The Siemens 5SY4650-8 is a 4-pole (3P+N) miniature circuit breaker from the SENTRON series, with a D tripping curve rated at 50 A and 400 V AC. The 10 kA breaking capacity per EN 60898 and 15 kA per IEC 60947-2 give it headroom for industrial panel fault levels; the higher IEC figure is the one to use when coordinating with downstream MCCB or fuses in a 400 V distribution board.
If this breaker sits downstream of a larger MCCB or fuse, the let-through energy (I²t) at 15 kA is low enough that a properly sized upstream device can provide full selectivity up to that fault level. The D curve's higher magnetic threshold also helps with selective coordination against nuisance trips on motor-start transients. Environmental range is wide: -40 °C to +75 °C ambient, with humidity derating above 55 °C (max 95% RH at 55 °C, dropping to 35% at 75 °C). Vibration resistance per IEC 60068-2-6 covers ±1 mm at 5–25 Hz and 50 m/s² at 25–150 Hz — typical for machine-mounted panels.