400 A MCCB with 242 kA interrupting — what you're actually getting
The Siemens SENTRON 3VA2340-6JP32-0AB0 is a 3-pole molded case circuit breaker rated for 400 A continuous current, built for line protection duty. That 400 A holds all the way to 50 °C ambient — no derating until you push past 55 °C, where it steps down to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. The interrupting capacity is the headline: 242 kA at 240 V, dropping to 187 kA at 415 V and 440 V, 121 kA at 500 V, and 7.5 kA at 690 V. That means this breaker can clear a 242 kA fault on a 240 V bus without self-destructing — useful for high-fault utility feeds or transformer secondaries where the available short-circuit current is substantial.
Panel fit and thermal management
Footprint is 138 mm wide by 248 mm high by 110 mm deep — a standard MCCB form factor for 400 A class. The 96 W maximum power loss means it throws heat into the enclosure; if you're packing several of these in a single panel, factor that into your ventilation or derating calculation. No undervoltage release, no ground-fault monitoring, no voltage trip — this is a straight line-protection breaker with communication function and two auxiliary switches (HP type).
What the ratings mean for your BOM line
The 400 A continuous rating at 40-50 °C is what governs feeder sizing — a 400 A bus or cable set. The interrupting curve tells you where this breaker fits: it's happiest on 240 V or 415 V systems where the available fault current is high (up to 242 kA and 187 kA respectively). At 690 V the interrupting drops to 7.5 kA, so if you're on a 690 V system with significant fault current, this isn't the right breaker. Storage range is -40 °C to 80 °C; operating range is -25 °C to 70 °C.