What this 400 A MCCB carries — and where the rating matters
Breaking capacity climbs to 187 kA at 240 V and holds 121 kA at 415 V and 440 V, then drops to 75.6 kA at 500 V and 17 kA at 690 V; that 121 kA at 415 V is the number to check against your transformer fault current. Thermal derating starts at 55 °C: the breaker holds full 400 A up to 50 °C, then steps down to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If your panel ambient runs toward 60 °C, you lose 50 A of headroom — factor that into the feeder sizing. The shunt trip (STL) design of the auxiliary release allows remote tripping from an E-stop or PLC output.
Depth of 110 mm leaves room behind the gland plate for cable bending radius on 400 A lugs. Maximum power loss is 96 W at rated current. That heat has to leave the enclosure — if this sits in a multi-breaker lineup, calculate the cumulative dissipation against your panel cooling. The 15 000-cycle latching endurance tells you it's built for occasional switching, not daily motor starting.