400 A MCCB with ETU550 — what the ratings mean for your panel
The Siemens SENTRON 3VA2340-8JP32-0AA0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with an ETU550 electronic trip unit that handles line protection duty. That 400 A holds flat through 50 °C — no derating needed until you cross 55 °C, where it steps to 375 A, then 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. So in a warm enclosure or high-ambient switchroom, the effective rating drops; plan your load margin accordingly. Interrupting capacity is the headline number here: 440 kA at 240 V, 330 kA at 415 V and 440 V, 220 kA at 500 V, and 52.5 kA at 690 V. That SCCR covers most industrial service-entrance and distribution applications without cascading upstream — you can coordinate downstream breakers against this fault rating. The 800 V rated insulation voltage (Ui) confirms it's built for 690 V systems with margin. The ETU550 is a communicating electronic trip unit — this breaker carries a communication function, so it can talk to a BMS or SCADA via the SENTRON communication modules. No undervoltage release or shunt trip fitted from the factory, and no ground-fault monitoring version. If you need those, they're accessory-add options on the 3VA platform.
Panel fit and mounting
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That's a standard 3-pole MCCB footprint for the 3VA frame — mounts on a DIN rail or direct panel-mount via the screw terminals. The IP40 front protection means it's fine in a clean indoor enclosure; keep it out of washdown zones unless it's behind a sealed cabinet door. Power loss is 96 W maximum at rated load — factor that into your enclosure thermal calculation if you're packing multiple breakers in a compact panel. The operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C.