
Solution Approach 2:
The measuring toroid acts as an intermediary between the bimetallic strip and the protection lock. When the bimetallic strip detects an overload, it triggers the measuring toroid, which then activates the bypass loop to open the circuit. This intermediary mechanism eliminates the need for the bimetallic strip to directly overcome mechanical friction and aging effects.
2Reliability
If the bimetallic strip directly triggers the protection lock, then thermal protection is achieved, but the system becomes sensitive to environmental factors like dust and wet aging
Solution Approach 1:
The measuring toroid and bypass loop serve as an intermediary system that mediates between the bimetallic strip's detection function and the protection lock's mechanical function. This intermediary arrangement protects the bimetallic strip from direct exposure to harmful environmental factors during the triggering process.
Solution Approach 2:
The invention replaces the direct mechanical connection between the bimetallic strip and protection lock with an electromagnetic measurement system (toroid and bypass loop). This substitution reduces mechanical friction and contact wear, making the system less sensitive to dust and wet aging.
3Measurement precision
If the bimetallic strip is mounted in series in the electric line, then overload detection is enabled, but the mechanical force and energy required for triggering increase due to envelope creep and seizing
Solution Approach 1:
The system segments the protection mechanism into a detection component (bimetallic strip mounted in series for precise overload measurement) and an execution component (measuring toroid with bypass loop). This segmentation allows the bimetallic strip to focus on precise detection without bearing the full mechanical energy burden of triggering.
Solution Approach 2:
The measuring toroid acts as an energy-efficient intermediary that converts the bimetallic strip's detection signal into a magnetic field that activates the bypass loop. This intermediary mechanism requires significantly less mechanical energy than direct triggering, reducing the impact of envelope creep and seizing.
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
Enhances the reliability and durability of thermal protection by minimizing the mechanical force and energy required for overload detection, reducing the impact of aging and environmental degradation on the system's performance.
Implementation Method 1
a bimetallic strip mounted in series in the line to be protected
Implementation Method 2
deforms under the action of excessive heating resulting from the overload of current
Implementation Method 3
a measuring toroid designed to detect / measure directly or indirectly the bypass current of the bypass loop
Implementation Method 4
an actuator sensitive to an increase in current flowing through said electric line to connect, directly or indirectly, in the event of an overload, the bypass branch to the electric line
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to an overload detection system (10) on an electrical line (N, P) comprising at least one conductor, said system (10) comprising: a measurement torus (2), a current shunt branch (4) through which a shunt current can flow and which can be connected in parallel on the electrical line, an actuator (3) controlled in response to an increase in current passing through said electrical line (N, P) in order to connect, directly or indirectly, in the event of overload, the shunt branch (4) to the electrical line, characterised in that the shunt branch (4) and the electrical line form a shunt loop when the actuator is activated in the case of overload, and in that the measurement torus (2) is intended to directly or indirectly detect the shunt current of the shunt loop. The invention also relates to a electrical differential device (8) placed on an electrical line (N, P) and characterised in that it comprises such a detection system (10).