What this 400 A MCCB delivers
The Siemens SENTRON 3VA2340-6HN32-0AF0 is a 3-pole molded case circuit breaker rated for 400 A continuous current across the 40 °C to 50 °C ambient range, derating to 340 A at 70 °C. Breaking capacity runs from 242 kA at 240 V down to 7.5 kA at 690 V — that 242 kA figure at 240 VAC covers most North American low-voltage fault scenarios without needing a current-limiting upstream device. The line-protection design (no ground-fault monitoring, no undervoltage release) keeps it straightforward for main feeder or large branch protection where you just need a clean thermal-magnetic trip.
Sizing and thermal derating
At 400 A continuous, this breaker holds its full rating up to 50 °C ambient — above that it steps down: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, 340 A at 70 °C. If your panel ambient runs above 50 °C, size the downstream load against the derated figure, not the nameplate. The 96 W maximum power loss at rated current matters for enclosure heat calculations — that's heat that has to leave the cabinet.
Breaking capacity by voltage level
The interrupting ratings are voltage-dependent: 242 kA at 240 V, 187 kA at both 415 V and 440 V, 121 kA at 500 V, and 7.5 kA at 690 V. That 242 kA at 240 V is the standout — it handles high-fault utility feeds common in North American 277/480 V panels when the breaker sees line-to-neutral faults. At 690 V the 7.5 kA figure is modest; if your system runs at that voltage with higher available fault current, you'll need a current-limiting fuse ahead of it or a different frame.
Physical fit and auxiliaries
Dimensions: 248 mm high, 138 mm wide, 110 mm deep — a standard 3-pole MCCB footprint for this current class. The breaker ships with one auxiliary switch and one trip alarm switch (HQ design) factory-installed, so you get remote status and trip indication without adding a separate accessory module. A visible trip indicator is on the front face. No communication function or voltage-trigger release is built in — this is a straight electromechanical breaker, not a smart unit.