The Siemens 3VA2340-5HL42-0AJ0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, with a 4-pole configuration and a maximum breaking capacity of 187 kA at 240 V. It is designed for line protection in industrial distribution panels, where the 400 A frame size covers main feeders or large motor branch circuits. The 187 kA interrupting rating at 240 V gives substantial SCCR headroom for high-fault installations, while the 121 kA at 415 V and 75.6 kA at 500 V keep it viable across common global voltage levels.
Current derating and thermal limits
The 400 A rating holds flat from 40 °C to 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. The operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C. Maximum power loss is 96 W. For a panel builder, this means the breaker can sit in a 50 °C enclosure without derating, but above that the ampacity drops linearly — a consideration when the MCCB shares a compartment with other heat sources.
Physical fit and panel integration
Dimensions are 248 mm high, 184 mm wide, and 110 mm deep. The 110 mm depth is shallow enough for standard 200 mm deep enclosures, leaving room for rear cable lugs or bus bars. The 184 mm width for a 4-pole frame is typical for this class — verify the DIN-rail or mounting-plate footprint against the existing panel layout before ordering.
Selectivity and coordination note
The 4,000 A maximum short-circuit current setting range (600 A minimum) allows the breaker to be tuned for selective coordination with downstream devices. The trip indicator provides local visual status, though there is no undervoltage release, no ground-fault monitoring, and no communication function on this variant. For a site electrical engineer, the lack of a UVR means the breaker will not automatically trip on voltage loss — a deliberate choice for processes that must ride through sags.