400 A MCCB with 242 kA interrupting capacity — what that means for your panel
The Siemens SENTRON 3VA2440-6HN32-0HC0 is a 3-pole molded case circuit breaker rated for 400 A continuous current across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. That 400 A holds at every 5 °C step, so it's a straight drop-in for a 400 A bus without recalculating for enclosure heat rise. The interrupting capacity hits 242 kA at 240 VAC, 187 kA at 415/440 V, 121 kA at 500 V, and 9 kA at 690 V. For a 400 A frame, those numbers cover virtually any fault current you'll see on a secondary distribution or large motor branch circuit. This is the line-protection variant (design of the product: line protection), meaning the thermal-magnetic trip curve is set for cable and busbar protection rather than motor or generator protection. It ships with a factory-fitted shunt trip release (STL) and two HQ auxiliary switches — so you can remote-trip it from an E-stop or PLC output and get status feedback without adding an accessory later.
Physical fit and integration — dimensions for panel layout
Dimensions are 248 mm high, 138 mm wide, 110 mm deep. That width (138 mm) is the standard 3-pole MCCB footprint for the 3VA frame at this rating. Power loss is 63.5 W maximum at rated current.
What the breaking capacity numbers actually mean for coordination
The 242 kA at 240 V is the ultimate short-circuit breaking capacity (Icu) — it can interrupt that fault current once and still be functional afterward (though you'd replace it after a fault near that level). At 690 V it drops to 9 kA, which is still adequate for most 690 V drives and transformer secondaries. For selectivity studies: the 400 A continuous rating and the high Icu let this breaker serve as a main or feeder breaker downstream of a transformer, coordinating with smaller branch MCCBs.