What it is and what it does
The Siemens SENTRON 3VA2340-5HL32-0BL0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, designed for line protection in distribution panels. Its interrupting capacity hits 187 kA at 240 V, 121 kA at 415/440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V — so it handles high-fault scenarios downstream of a transformer or generator tie without cascading upstream. That 187 kA at 240 V means it can safely clear a bolted fault on a large 240 V secondary bus, which is the kind of rating you spec when the available fault current is known to be high.
Ratings and what they mean for fit
Continuous current holds at 400 A from 40 °C through 50 °C, then derates to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If your panel ambient runs above 50 °C, the 400 A nameplate doesn't apply — you size against the derated figure. The breaker carries undervoltage release (UVR) and a full auxiliary switch complement: 2 auxiliary switches, 1 trip alarm switch, and 1 electrical alarm switch (HQ design). That means it can signal a remote PLC or SCADA on trip and undervoltage events without an add-on module. Power loss at full load is 98.5 W — account for that heat in your enclosure sizing.
Mounting and integration
Dimensions are 248 mm high, 138 mm wide, 110 mm deep — a standard SENTRON 3VA2 frame footprint. Bolts onto a mounting plate or into a panel bus; no DIN-rail clip on this frame class. The 3-pole block occupies about 138 mm of busbar width. Trip indicator is present, so a quick visual scan confirms a tripped state without opening the door.