Self-Resetting Fuse With Transistor Current Limiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronic protection devices that rely solely on self-resetting thermal fuse elements face issues with premature aging and potential destruction due to continuous overloading, leading to increased risk of damage to connected components and limited control over tripping delay and ambient temperature influences.
Innovation Solution
An electronic protection device incorporating a thermally self-resetting fuse element connected in series with a transistor and a monitoring circuit that blocks the transistor when the current exceeds a predefined maximum value, allowing it to reset when the current falls below a predefined reset value, thereby extending the device's lifespan and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a self-resetting thermal fuse element is used to protect electrical components, then the device can automatically reset after a fault event without replacement, but the fuse element undergoes irreversible changes and premature aging during continuous operation in the tripped state, shortening its lifetime
Solution Approach 1:
A monitoring circuit is introduced as an intermediary between the power source and the fuse element. This circuit continuously monitors the current flowing through the fuse element and actively controls a series switch (transistor or thyristor) to interrupt the current when a maximum current value is exceeded, preventing the fuse element from undergoing continuous thermal stress and aging while maintaining the automatic reset capability.
2Reliability
If the fuse element is kept in the tripped state for extended periods due to undetected wiring errors, then protection is maintained, but the fuse element may be destroyed, leading to increased current that can damage connected components or cause fire hazards
Solution Approach 1:
The monitoring circuit implements a feedback mechanism by continuously measuring the current through the fuse element and comparing it with a predefined maximum current value. When the current exceeds this threshold, the monitoring circuit triggers the series switch to interrupt the current flow, and the switch remains interrupted until the current drops below a reset threshold, preventing catastrophic failure from extended tripped states.
Solution Approach 2:
The series switch is positioned upstream of the fuse element in the current path. By activating the switch to interrupt current flow before the fuse element can be continuously stressed, the system performs a preliminary protective action that prevents the fuse element from reaching a destroyed state, thereby eliminating the risk of fire hazards and component damage associated with fuse element destruction.
3Device complexity
If only a fuse element is used for overcurrent protection, then the device is simple in structure, but the tripping delay cannot be selectively influenced and is heavily dependent on fuse element manufacturer specifications
Solution Approach 1:
The monitoring circuit dynamically adjusts the current flow through the fuse element by controlling the series switch based on real-time current measurements. This dynamic control enables selective influence of tripping delay by adjusting the maximum current threshold and reset current threshold parameters in the monitoring circuit, providing adaptability while maintaining relatively simple device structure.
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 significantly extends the protection device's lifespan by preventing excessive current increases over extended periods, enhances reliability by reducing the risk of fire hazards, and allows for customizable tripping delay, thereby improving overall circuit reliability and reducing the risk of consequential damages.
Implementation Method 1
a fuse element, which is thermally self-resetting, and wherein the fuse element is provided and set up to conduct or limit a first current as a function of a fuse element temperature
Implementation Method 2
a monitoring circuit that influences the first transistor, wherein the monitoring circuit is provided and set up to block the first transistor, when the first current reaches or exceeds a predefined maximum current value, and to unblock it, when the first current reaches or falls below a predefined reset current value
Data Source
AI summary
An electronic protection device for protecting at least one electrical load, connectable to the protection device, whereby the electronic protection device has an input terminal and an output terminal, and whereby the protection device includes a fuse element, which is thermally self-resetting, and whereby the fuse element is provided and set up to conduct or limit a first current as a function of a fuse element temperature, whereby a limiting component is provided to limit the first current, and whereby the limiting component has a first transistor that is connected in series to the fuse element and a monitoring circuit that influences the first transistor. The monitoring circuit blocks the first transistor when the first current reaches or exceeds a predefined maximum current value and unblocks it when the first current reaches or falls below a predefined reset current value.