What this MCCB is and what it does
The Siemens 3VA2225-7HN32-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A continuous current, with a 3-pole configuration and an ETU350 electronic trip unit.
Thermal derating and real-world current
The continuous current rating holds at 250 A from 40 °C through 50 °C ambient. Above that, it derates linearly: 241 A at 55 °C, 232 A at 60 °C, 222 A at 65 °C, and 213 A at 70 °C. If the breaker lives in a hot enclosure — near transformers or in a non-ventilated panel — use the 55 °C or 60 °C column for sizing, not the 40 °C number.
Panel fit and integration
Dimensions are 181 mm high, 105 mm wide, and 86 mm deep — a standard MCCB footprint for a 250 A frame. The IP40 front protection means it is suited for enclosed panel mounting where the front face is behind a door; no washdown or outdoor exposure without an additional enclosure. The 48 W maximum power loss at full load should be factored into the panel thermal budget.
Trip unit and protection features
The ETU350 is an electronic trip unit offering adjustable overload and short-circuit protection curves. It does not include a ground-fault monitoring function, undervoltage release.