The Schneider Electric A9N21374 is a Prodis DT40 miniature circuit breaker rated 6 A with a D tripping curve, 1P+N configuration, and dual-rated breaking capacity of 6000 A Icn per EN/IEC 60898-1 and 10 kA Icu per IEC 60947-2 at 230 V AC. That dual rating matters because it means this MCB qualifies for both residential distribution panels (60898-1) and industrial control panels (60947-2) — one part covers both standards, which simplifies BOM management when a panel needs to meet either code.
D curve and trip behaviour
The D curve magnetic trip operates at 10 to 14 times In (60 to 84 A instantaneous). The thermal-magnetic trip unit handles the overload side; the bimetal element tracks the 6 A continuous rating, so a 7.5 A motor FLA would hold but a 10 A sustained load eventually opens. For a 1P+N breaker, the neutral pole is switched and protected — not just a solid link — which is required on some national wiring rules for final subcircuits.
The 78 mm depth leaves clearance behind most standard enclosure gland plates; the 81 mm height fits within a 4-row DIN rail profile without crowding the wiring duct. That's enough lug for a 6 A feed but also handles the larger conductors sometimes run for voltage-drop reasons on long subcircuits.