What this 400 A MCCB delivers
The Siemens SENTRON 3VA2340-5JP32-0KH0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, holding that rating through 50 °C before derating to 375 A at 55 °C and 300 A at 70 °C. Its interrupting capacity hits 187 kA at 240 V and 121 kA at 415 V, dropping to 7.5 kA at 690 V — numbers that govern whether this breaker clears a fault before the upstream device takes the hit. Designed for line protection, it includes a shunt trip (STL) release and two auxiliary switches plus a trip alarm switch, with a communication function for integration into a monitored distribution system.
Thermal derating and coordination reality
The 400 A continuous rating holds flat from 40 °C to 50 °C — no derating needed in a typical 40 °C panel. Above that, the curve drops 25 A per 5 °C step: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, 300 A at 70 °C. That matters when you're stacking breakers in a hot enclosure or near a transformer. The interrupting capacities across voltages — 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 500 V, 7.5 kA at 690 V — define the fault-clearing envelope for selectivity studies. If your upstream transformer can deliver 100 kA at 415 V, this breaker's 121 kA gives you headroom.
Panel fit and wiring notes
Dimensions are 110 mm deep, 138 mm wide, 248 mm high — a 3-pole frame that fits standard switchgear cubicle cutouts. The auxiliary switch complement (2 aux + 1 trip alarm) is built into the supplied basic switch variant 3VA2340-5JP32-0AA0. Shunt trip release (STL) is included for remote tripping. Communication function is onboard, so this breaker can talk to a BMS or PLC without an add-on module. Power loss at full load is 96 W — factor that into enclosure ventilation if you're packing multiple breakers in a sealed cabinet.