40 A, 3-pole C-curve MCB for distribution boards
The Schneider Electric A9N21390 is a DT40N miniature circuit breaker from the ProDis range, rated 40 A with a C-curve trip characteristic (magnetic tripping at 5 to 10 × In). Three poles protected, thermal-magnetic trip unit, 50 Hz AC network. The 6 kA Icn at 400 V AC (per EN/IEC 60898-1) covers standard domestic and light commercial distribution boards; the 10 kA Icu at 400–415 V AC (per IEC 60947-2) gives the headroom needed for industrial panel coordination studies.
Breaking capacity and dual-standard rating
This breaker carries two breaking-capacity ratings: 6 kA Icn under EN/IEC 60898-1 (the standard for household and similar installations) and 10 kA Icu under IEC 60947-2 (the industrial standard). The C-curve (5–10 × In) suits mixed loads with moderate inrush, such as lighting banks, small motor groups, and general socket circuits.
Clip-on mount to DIN rail, occupies 6 × 9 mm pitches (54 mm wide). Tunnel terminals accept 0.33–10 mm² flexible or 0.75–16 mm² rigid on both upstream and downstream sides. IP20 finger-safe terminals. ON/OFF toggle indication. Separate earth-leakage block available as an add-on. Pollution degree 3, tropicalisation class 2 per IEC 60068-1 — suitable for humid, non-condensing environments up to 95 % RH at 55 °C.