The Schneider Electric A9N18522 is a 4-pole Acti9 C120 miniature circuit breaker rated 63 A at 30 °C with a D tripping curve (magnetic trip 10–14 x In). The 15 kA Icn at 400 V AC (per EN/IEC 60898-1) covers most commercial and light industrial service-entrance faults; the 10 kA Icu at 440 V AC (per EN/IEC 60947-2) handles the higher prospective fault current you might see on a transformer secondary. Dual-rated to both standards means you can spec it for either residential or industrial duty without juggling two part numbers.
D curve means the magnetic trip holds to 10–14 times rated current — it's built for transformer inrush, motor starting, or any load with a high initial surge that would nuisance-trip a C-curve breaker. At 63 A on a 400 V three-phase system, that's roughly 35 kW of connected load, so it fits a lighting sub-main, a small HVAC panel, or a machine-tool disconnect. The 15 kA Icn at 400 V AC is the rated short-circuit capacity under the domestic-standard test sequence (EN/IEC 60898-1); the 30 kA Icu at 220–240 V AC (per EN/IEC 60947-2) tells you it can interrupt a much higher fault on a 240 V single-phase leg without welding its contacts.
It's a standard catalog item in the Acti9 line, so it's routinely sourced through independent distribution.
The breaker occupies 12 x 9 mm pitches on the DIN rail — 108 mm wide total. Tunnel terminals accept 1–50 mm² rigid or 1.5–35 mm² flexible; strip 15 mm, torque to 3.5 N·m. Neutral is on the left (fixed position). IP20 finger-safe terminals, so no live metal exposed after wiring. The toggle gives clear ON/OFF indication; a separate earth-leakage block can be added downstream if you need RCD protection.