The Schneider Electric A9N21551 is a Clario iDPN miniature circuit breaker (MCB) rated 40 A with a C-curve trip characteristic, 1P+N poles, and a breaking capacity of 4500 A Icn at 230 V AC 50/60 Hz per EN/IEC 60898-1.
Clip-on mounting to DIN rail, 18 mm width (2 x 9 mm pitches), 81 mm height, 78 mm depth. Neutral on the left. Tunnel terminals accept 0.33–10 mm² flexible or 0.75–16 mm² rigid upstream and downstream; strip length 13 mm, tightening torque 2 N·m. IP20 finger-safe front. The compact 1P+N footprint saves one module width versus a 2-pole breaker when only the phase needs overcurrent protection — common in single-phase sub-distribution boards.
Designed to EN/IEC 60898-1 for household and similar installations. Suitable for isolation (full disconnection on both poles).