The FKN12A-12D pneumatic load switch-fuse combination unit represents a sophisticated solution for protecting and controlling 12kV distribution networks. Designed for terminal substations and ring network applications, this device integrates a robust load switch with high-performance current-limiting fuses. This combination provides comprehensive protection, with the switch handling normal load and overload currents, while the fuse reliably interrupts high-magnitude short-circuit currents up to 31.5kA, ensuring rapid fault clearance and equipment safety.
The unit's core functionality is enabled by a pneumatic operating mechanism specifically engineered for 12kV duty. This mechanism ensures consistent switching speeds and reliable operation for up to 2000 mechanical operations. The load switch section is capable of making and breaking rated active load currents of 630A, as well as handling closed-loop currents and cable charging currents, demonstrating its versatility in managing various operational states within the distribution grid.
A key design feature is the impactor output energy of 1±0.5J, which ensures precise mechanical coordination between the switch and the fuse during fault conditions. When a fuse operates, it triggers the impactor to automatically trip all three phases, preventing single-phasing and potential damage to downstream equipment like transformers. This intelligent three-phase tripping mechanism is critical for protecting sensitive loads and maintaining system balance.
Therefore, the FKN12A-12D offers a compact, cost-effective, and highly reliable alternative to a circuit breaker for many medium-voltage applications. Its integrated design simplifies protection coordination and reduces panel space. Putai also supports customization and the supply of related medium-voltage accessories to meet system integration needs. For a detailed technical discussion on integrating this unit, contact our engineering team.
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