The Siemens SENTRON 3VA1112-3EF32-0JA0 is a 3-pole molded case circuit breaker (MCCB) rated 125 A continuous at 40 °C, designed for line protection in commercial and industrial distribution panels. Its TM240 thermal-magnetic overcurrent release handles overloads and short-circuits, while the integrated shunt trip (STL) allows remote tripping for emergency-off or supervisory circuits. Interrupting capacity hits 75.6 kA at 240 V AC, stepping down to 52.5 kA at 415 V and 11.9 kA at 690 V — enough headroom for most secondary distribution applications without cascading upstream.
What the ratings mean for fit
The 125 A rating holds flat from 40 °C to 50 °C, then derates to 114 A at 70 °C — so in a hot panel near the top of its -25 °C to 70 °C operating range you lose about 9 % of capacity. The 800 V rated insulation voltage (Ui) means it's suitable for 480/277 V and 600 V systems with margin, and the 3-pole design covers three-phase loads without a neutral pole. The shunt trip (STL) release is factory-fitted, so you don't need to order a separate accessory for remote trip; it's triggered by applying a control voltage to the release coil. Physical fit: the breaker measures 76.2 mm wide by 130 mm tall by 70 mm deep, which is the standard 3-pole SENTRON 3VA footprint. It mounts on a DIN rail or can be screw-fastened to a backplate. The 28.1 W max power loss matters for thermal budgeting inside a sealed enclosure — at full load you're dumping about as much heat as a small soldering iron.