400 A line protection with ETU350 — what the ratings mean for your panel
The Siemens SENTRON 3VA2340-6HN32-0BA0 is a 3-pole molded case circuit breaker rated for 400 A continuous current (Iu) at 40 °C, with no derating needed up to 50 °C — it holds the full 400 A through that range. Above 50 °C the thermal curve steps down: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. That means in a warm panel enclosure you size for the ambient, not the nameplate. The interrupting ratings are the real story here: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 40 kA at 690 V. These are high-fault numbers — this breaker handles utility-grade available fault current without cascading upstream. The rated insulation voltage is 800 V, so it's comfortable on 480 V and 600 V class systems with headroom. It ships as a line-protection version (no ground-fault monitoring, no communication function, no phase-failure detection). The overcurrent release is the ETU350 electronic trip unit, and it includes an undervoltage release (UVR) as the auxiliary release — designated as 3VA9608-0BB11. No auxiliary contact version is fitted, and there is no trip indicator on the front face.
Physical fit and panel integration
Dimensions are 248 mm high, 138 mm wide, and 110 mm deep. That 138 mm width is the standard 3-pole MCCB footprint for this SENTRON frame — it occupies three 45 mm module positions on a DIN rail or panel-mount base. The 110 mm depth means it clears most 200 mm deep enclosures with room for rear busbars. Maximum power loss is 98.5 W at rated load — account for that heat in your enclosure ventilation calculation, especially if you're grouping multiple breakers in a row.