The Siemens SENTRON 3VA1225-4EF32-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying 250 A continuously at enclosure ambient temperatures up to 50 °C without derating. Above that, the thermal curve drops to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C — so if this breaker lives in a warm cabinet, the actual continuous current it can handle is lower than the nameplate 250 A.
Breaking capacity and interrupting duty
The interrupting rating depends on the system voltage: 121 kA 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. For a 480 V panel (common in North America), the relevant figure is the 440 V or 500 V rating — interpolate conservatively. The TM240 thermal-magnetic release combines a thermal bimetal for overload protection and a magnetic coil for short-circuit trip; there is no electronic trip unit, no communication function, and no ground-fault monitoring on this variant.
Panel fit and environment
Dimensions: 105 mm wide, 158 mm high, 70 mm deep. The front face carries IP40 protection — suitable for a dry indoor panel, not for washdown or outdoor exposure. Rated insulation voltage is 800 V. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. Maximum power loss at rated current is 57 W — account for that heat in the enclosure thermal calculation.