What this MCCB is and where it lands
The Siemens 3VA2340-5HL42-0BA0 is a SENTRON molded case circuit breaker (MCCB) with a 400 A rated continuous current (Iu) and a 4-pole configuration. It carries an ETU320 electronic trip unit and is designed for line protection in industrial power distribution panels. It's rated for a 800 V insulation voltage (Ui) and delivers breaking capacities from 187 kA at 240 V down to 17 kA at 690 V, which is the range you'd expect for a 400 A frame protecting a main feeder or a large motor branch in a 480 V or 690 V plant. The unit includes an undervoltage release (UVR) as the auxiliary release design, but no auxiliary contact version, no ground fault monitoring, and no communication function — so this is a straight feeder breaker, not a smart or monitored device.
Thermal derating and real-world current
At 40 °C, 45 °C, and 50 °C the breaker holds 400 A without derating. At 55 °C it steps down to 385 A, then 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. That thermal curve is what you'll reference when sizing for a hot panel or a motor control center with other heat sources nearby. Maximum power loss is 98.5 W — a number to include in your panel heat budget, especially if the MCCB sits in a sealed enclosure.
Physical fit and panel integration
Dimensions are 110 mm deep, 184 mm wide, and 248 mm tall. That 184 mm width across four poles means it needs a standard 4-pole MCCB cutout — verify your panel's mounting plate or drawout cradle accepts this footprint before committing the BOM line. It's a fixed (non-drawout) molded case breaker, so it bolts directly to the bus or panel backplane. No auxiliary contacts or shunt trip are integrated from the factory; the UVR is the only internal release.