400 A MCCB with ETU550 — what the ratings mean for your panel
The Siemens SENTRON 3VA2340-6JP32-0DC0 is a 3-pole molded case circuit breaker rated for 400 A continuous current (Iu), using the ETU550 electronic trip unit. That 400 A holds from 40 °C through 50 °C ambient; at 55 °C it derates to 375 A, and at 70 °C it's 300 A — so if your panel runs hot, the real ampacity is lower than the nameplate. The interrupting ratings are substantial: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 40 kA at 690 V. For a main feeder or large motor branch, that means it clears high-fault events without upstream coordination headaches. This breaker includes an undervoltage release (UVR) and comes with 2 auxiliary switches (HQ version) factory-fitted. It also has a communication function — the ETU550 supports data exchange over the SENTRON communication bus, so you can pull trip data and status into a PLC or BMS without adding a separate module. The max power loss is 98.5 W, which matters for enclosure thermal management if you're stacking multiple breakers.
Panel fit and integration
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That's a standard 3-pole MCCB footprint for the 400 A frame — it mounts on a DIN rail or directly to a backplate via the screw terminals. The 110 mm depth is shallow enough for most 600 mm deep enclosures with room for wiring gutters. The ETU550 trip unit is field-replaceable, and the auxiliary switches (2 HQ) are plug-in, so you can swap them without pulling the breaker.