400 A, 4-pole MCCB with ETU350 — what the ratings mean for your panel
The Siemens 3VA2340-6HN42-0KF0 is a SENTRON molded case circuit breaker rated for 400 A continuous current at 40 °C, with an ETU350 electronic overcurrent release. The 4-pole configuration covers three-phase plus neutral, with the N-conductor protection adjustable OFF, 50%, or 100% of the phase rating. That 242 kA interrupting capacity at 240 V tells you this breaker can clear a bolted fault at the service entrance without upstream fuses — it's sized for high-fault panels where the available short-circuit current is substantial. The interrupting curve drops to 187 kA at 415 V, 85 kA at 440 V, 55 kA at 500 V, and 7.5 kA at 690 V. For a 400 A feeder on a 480 V system, you've got roughly 85 kA of SCCR headroom — enough for most industrial switchboards. The ETU350 release gives you adjustable long-time pickup (Ir), short-time pickup and delay (Isd, tsd), and instantaneous (Ii) settings, plus a ground-fault option if you add the module. The thermal derating curve is flat to 50 °C, then drops to 385 A at 55 °C and 340 A at 70 °C — so if the panel runs hot, you lose about 15% of the ampacity at the top end.
Panel fit and footprint
The 3VA2340-6HN42-0KF0 measures 248 mm tall, 184 mm wide, and 110 mm deep. That 184 mm width (7.2 inches) is a standard 4-pole MCCB footprint — it'll drop into the same DIN-rail or panel-mount cutout as other SENTRON 3VA 4-pole frames. The IP40 front protection means it's rated for indoor panel use where no washdown or dust ingress is expected. Power loss is 96 W maximum at rated current — factor that into your enclosure thermal budget if you're packing multiple breakers in a sealed cabinet.