The Siemens SENTRON 3VA1225-6EF42-0AF0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current Iu of 250 A and a rated insulation voltage Ui of 800 V. Its breaking capacity hits 220 kA at 240 V and 154 kA at 415 V — figures that tell you it can clear a hard fault on a large industrial feeder without the arc or the buswork taking damage. The TM240 thermal-magnetic release handles the overload and short-circuit curve, so you get fixed-trip protection without a separate trip unit to configure. This is the version with one auxiliary switch and one trip alarm switch (HQ) built in, which means you can wire a remote status or shutdown signal straight off the breaker — no add-on module needed.
What the ratings mean for fit
The 250 A rating holds flat from 40 °C to 50 °C, then derates to 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C. If your panel ambient sits at 55 °C, you lose about 7 A of headroom — still enough for a 240 A continuous load, but the derating curve is what you check before committing the BOM line. The 4-pole form factor means it switches all three phases plus neutral, common for a main breaker in a TN-S or TN-C-S system. At 140 mm wide, 158 mm tall, and 70 mm deep, it fits a standard MCCB slot in a SENTRON distribution panel; the IP40 front rating means it's protected against solid objects over 1 mm, but not sealed against dust ingress — fine for a clean indoor switchboard, not for a washdown environment.