Siemens 3VA1225-5EF42-0AC0 — 250 A SENTRON MCCB with TM240 Release
It carries a continuous current of 250 A at 40 °C, derating to 223 A at 70 °C, and its interrupting capacity reaches 121 kA at 415 V AC — enough to handle high-fault industrial feeds without cascading upstream breakers. The TM240 release combines a thermal bimetal for overload protection and a magnetic coil for short-circuit response, set at 240 A nominal.
Breaking Capacity at Common Distribution Voltages
This MCCB's interrupting 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.
The breaker holds its full 250 A rating from 40 °C through 50 °C, then derates linearly to 223 A at 70 °C. In a panel with multiple breakers ganged together, the 57 W heat dissipation per unit adds up — account for it in the enclosure's thermal budget.