Line protection MCCB with a real thermal curve
The Siemens SENTRON 3VA1225-5EF32-0JH0 is a 3-pole molded case circuit breaker rated 250 A at 40 °C, designed for line protection in distribution panels. Its breaking capacity hits 187 kA at 240 V, 121 kA at 415 V, and 75.6 kA at 440 V — enough to handle high-fault utility feeds without cascading upstream. The thermal derating is published all the way to 70 °C: 250 A holds steady through 50 °C, then drops to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. That means you can push the full rating in a ventilated 50 °C enclosure; above that, the curve tells you exactly what you lose per degree.
Auxiliaries and release built in
This variant ships with a shunt trip release (STL) for remote tripping and a 2-auxiliary-switch plus 1-trip-alarm-switch configuration. The auxiliary switches give status feedback to a PLC or annunciator; the trip alarm signals that the breaker opened on a fault, not manually. No undervoltage release, no ground-fault monitoring, no communication module — it's a straightforward line-protection build with the add-ons most panels need.
Panel fit and integration
Dimensions are 105 mm wide, 158 mm high, 70 mm deep. The 105 mm width is a standard 3-pole MCCB footprint for this class — it occupies three 35 mm DIN spaces. Rated insulation voltage is 800 V, so it's comfortable in 480 V and 600 V panels with headroom. Maximum power loss is 57 W; factor that into enclosure thermal calculations, especially if the panel is sealed or has multiple breakers ganged together.