What this MCCB carries and where it fits
The Siemens 3VA1225-5EF32-0BA0 is a SENTRON molded case circuit breaker (MCCB) with a TM240 thermal-magnetic release, rated 250 A continuous at 40 °C and 3-pole construction. It is designed for line protection in distribution panels and motor control centers, with an undervoltage release (UVR) fitted as standard. Breaking capacity varies with system voltage: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V — giving the panel designer clear selectivity headroom across common low-voltage distribution levels. Rated insulation voltage is 800 V, so the breaker is suitable for 690 V line-to-line systems with adequate margin. The TM240 release provides thermal protection for overloads and magnetic protection for short-circuits, tuned for 240 A nominal.
Thermal derating and panel integration
The 250 A rating holds flat from 40 °C through 50 °C, then derates linearly: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. If the panel ambient exceeds 50 °C, size the breaker for the derated current, not the nameplate 250 A. Dimensions are 105 mm wide × 158 mm high × 70 mm deep — a standard 3-pole MCCB footprint that fits most Siemens SENTRON mounting bases and busbar systems without adapter plates. Maximum power loss is 59.5 W at rated load; account for this heat in the enclosure thermal budget, especially when grouping multiple breakers in a sealed panel.