At 240 V it interrupts 330 kA; at 415 V and 440 V that drops to 242 kA, and at 690 V it still handles 52.5 kA, so it can sit on the main or a high-fault subfeed in a 400 V class panel.
Thermal derating and power loss — where the 400 A holds and where it doesn't
At 55 °C it derates to 385 A, at 60 °C to 370 A, at 65 °C to 355 A, and at 70 °C to 340 A. Maximum power loss is 96 W — that's the heat you need to vent in a closed enclosure, especially if the breaker is running near its full rating in a high-ambient cabinet. Latching endurance is 15 000 cycles; operating temperature range is -25 °C to 70 °C, storage -40 °C to 80 °C.
Mounting and integration — fits a standard MCCB footprint
That's a standard 3-pole MCCB envelope for panel mounting — no special adapter plate needed for most switchboard or enclosure cutouts. The shunt trip (STL) and two auxiliary switches (HQ) are factory-installed; verify the wiring diagram for your control voltage before landing the coil wires.