What this MCCB is and what it does
The Siemens 3VA2340-5HN32-0AC0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection — meaning it sits at the main distribution point or a large feeder in a 400 A circuit, not on a motor branch. Its 3-pole design handles three-phase systems up to 690 V, with interrupting capacity that drops from 187 kA at 240 V to 121 kA at 415 V and 7.5 kA at 690 V. That 187 kA figure at 240 V tells you this breaker is built for high-fault-capacity panels — transformer secondaries or busway feeds where available fault current is high. The 400 A continuous rating holds through 50 °C (–); above that it derates to 385 A at 55 °C and 340 A at 70 °C, which matters if you are packing it into a warm enclosure without forced cooling.
Panel fit and integration
Dimensions are 248 mm high, 138 mm wide, 110 mm deep — a standard SENTRON 3VA frame size that bolts into a panel or mounts on a mounting plate. The 110 mm depth clears most 200 mm-deep enclosures with room for rear-connected busbars. Maximum power loss is 96 W at full rated current; factor that into your thermal budget if the breaker is enclosed with other heat sources. No undervoltage release, no communication module, no ground-fault monitoring — this is a plain line-protection MCCB with two HQ auxiliary switches for remote status indication. If you need those options, you step up to a different variant in the 3VA2 family.