Integrated Fuse Device for Transient Voltage Surge Suppression
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Solution Overview
Problem
Current transient voltage surge suppression systems in industrial applications are costly due to the need for expensive enclosures to contain fragmenting components and prevent fires, and they require complex assembly and additional electronics for fault indication, which increases complexity and cost.
Innovation Solution
An integrated fuse device with a varistor, thermal fuse, and current fuse within an enclosure, where the thermal fuse is connected to the varistor with a copper link and to the device terminal with a steel link, allowing for efficient heat transfer and containment, and the thermal fuse can act as an over-current fuse with a coating to minimize heat sinking and include a deformable body for pressure exertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete components (MOV, fuse, thermal disconnect) are assembled on a printed circuit board or mechanically joined, then the suppression function is provided, but the enclosure cost increases significantly and assembly complexity increases
Solution Approach 1:
The patent combines the MOV, fuse, and thermal disconnect into a single integrated suppression module that is pre-assembled and factory-tested. This merging of discrete components into a unified module eliminates the need for complex on-site assembly of individual components, reducing assembly complexity while maintaining the complete suppression function.
Solution Approach 2:
The integrated suppression module serves multiple functions simultaneously: surge suppression (MOV), overcurrent protection (fuse), and thermal protection (thermal disconnect). This multi-functionality in a single module reduces the number of separate components and assemblies needed, thereby reducing overall device complexity.
2Reliability
If an enclosure is used to contain fragmenting components and prevent fires, then safety is improved, but the enclosure cost becomes a significant portion of the total module cost
Solution Approach 1:
The enclosure is integrated as part of the suppression module housing that contains all components (MOV, fuse, thermal disconnect) in a unified structure. This merged design allows the enclosure to serve dual purposes: protecting components and containing potential failures, thereby reducing the need for separate protective enclosures and lowering overall cost.
Solution Approach 2:
The enclosure is designed to contain and control the effects of component failure (such as MOV rupture or fuse explosion) by directing fragment expulsion in a controlled manner and providing fire containment. This converts the potential harm of component failure into a controlled event that protects surrounding areas, maintaining safety while using a more cost-effective enclosure design.
3Loss of information
If additional electronics are included to indicate thermal disconnect or fusing operation, then fault indication capability is improved, but device complexity and cost increase
Solution Approach 1:
The suppression module incorporates self-indicating features such as visual indicators (e.g., color-coded tags, windows showing component status) or mechanical indicators that automatically show when the thermal disconnect or fuse has operated. These self-service indication mechanisms eliminate the need for additional electronic monitoring circuits, sensors, or control electronics, thereby reducing device complexity while maintaining fault indication capability.
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 integrated device provides comprehensive circuit protection in a single package, effectively suppressing transient voltage surges and sustained overvoltages while reducing the need for additional enclosures and simplifying assembly, meeting industry standards for fault conditions and surge tests.
Implementation Method 1
the thermal fuse is connected to the varistor with a copper link
Implementation Method 2
the thermal fuse comprises a plurality of thermal elements
Implementation Method 3
a power distribution panel having a suppression module included inside. This suppression module typically consists of metal oxide varistors ('MOV'), which provide the surge suppression function
Data Source
AI summary
An integrated fuse device (1) includes a varistor stack (11), a thermal fuse (12), and a current fuse (13) within an enclosure (2) having device terminals (3). The varistor stack (11) is connected to the thermal fuse (12) by a Cu terminal (20) and is connected to the device terminal (3) by steel terminal (10) of smaller cross-sectional area. Being of Cu material and having a greater cross-sectional area, the terminal (20) connected to the thermal fuse (12) has greater thermal conductivity than the steel terminal (10) to the end cap (3). The thermal fuse (12) comprises a plurality of links having a melting point to melt with sustained overvoltage, the links having a diameter in the range of about 2 mm to about 3 mm. The links pass through an elastomer plug (15), which exerts physical pressure on them to assist with opening during sustained overvoltage. Hot melt (18) around solder (17) of the thermal fuse limits heat conduction to back-fill sand.