Siemens SENTRON 3VA2440-6HN32-0DC0 — 400 A MCCB with ETU350
The Siemens SENTRON 3VA2440-6HN32-0DC0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current Iu of 400 A at 40 °C and a rated insulation voltage Ui of 800 V. Breaking capacity hits 242 kA at 240 V and 187 kA at 415 V, so it handles high-fault utility feeds or transformer secondaries without cascading upstream — a solid pick for main breaker duty in a distribution panel. The ETU350 electronic trip unit manages the protection curve; the breaker ships with an undervoltage release (UVR) and two HQ auxiliary switches for status feedback to a PLC or annunciator.
Thermal derating and panel fit
Full 400 A rating holds through 50 °C ambient; above that it steps down to 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C — plan your enclosure ventilation if the breaker sits near other heat sources. Dimensions are 248 mm high, 138 mm wide, 110 mm deep — standard 3-pole MCCB footprint for a 400 A frame, mounts on a backplate or DIN rail via the optional adapter. Maximum power loss is 66 W at rated current; factor that into your thermal budget for sealed enclosures.