The Schneider Electric A9N21544 is a Clario iDPN miniature circuit breaker rated 3 A with a C-curve (magnetic trip 5–10 x In), 1P+N poles, and a breaking capacity of 4500 A Icn at 230 V AC 50/60 Hz per EN/IEC 60898-1. The 1P+N format switches the live conductor and provides a switched neutral, common in single-phase final subcircuits where you want isolation on both poles. Clip it onto a DIN rail, torque the tunnel terminals to 2 N·m, and it occupies 2 x 9 mm pitches (18 mm wide).
Integration details for the panel builder
Clip-on mounting to DIN rail, 18 mm wide (2 x 9 mm pitches), 78 mm deep, 81 mm tall. Tunnel terminals accept 0.33–10 mm² flexible or 0.75–16 mm² rigid on both upstream and downstream sides; strip 13 mm of insulation. The toggle switch gives local ON/OFF indication. Pollution degree 3 per IEC 60947-1, meaning it tolerates conductive pollution in a typical panel environment. Separate earth-leakage protection block can be added if needed.