What this 400 A MCCB does on the line
It carries a breaking capacity of 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 40 kA at 690 V — so it handles high-fault-current scenarios like transformer secondaries or large motor control centers without cascading upstream. The 400 A rating holds flat from 40 °C through 50 °C; above that it derates to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C.
An undervoltage release (UVR) is integrated, and the ground-fault monitoring uses summation-current formation on the L-conductor. Communication function is present, so it can talk to a higher-level control system for status and trip data.