The 3-pole frame is rated for an insulation voltage Ui of 800 V and delivers breaking capacities from 242 kA at 240 V down to 40 kA at 690 V.
Thermal derating — where the 400 A holds and where it drops
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.
Breaking capacity across voltages — selectivity planning
The interrupting ratings span the common industrial voltage bands: 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 480 V distribution panel (common in North America) the relevant figure is the 440 V rating at 187 kA — that is well above typical available fault current for most secondary substations, so you have headroom for selective coordination downstream. At 690 V, the 40 kA rating still covers most industrial motor-control-center faults.
The MCCB measures 248 mm high, 138 mm wide, and 110 mm deep — a 3-pole frame that fits standard Siemens 3VA switchboard and panelboard mounting patterns. Power loss is 96 W maximum, so account for that heat in the enclosure thermal calculation.
Integrated auxiliary and trip options
Communication function and other measurement functions are present — the ETU850 supports Modbus RTU communication for power monitoring and trip data. There is no undervoltage release or phase-failure detection on this specific configuration.