What this 4-pole MCCB carries
The Siemens 3VA1225-4EF42-0AF0 is a SENTRON molded case circuit breaker built for line protection in 4-pole configurations. Its TM240 thermal-magnetic release is sized for 250 A continuous at 40 °C, and the breaker holds that rating through 50 °C before it starts to derate — 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. That thermal curve is the one that governs real panel loading; the breaker doesn't trip early if your enclosure runs warm, but you size the conductor and the enclosure ventilation for the temperature you actually see.
Breaking capacity — what it means for fault duty
This MCCB delivers 121 kA interrupting capacity at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, 17 kA at 500 V, and 11.9 kA at 690 V. Those are the numbers that decide whether the breaker clears a fault without upstream fuses or another breaker having to open — high enough for most secondary distribution and motor-control center applications, but the 690 V figure is where you check your available fault current. The rated insulation voltage is 800 V, so the breaker is electrically comfortable at 690 V line-to-line even though the interrupting rating drops there.
Panel fit and auxiliary wiring
The 3VA1225-4EF42-0AF0 measures 140 mm wide, 158 mm tall, and 70 mm deep — a standard 4-pole MCCB footprint that fits SENTRON mounting plates and common DIN-rail adapter brackets. It ships with one auxiliary switch and one trip-alarm switch (HQ type), so you get a remote status contact and a separate trip-indication contact without adding a module. Power loss at full rated current is 57 W; that's the heat you need to account for in the enclosure thermal calculation.
Operating environment
Rated for -25 °C to 70 °C operating ambient and -40 °C to 80 °C storage. The storage range exceeds the operating range, which is typical — the storage limit governs handling and warehousing, not running conditions.