400 A MCCB with ETU350 — what the ratings mean for your panel
The Siemens 3VA2340-5HN32-0DA0 is a SENTRON molded case circuit breaker (MCCB) rated for a continuous current Iu of 400 A, with an ETU350 electronic trip unit providing adjustable overload and short-circuit protection. The 3-pole line-protection variant carries a breaking capacity of 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V — so the interrupting rating you need depends on the system voltage where it's installed. At 690 V the 17 kA figure governs; at 240 V the full 187 kA is available. The ETU350 release lets you set the long-time pickup, short-time pickup, and instantaneous thresholds to coordinate with downstream breakers, which is the main reason to pick this over a fixed-thermal version. Temperature derating is published: the breaker carries the full 400 A up to 50 °C ambient, then steps down to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If your enclosure runs hot — say a sealed panel near a furnace line — that 340 A at 70 °C figure is the one to size against, not the 400 A nameplate. The maximum power loss is 98.5 W, which matters for thermal budgeting inside a compact cabinet.
Integration — mounting footprint and auxiliary options
Dimensions are 248 mm high, 138 mm wide, 110 mm deep. The 138 mm width is the standard 3-pole MCCB footprint for this SENTRON frame size — it occupies the same panel cutout as other 3VA2 breakers, so a panel laid out for a 3VA2 400 A frame accepts this unit without re-drilling. No auxiliary contact is fitted from the factory (auxiliary contact version: without), but the integrated auxiliary trip socket accepts a 3VA9608-0BB25 accessory if you need remote status indication. The undervoltage release (UVR) is built in — design of the auxiliary release is undervoltage release (UVR) — so the breaker trips when control voltage drops, which is common for emergency-stop chains or mains-monitoring circuits.