What this MCCB carries and where it fits
The Siemens SENTRON 3VA2340-5HL32-0HH0 is a 3-pole molded case circuit breaker rated 400 A continuous (Iu) with an ETU320 electronic overcurrent release. It is configured for line protection — meaning it sits at the incoming feeder or main distribution point, not downstream on a motor or branch circuit. The interrupting ratings tell the story: 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. That kind of short-circuit capacity is sized for high-fault industrial switchgear, not a light commercial panel. The 248 mm height, 138 mm width, and 110 mm depth put it in the larger frame of the 3VA platform — expect it to need real estate on the DIN rail or mounting plate. The ETU320 is a basic electronic trip unit — it gives you adjustable overload and short-circuit protection but no communication, no ground-fault monitoring, and no phase-failure detection. If your BOM calls for a breaker that reports back to a PLC or has integrated ground-fault, this isn't that part. What it does have is a shunt trip (STL) release built in, plus two auxiliary switches and one trip-alarm switch (HQ) as standard. The maximum power loss is 96 W — enough heat that you need to think about ventilation in a sealed enclosure, especially if you're derating the current above 55 °C. The continuous current holds at 400 A up to 50 °C, then steps down: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. That derating curve is the one that governs real-world fit in a warm panel.
What the ratings mean for the panel
The 800 V rated insulation voltage (Ui) tells you the breaker is built for 690 V line-to-line systems with margin — common in European 400/690 V industrial networks. The 15000 latching endurance cycles is typical for a main breaker that sees infrequent switching; it is not a switching duty device. The storage range of -40 °C to 80 °C means it can sit in an unheated warehouse or shipping container. Operating range is -25 °C to 70 °C, which covers most plant-floor conditions but not a foundry or oven line. The 138 mm width is standard for a 400 A frame in the 3VA family; if you're swapping from another manufacturer's 400 A frame, check the mounting hole pattern and bus-bar spacing — the footprint is not universal.