What this MCCB carries and where it fits
The Siemens SENTRON 3VA2340-5HL42-0AA0 is a 4-pole molded case circuit breaker rated for 400 A continuous current, with an ETU320 electronic trip unit and line protection design. Its breaking capacity hits 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V — so it handles high-fault utility feeds and transformer secondaries without cascading upstream. The 800 V rated insulation voltage means it's comfortable on 480 V and 600 V class systems with headroom.
Thermal derating and panel space
This breaker holds its full 400 A rating up to 50 °C ambient. Above that it derates: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, 340 A at 70 °C (–). If your panel runs hot — say a non-climate-controlled enclosure next to a furnace line — factor that curve into the bus and lug sizing. The 184 mm width and 248 mm height are standard for this frame class; the 110 mm depth leaves room for rear-access wiring gutters. IP40 on the front face keeps tools and fingers out but expects a clean, dry enclosure.