The Siemens SENTRON 3VA1150-4EF32-0AE0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a 50 A continuous current at 40 °C ambient and a 121 kA interrupting capacity at 240 V — enough to handle high-fault utility feeds or transformer secondaries without cascading upstream gear. Rated insulation voltage is 800 V, and the interrupting curve steps down from 121 kA at 240 V to 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V — check your system voltage against the curve before committing the BOM line.
The breaker holds 50 A from 40 °C through 50 °C, then derates to 49 A at 55 °C, 48 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. If the panel ambient runs above 50 °C, the continuous load must be backed off accordingly — no headroom for a full 50 A at the high end. 130 mm high, 76.2 mm wide, 70 mm deep.