Protection Device with PTC and Thermal Fuses for Arc Suppression
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Solution Overview
Problem
Existing protection devices fail to adequately suppress arcs and fully open circuits during abnormal conditions in high-voltage or high-current applications, and may allow small currents to persist, leading to inefficiencies and potential damage.
Innovation Solution
A protection device comprising a first thermal fuse, a resistive body, and a PTC component, where the second thermal fuse is connected in series with the PTC component, allowing the PTC component to trip and generate heat to fuse the second thermal fuse, effectively diverting current and suppressing arcs, even at high rated voltages and currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single thermal fuse or PTC component is used for protection, then the device structure is simple, but arc suppression and complete circuit opening cannot be achieved under high voltage and current conditions
Solution Approach 1:
The protection device is divided into two independent protection paths: one path contains a thermal fuse for direct overcurrent protection, and the other path contains a PTC component connected in series with a second thermal fuse for arc suppression and complete circuit opening. This segmentation allows each component to perform its specific function optimally without interfering with the other, achieving both reliable protection and complete circuit interruption under high voltage and current conditions.
Solution Approach 2:
Different parts of the protection device are designed with different functional qualities: the first thermal fuse is optimized for rapid response to overcurrent, the PTC component is optimized for arc suppression through its positive temperature coefficient characteristics, and the second thermal fuse is optimized for complete circuit opening. Each component has localized properties tailored to its specific protection role, enabling the overall system to achieve superior protection reliability.
2Reliability
If only a PTC component is used to cut off current, then the structure is simple, but very small leak currents continue to flow and the PTC component must continue working under prolonged abnormal conditions
Solution Approach 1:
The second thermal fuse is extracted as a separate component connected in series with the PTC component. When the PTC component trips and enters high-resistance state, the second thermal fuse receives the full voltage and current, generating heat to fuse and completely open the circuit. This extraction allows the PTC component to perform its arc suppression function temporarily, while the second thermal fuse handles the final complete circuit opening, preventing prolonged operation of the PTC component under abnormal conditions.
Solution Approach 2:
The second thermal fuse acts as an intermediary component between the PTC component and the load. When the PTC component trips, the second thermal fuse serves as the mediator that receives the energy and completes the circuit opening through fusion. This intermediary role allows the PTC component to transition to a non-conductive state without bearing the burden of prolonged abnormal condition operation, as the second thermal fuse takes over to achieve complete circuit interruption.
3Object-affected harmful factors
If a single protection component is used, then the device is simple, but arc occurrence cannot be sufficiently suppressed under high voltage conditions
Solution Approach 1:
The protection device merges two different protection mechanisms into a unified system: the first thermal fuse provides direct overcurrent protection, while the PTC component connected in series with the second thermal fuse provides arc suppression through its positive temperature coefficient characteristics. When abnormal conditions occur, the PTC component heats up and increases its resistance, suppressing arcs, while the second thermal fuse ensures complete circuit opening. This merging of different protection approaches creates a synergistic effect that effectively suppresses arcs under high voltage conditions.
Solution Approach 2:
The protection device uses composite protection architecture combining different material characteristics: the thermal fuse elements provide rapid melting and circuit opening, while the PTC component (typically made of polymer or ceramic materials with positive temperature coefficient) provides arc suppression through resistive heating. This composite approach leverages the complementary properties of different materials to achieve superior arc suppression and protection reliability compared to single-material solutions.
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 ensures complete circuit opening and suppresses arcs, improving voltage resistance and preventing small currents from flowing, thereby enhancing the protection of electric circuits and apparatuses during abnormal conditions.
Implementation Method 1
the resistive body is supplied with a current in an abnormal state so that the resistive body generates heat
Implementation Method 2
the PTC component trips to generate heat, and the heat fuses the second thermal fuse
Implementation Method 3
a bimetal switch and a positive temperature coefficient (PTC) component in parallel for use
Data Source
AI summary
A protection device including: (i) a protection component having a first thermal fuse and a resistive body, the resistive body being supplied with a current in an abnormal state to generate heat, the heat activating the first thermal fuse to cut off the current; (ii) a PTC component; and (iii) a second thermal fuse, the second thermal fuse being electrically connected in series to the PTC component, the first thermal fuse of the protection component being electrically connected in parallel to the PTC component and to the second thermal fuse, and the protection component being activated in the abnormal state so that the PTC component trips to generate heat, the heat blowing the second thermal fuse.