Siemens 3VA1225-5EF42-0AC0 — 250 A SENTRON MCCB with TM240 Release
The Siemens 3VA1225-5EF42-0AC0 is a 4-pole SENTRON molded case circuit breaker (MCCB) fitted with a TM240 thermal-magnetic release, rated for line-protection duty. 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. The breaker includes two built-in auxiliary switches (HQ design) for status feedback to a PLC or panel indication, without needing an external accessory module.
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. For a 415 V industrial service entrance, the 121 kA rating covers the majority of transformer-fed installations without needing a current-limiting fuse upstream.
Thermal Derating and Panel Integration
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. Mounting dimensions are 158 mm tall, 140 mm wide, and 70 mm deep, fitting standard MCCB panel cutouts.