The Siemens 5SY4150-5 is a SENTRON miniature circuit breaker rated 50 A at 35 °C on AC, single-pole, with a tripping characteristic A — the most sensitive curve for protecting semiconductor loads or long cable runs where short-circuit currents are low. It breaks 10 kA per EN 60898 and 15 kA per IEC 60947-2, so it handles fault levels up to that point without upstream coordination issues in a standard distribution board.
The 50 A rating holds at 35 °C; above that the breaker derates linearly to 42.4 A at 60 °C. That matters if the panel runs hot — the actual trip threshold drops, so a continuous load near 50 A may nuisance-trip in a warm enclosure.