The Schneider Electric A9F43403 is an Acti9 iC60N miniature circuit breaker (MCB) with four protected poles, rated 3 A, B-curve tripping characteristic, and a 50 kA breaking capacity at 415 V AC. It clips onto a standard DIN rail — the 72 mm wide body (9 module pitches at 9 mm each) fits a panel cutout the same way every iC60N does, so if you're swapping an older 4P unit the footprint is a straight drop-in. Rated 3 A continuous, the B curve trips magnetically between 3.2 A and 3.6 A (4 x In ±20 %), which means it clears short-circuit faults fast on predominantly resistive or lighting loads where inrush isn't an issue. For a 4-pole breaker at this current, the thermal-magnetic trip unit handles overloads on all poles simultaneously.
The 50 kA Icu at 380…415 V AC (EN/IEC 60947-2) is the headline number — it tells you this breaker can interrupt a 50 kA prospective fault current without welding its contacts, which is essential for high-fault panels close to the transformer. The same unit also carries a 10 kA Icn at 415 V per EN/IEC 60898-1, the domestic/commercial standard. Dual-rated like this means it's accepted in both industrial (60947-2) and building (60898-1) installations without a separate part number.
Panel integration
The 78.5 mm depth leaves clearance behind a standard 80 mm deep enclosure; the 85 mm height fits under a 90 mm top gland plate. Terminals accept 1…25 mm² rigid or 1…16 mm² flexible — strip 14 mm, torque to 2 N·m. IP20 finger-safe terminals.