400 A MCCB with 330 kA interrupting capacity — what that means for your main feeder
The Siemens SENTRON 3VA2440-7HL32-0AD0 is a 3-pole molded case circuit breaker rated for 400 A continuous current (Iu) with an interrupting capacity of 330 kA at 240 V AC. That 330 kA figure is the maximum fault current it can safely clear at that voltage — critical for main service entrances or large transformer secondaries where available fault current runs high. At 415 V and 440 V it still clears 242 kA, and at 690 V it handles 52.5 kA, so it stays selective downstream across a range of distribution voltages.
Thermal derating and trip unit
The breaker carries its full 400 A rating from 40 °C up to 50 °C ambient. Above that it derates: 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. The overcurrent release is an ETU320 electronic trip unit — that's a basic thermal-magnetic replacement with fixed settings, not the adjustable ETU600. No undervoltage release, no shunt trip, no ground-fault monitoring fitted on this variant. Power loss is 63.5 W max, which matters for enclosure thermal calculations.
Panel fit and auxiliary contacts
Dimensions are 248 mm high, 138 mm wide, 110 mm deep — standard SENTRON 3VA2 footprint for a 400 A frame. It ships with three factory-fitted auxiliary switches (HQ type). The basic switch assembly is order code 3VA2440-7HL32-0AA0, and the integrated auxiliary trip module is 3VA9608-0BB24, so replacement spares are traceable. No voltage trip, no communication module, no phase-failure detection on this line-protection variant.