The Siemens 5SJ4150-6HG40 is a 1-pole miniature circuit breaker from the SENTRON 5SJ4 series, rated 50 A at 400 V AC with a B tripping characteristic.
IP20 with conductors connected; IP40 in the handle range. That means it is protected against solid objects >12.5 mm (finger-safe) in normal operation, but not against dust ingress or water. Suitable for clean, dry indoor panels — not for washdown or outdoor enclosures without a higher-rated outer cabinet.
Halogen-free and silicon-free construction, which matters for clean-room or sensitive electronics environments where outgassing can cause contact corrosion or optical haze. Vibration resistance tested at 50 m/s² over 25–150 Hz and 60 m/s² at 35 Hz for 4 seconds — typical for industrial machinery mounted on a panel wall. Overvoltage category 3 per IEC 60664, meaning it is designed for fixed installations where transient overvoltages are controlled by the upstream distribution — standard for a sub-distribution board or final branch circuit.