The 250 A continuous rating (Iu) holds at ambient temperatures up to 50 °C without derating; at 55 °C it still carries 243.3 A, and at 70 °C it's good for 223 A. That thermal curve means you can run it in a hot enclosure and still get nearly full rated current. Breaking capacity is the headline number here: 220 kA at 240 V, 154 kA at 415 V, 36 kA at 440 V, and 17 kA at 690 V. That's a high-interrupting rating — it clears a bolted fault without the arc flash escalating upstream. The 4-pole version handles three-phase plus neutral, and the IP40 front protection keeps dust and small tools out of the breaker face in a clean panel environment.
The 3VA1225-6EF42-0KH0 measures 70 mm deep, 140 mm wide, and 158 mm tall. The width of 140 mm for a 4-pole 250 A MCCB is typical; plan for a 4-module-wide cutout in the mounting plate. The shunt trip (STL) is integrated, and the auxiliary contact block is a 2-aux + 1-trip-alarm switch (HQ).