The Siemens SENTRON 3VA2340-5HN32-0JA0 is a 3-pole molded case circuit breaker rated for 400 A continuous current from 40 °C through 50 °C, meaning it holds its full nameplate rating without derating across typical panel ambient temps — you don't lose headroom just because the enclosure runs warm. Above 50 °C it derates stepwise: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C (–). That thermal curve matters when you're packing breakers into a tight switchboard; the 400 A frame gives you a real-world cushion before you need to step up a frame size. Breaking capacity is the headline number for fault coordination: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V (–). The ETU350 electronic trip unit gives adjustable long-time, short-time, and instantaneous pickup settings — it's not a fixed thermal-magnetic, so you can coordinate selectively with downstream breakers on a panel schedule. Line protection version means it's configured for feeder protection, not motor or generator duty.
Mounting and integration — fits standard 3-pole MCCB footprint
Dimensions are 248 mm high, 138 mm wide, 110 mm deep — that's 9.76 by 5.43 by 4.33 inches. For a panel with several breakers at this frame size, factor that into your thermal calculation; it's not trivial.