What this MCCB is and why the ratings matter
The Siemens SENTRON 3VA2340-5HN32-0HH0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, designed for line protection in distribution panels. Breaking capacity is 187 kA at 240 V, stepping down to 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V — so at a standard 480 V distribution voltage the available fault current the breaker can safely interrupt sits between the 440 V and 500 V figures, meaning it handles high-capacity transformer feeds without cascading upstream. Continuous current derates above 50 °C: still 400 A at 50 °C, then 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C — the 70 °C figure matches the maximum operating ambient, so in a hot panel the breaker must be loaded to 85 % of its nameplate. Power loss at full rating is 96 W; factor that into enclosure thermal calculations, especially in a sealed stainless cabinet. The breaker ships with a shunt trip (STL) release and a configurable auxiliary switch block carrying 2 auxiliary switches plus 1 trip alarm switch (HQ designation) — the shunt trip lets a remote E-stop or fire-alarm relay drop the main breaker without a handle throw. No ground-fault monitoring module fitted on this variant; if GF protection is needed downstream, it must be added externally. Mounts on a DIN rail or direct-panel plate; dimensions are 248 mm high, 138 mm wide, 110 mm deep — the 138 mm width is a 3-pole frame that fits standard MCCB panel cutouts.