PTC Device with Parallel Chip Fuses for High Current Arc Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage PTC elements are unsuitable for high current applications and prone to unpredictable failure during extreme fault conditions, potentially causing electrical arcing and damage due to their low conductivity and risk of becoming highly conductive or combusting.
Innovation Solution
A circuit protection device combining a PTC element with chip fuses having different melting temperatures, where the first chip fuse has a lower resistance than the PTC element in a non-tripped state and the second chip fuse has a higher melting temperature than the first, ensuring a galvanic opening and preventing electrical arcing by diverting current through alternate paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a PTC element is used for overcurrent protection, then electrical arcing is eliminated, but the device cannot handle high current applications due to low conductivity
Solution Approach 1:
The circuit protection function is segmented into two distinct components: a PTC element for arc mitigation and chip fuses for high current handling. The PTC element addresses electrical arcing by increasing resistance during overcurrent conditions, while the parallel chip fuses provide a low-resistance path for high current applications, eliminating the trade-off between arc protection and current capability.
Solution Approach 2:
The circuit protection device achieves multi-functionality by combining the PTC element and chip fuses in parallel. The PTC element provides arc mitigation and resettable protection, while the chip fuses simultaneously provide high current carrying capability and permanent fault clearance, making the overall device suitable for both high current applications and arc prevention.
2Reliability
If a PTC element is subjected to extreme overcurrent conditions, then it may fail in an unpredictable manner, but using it for protection creates risk of catastrophic failure
Solution Approach 1:
The chip fuses act as an intermediary protective layer between the extreme overcurrent conditions and the PTC element. During extreme fault conditions, the chip fuses are designed to open first, preventing the PTC element from being subjected to damaging current levels that could cause unpredictable or catastrophic failure modes.
Solution Approach 2:
The circuit design incorporates chip fuses as a preliminary protective measure against extreme overcurrent conditions. This prior cushioning ensures that if extreme faults occur, the chip fuses will fail in a predictable and controlled manner before the PTC element can be damaged, preventing catastrophic failure.
3Reliability
If chip fuses are used for high current protection, then they can handle high current, but electrical arcing may occur when the fusible element separates
Solution Approach 1:
The invention merges the advantages of both PTC elements and chip fuses by connecting them in parallel. The chip fuses provide the necessary high current capability with low resistance, while the PTC element simultaneously provides arc mitigation. This combination allows the device to handle high currents without the arcing problem that plagues conventional fuse-only designs.
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 device effectively mitigates electrical arcing and ensures safe operation during extreme fault conditions by maintaining a galvanic opening even after the overcurrent condition subsides, preventing damage to connected components.
Implementation Method 1
PTC materials exhibit a relatively low electrical resistance within a normal operating temperature range. However, when the temperature of a PTC material exceeds the normal operating temperature range and reaches a 'trip temperature,' such as may result from excessive current flowing through the PTC material, the resistance of the PTC material increases sharply.
Implementation Method 2
Upon the occurrence of a fault condition, such as an overcurrent condition, the fusible element melts or otherwise separates to interrupt the flow of electrical current through the fuse.
Implementation Method 3
the first terminal electrode is electrically connected to the interface electrode by a via extending through the dielectric substrate
Data Source
AI summary
A circuit protection device including a PTC device having a PTC element, first and second electrodes disposed on opposing first and second surfaces of the PTC element, respectively, first and second chip fuses disposed on the first and second electrodes, respectively, the second chip fuse electrically connected in series with the PTC device, and the first chip fuse electrically in connected parallel with the PTC device and the second chip fuse, the first chip fuse having a lower electrical resistance than the PTC element when the PTC element is in a non-tripped state, wherein a fusible element of the first chip fuse has a first melting temperature and is configured to carry a current higher than the PTC element can carry without tripping, and wherein a fusible element of the second chip fuse has a second melting temperature that is greater than the first melting temperature.