The Schneider Electric A9FDD225 is an Acti9 iARC arc fault detection device (AFDD) — a 1P+N unit rated 25 A at 230 V AC, 50 Hz, built to EN/IEC 62606 and GB/T 31143. Its job is fire prevention: it detects series and parallel arcing faults that a standard MCB or RCD won't catch, then trips the circuit within 200 ms at 400 V threshold. For a panel-builder or MRO planner, this is the device that goes between the final breaker and the branch circuit in sleeping rooms, dormitories, or high-occupancy spaces where arc-fault protection is code-mandated.
Clip-on mount to DIN rail, 36 mm wide (2 modular spaces), 81 mm tall, 72 mm deep. Neutral on the left, power connection from the top. Tunnel terminals accept 1…16 mm² rigid or 1…10 mm² flexible on the line side; neutral side takes 1…2.5 mm². Tightening torque 2 N·m, strip length 14 mm. Wireman note: the 9 mm phase-to-neutral pitch is fixed, so plan your busbar or ring-tongue layout accordingly — no shifting the neutral position.
Environmental and durability
Rated for -25…60 °C operating, -40…85 °C storage. Tropicalisation severity B per IEC 60068-2-30 (28-day damp heat cyclic). Electrical endurance: 20,000 cycles at 230 V AC, 20 A, resistive load. Mechanical endurance matches at 20,000 cycles. The toggle gives local ON/OFF/fault-trip indication.