What this MCCB delivers on a hot line
The Siemens SENTRON 3VA2340-5HN42-0KL0 is a 4-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, configured for line protection with an ETU350 electronic trip unit. It carries a breaking capacity of 187 kA at 240 V, stepping down to 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V — figures that tell you the fault-clearing headroom at each voltage level, not just a single number. The thermal derating curve is honest: full 400 A holds through 50 °C, then drops to 385 A at 55 °C, 370 A at 60 °C, and 355 A at 65 °C, so if this breaker sits in a warm enclosure or near radiant heat from mill drives, you size the load against the derated value, not the nameplate. Operating ambient range is -25 °C to 70 °C, with storage from -40 °C to 80 °C. The auxiliary contact block carries 2 auxiliary switches + 1 trip alarm + 1 electrical alarm switch (HQ version), and a shunt trip (STL) release is integrated. No undervoltage release, no communication module, no ground-fault monitoring — this is a straightforward line-protection breaker with a remote-trip option.