Advanced Arc-Triggered Fuse Solution for High-Voltage and High-Current Applications
I. Research Background and Core Issues
1.1 Research Background
With the continuous expansion of power system scale and the increasing short-circuit capacity, higher requirements are imposed on fault current limiting protection equipment. Existing mainstream solutions include superconducting fault current limiters (SFCL), hybrid current-limiting circuit breakers, and hybrid current-limiting fuses. Among these, hybrid current-limiting fuses have become the market preferred choice due to their high technological maturity, cost-effectiveness, and wide application.
However, existing technologies have two major limitations:
• Electronically Controlled Type: Relies on sensitive electronic components and an external control power supply, making it prone to malfunction or failure due to component failure or loss of control power. Its reliability is constrained by external conditions.
• Arc-Triggered Type: While offering advantages such as simple structure, strong anti-interference capability, compact size, and low cost, its rated current (typically ≤600A) and breaking capacity (typically ≤25kA) are relatively low, making it difficult to meet the urgent demands of high-voltage and high-current industrial applications (e.g., large-scale metallurgy, chemical plants, data centers).
1.2 Core Contradiction
The performance enhancement of arc-triggered fuses faces a fundamental contradiction: the trade-off between rapid operation and current-carrying capacity. To achieve fast operation (low pre-arcing I²t value), a small cross-sectional area of the fuse element constriction is required. Conversely, increasing the rated current-carrying capacity necessitates a larger constriction cross-sectional area. Enlarging the cross-sectional area increases the pre-arcing I²t value, causing delayed operation during short circuits. This delay allows the actual short-circuit current to rise, ultimately leading to breaking failure.
II. Solution: Key Technological Breakthroughs and Innovative Design
2.1 Working Principle
This solution employs an arc trigger as the core sensing and triggering unit. Its structure primarily consists of two copper plates, an internal silver fuse element (with specifically designed constrictions), filler material, and an enclosure. The breaking process is as follows:
- Arcing: When a short-circuit current occurs, the fuse element constriction rapidly melts and arcs, generating an initial arc voltage.
- Triggering: This arc voltage rapidly ignites the parallel-connected explosive interrupter (electric detonator).
- Current Commutation: The interrupter explodes, forming a high-resistance path, forcing the short-circuit current to commutate to the parallel arc-extinguishing fuse branch.
- Breaking: The arc-extinguishing fuse arcs, generating an extremely high arc voltage that forces the current to zero, achieving rapid current-limiting interruption.
2.2 Core Innovation: High Constriction Current Density Design
The trigger current value (I₁) is a key parameter determining breaking success, needing to remain within the optimal range of 8-15kA. For arc-triggered designs, the rated current is strongly correlated with the trigger current.
The core breakthrough of this solution lies in significantly increasing the constriction current density. Through theoretical derivation:
• Trigger current value I₁ ∝ (pre-arcing I²t * di/dt)^(1/3)
• Pre-arcing I²t value ∝ (constriction cross-sectional area (S))²
Conclusion: Under the same rated current and short-circuit conditions, a higher constriction current density requires a smaller constriction cross-sectional area (S), thereby reducing the pre-arcing I²t value. This ensures rapid operation even under extremely high short-circuit currents, enabling reliable breaking. The design goal of this solution is to elevate this metric from the current product level of ~1000 A/mm² to over 3000 A/mm².
2.3 Structural Optimization and Simulation Verification
• Simulation Tool: ANSYS 11.0 software was used for parametric modeling based on APDL language, enabling precise calculation of fuse element resistance and simulation of the pre-arcing process.
• Fuse Element Structure Selection: The traditional circular hole design was abandoned in favor of a rectangular hole structure. This structure maximizes the current-carrying share in non-constriction regions, achieving lower resistance and higher current-carrying capacity within the same volume, perfectly resolving the contradiction between current-carrying capacity and speed.
• Parameter Optimization: Key parameters such as constriction width (b), hole width (c), spacing (d), and thickness (h) were optimized through multi-dimensional simulations. The optimal solution for minimized resistance was sought while ensuring manufacturing feasibility (e.g., avoiding element breakage or deformation).
Optimization Result: The final design achieved a fuse element resistance of 15.2 μΩ and a constriction cross-sectional area of 0.6 mm², perfectly meeting the requirements for a 40 kA breaking capacity.
III. Performance Verification and Test Results
3.1 Temperature Rise Test
• Test Conditions: Applied 2000 A AC current for stable continuous operation.
• Test Results:
o The measured cold resistance was 15.0 μΩ, highly consistent with the simulation value (15.2 μΩ), validating the model's accuracy.
o Temperature rises at key parts met standards (85 K at the constriction, approximately 47 K at the terminals).
o The current-carrying capacity confirmed a rated current of 2000 A. The calculated constriction current density reached 3300 A/mm², far exceeding similar domestic and international products.
3.2 Short-Circuit Trigger Test
• Test Conditions: A simulated circuit was set up to generate a prospective symmetrical short-circuit current of 40 kA.
• Test Results:
o The measured trigger current value was 15.1 kA, highly consistent with the simulated predicted value (15 kA) and within the optimal range of 8-15 kA.
o The generated arc voltage reached 50 V, sufficient to reliably ignite the electric detonator within microseconds, demonstrating its rapid and reliable operation.
IV. Conclusion and Advantages
This solution successfully developed a high-performance arc-triggered fuse. The core conclusions and advantages are as follows:
- Fundamental Breakthrough: Through innovative rectangular hole fuse element design and parameter optimization, the inherent contradiction between current-carrying capacity and operating speed in arc triggers was resolved. The constriction current density was elevated to an industry-leading level of 3300 A/mm².
- High Performance Indicators: The product is suitable for 10 kV voltage levels, achieving a rated current of 2000 A and a breaking capacity of 40 kA, meeting the needs of high-voltage and high-current industrial applications.
- High Reliability: The purely mechanical arc-triggering mechanism is passive and requires no control, eliminating dependence on electronic components and external power supplies. It offers strong anti-interference capability and reliable operation.
- Verifiable Technology: The ANSYS-based simulation model showed high consistency with measured results, providing an efficient and reliable tool and methodology for product design and optimization.
