What this MCCB carries and where it fits
The Siemens SENTRON 3VA2225-6HN32-0BH0 is a 3-pole molded case circuit breaker rated for 250 A continuous current at 40 °C, with an ETU350 electronic trip unit configured for line protection. Its interrupting capacity reaches 242 kA at 240 V and 187 kA at 415 V, dropping to 6 kA at 690 V — the high 240 V figure means it handles heavy fault current on the secondary side of a step-down transformer or a low-voltage distribution bus without cascading upstream. The breaker includes an undervoltage release and comes with 2 auxiliary switches plus 1 trip alarm switch (HQ version), so it can signal a remote PLC or SCADA that the breaker has opened on a fault. Rated insulation voltage is 800 V, and the unit is designed for panel-mount integration in a standard SENTRON footprint.
Thermal derating and endurance — what the numbers mean for panel design
The 250 A rating holds flat from 40 °C to 50 °C, then derates linearly to 213 A at 70 °C. In a sealed enclosure with multiple breakers side by side, the 70 °C ambient derate governs the real-world ampacity — plan for 213 A if the panel ambient runs hot. Mechanical endurance is 20,000 cycles, which is typical for a distribution-grade MCCB; not intended for frequent switching duty (that is a contactor's job). Maximum power loss is 50.5 W, so heat dissipation inside the enclosure needs to be accounted for in the thermal budget. Operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C.