What this MCCB delivers in the panel
The Siemens SENTRON 3VA2340-6JP32-0KH0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with a maximum breaking capacity of 242 kA at 240 V AC. That 242 kA figure at 240 V means it can safely interrupt a fault current up to that level without upstream devices needing to clear — critical for high-fault installations like large transformer secondaries or busway feeds. At 415 V and 440 V it still holds 187 kA, and at 500 V it delivers 121 kA, so it covers most industrial distribution voltages with headroom. The 690 V rating drops to 7.5 kA, which is typical for a 400 A frame at that voltage — plan coordination accordingly if your system runs 690 V. This breaker is designed for line protection, not motor circuit protection. It lacks an undervoltage release and ground-fault monitoring as shipped. It carries a shunt trip (STL) and two auxiliary switches plus a trip alarm switch HQ.
Thermal derating — the real-world current curve
The 400 A rating holds flat from 40 °C through 50 °C ambient. At 55 °C it derates to 375 A, at 60 °C to 350 A, at 65 °C to 325 A, and at 70 °C to 300 A. That means if your panel internal ambient runs above 50 °C — common in a crowded enclosure with other heat sources — you need to size the breaker for the derated value, not the nameplate. The maximum operating ambient is 70 °C, and storage range is -40 °C to 80 °C.
Mounting and integration notes
The breaker measures 248 mm high, 138 mm wide, and 110 mm deep. It's a 3-pole fixed-mount MCCB designed for panel or switchgear mounting — not a plug-in base. The 110 mm depth means it fits standard 300 mm deep enclosures with room for wiring gutters. Power loss at full load is 96 W maximum, so factor that into your enclosure thermal calculation if you're stacking multiple breakers in a single section.