What this MCCB does — and what the ratings mean for your panel
The Siemens 3VA2340-5HL42-0AB0 is a SENTRON 4-pole molded case circuit breaker rated 400 A at 40 °C, built for line protection in distribution panels and high-fault industrial feeds. The ETU320 electronic trip unit gives you adjustable overload and short-circuit protection without swapping thermal elements — useful when downstream load profiles shift between seasons or line retools. Breaking capacity is the headline here: 187 kA at 240 V AC, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V. Those numbers mean it can safely interrupt a fault current up to 187 kA at the lower voltage without welding contacts or venting plasma into the enclosure — critical when the transformer is right next to the panel or the service entrance sees utility-grade fault levels. At 690 V the 17 kA figure still covers most industrial motor-drive feeds; just verify your available fault current against the curve before committing the BOM line.
Thermal derating — don't spec the 400 A number alone
The 400 A rating holds from 40 °C through 50 °C ambient. At 55 °C it drops to 385 A, then 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If your panel runs hot — say a sealed enclosure next to a furnace line or a packed MCC — size the breaker for the actual ambient, not the catalog maximum. The 96 W max power loss at full load also factors into enclosure thermal rise; a small stainless box with no fan will cook the trip unit if you ignore it. Dimensions are 248 mm high, 184 mm wide, 110 mm deep — standard 4-pole MCCB footprint for this class. IP40 on the front means it's protected against tools and wires entering the mechanism face, but the terminals themselves are not sealed; mount it in a clean, dry enclosure or add a cover if washdown is nearby.
What you won't find inside
This variant has no undervoltage release, no voltage trip, no communication module, no phase-failure detection, and no ground-fault monitoring. It's a straight line-protection breaker — overload and short-circuit only. If your spec requires shunt trip, UVR, or ground-fault integration, you need a different 3VA2 order code with those options factory-installed.