MCCB for line protection — 250 A, 4-pole, high interrupting capacity
The Siemens 3VA1225-6EF42-0JA0 is a SENTRON molded case circuit breaker designed for line protection in distribution panels. It carries a 250 A continuous rating at 40 °C ambient across all four poles, with a TM240 thermal-magnetic overcurrent release and an integrated shunt trip (STL) for remote tripping. Interrupting capacity is 220 kA at 240 V AC, 154 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V — figures that cover most low-voltage fault scenarios without cascading upstream. Rated insulation voltage is 800 V.
Thermal derating and operating envelope
Continuous current holds at 250 A from 40 °C through 50 °C ambient. Above that, it derates linearly: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. Maximum power loss is 57 W. Operating temperature range is -25 °C to 70 °C; storage range extends from -40 °C to 80 °C. These limits govern the breaker's placement in unconditioned enclosures or outdoor-rated panels.
Dimensions and panel fit
The breaker measures 140 mm wide, 158 mm high, and 70 mm deep. It mounts on a DIN rail or directly to a backplate via the standard SENTRON footprint. The 4-pole width occupies roughly 5.5 inches of rail space — plan the enclosure layout accordingly.