Fuse Cartridge With Resistive Element For Inrush Current Limiting
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Solution Overview
Problem
Existing fuse cartridges face issues with high inrush currents during circuit closure, particularly in direct current circuits with converter inverters and capacitors, leading to potential welding and accelerated equipment aging due to sudden start-ups and rapid loads.
Innovation Solution
Incorporating a resistive element that allows current to flow through two paths, either through a resistive contact and a fuse element or solely through the fuse element, providing overcurrent protection and limiting inrush currents by reducing the overall current intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse cartridge is used to open electrical circuits under overcurrent conditions, then overcurrent protection is provided, but high inrush currents during circuit closure cause welding of the fuse cartridge to contacts and accelerated equipment aging
Solution Approach 1:
A resistive element is introduced as an intermediary component between the power source and the protected circuit. This resistive element acts as a mediator that temporarily limits inrush currents during circuit closure, preventing welding and reduced equipment lifespan, while allowing full current flow through the fuse element during normal operation and overcurrent protection events
2Object-affected harmful factors
If a resistive element is added to limit inrush currents, then protection during circuit closure is improved, but the device complexity increases
Solution Approach 1:
The resistive element and fuse element are merged into a single cartridge assembly with integrated contact structures. The resistive contact and fuse contact are positioned within the same envelope, allowing both current-limiting and overcurrent protection functions to be combined in one replaceable unit, minimizing additional complexity while maximizing functional integration
3Ease of operation
If the first contact surface has a small area compared to the second contact surface, then correct positioning during installation is ensured, but the electrical contact quality during classic use may be compromised
Solution Approach 1:
The contact surfaces are designed with different local qualities: the first contact surface has a smaller area optimized for temporary installation contact and current limiting, while the second contact surface has a larger area optimized for permanent electrical connection and current carrying capacity during normal operation. Each contact surface is locally optimized for its specific functional requirement
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 effectively protects the circuit from overcurrents and reduces inrush currents during insertion and operation, ensuring reliable and prolonged equipment performance by providing both current limitation and traditional overcurrent protection.
Implementation Method 1
a resistive element (6) intended to ensure the current limiting function in the circuit concerned
Implementation Method 2
This is traditionally achieved by melting a fuse element under the effect of the temperature rise caused by the overcurrent
Implementation Method 3
temperature rise caused by the overcurrent
Data Source
Figure 1~2
Figure 3~4C
Figure 5A~5C
AI summary
The present invention relates to a fuse cartridge (1) comprising a fuse element, a casing (4) housing the fuse element, and two end contacts (2, 3) disposed at each end of the casing (4). The fuse cartridge (1) is characterised in that it comprises at least one resistive element mounted in series with the fuse element.