The Siemens 5SJ4114-8HG40 is a 1-pole SENTRON miniature circuit breaker with a D tripping characteristic, rated 0.3 A at 30 °C and capable of interrupting DC circuits up to 60 V. The D-curve means it tolerates inrush currents 10–20 times rated — sized for motor starters, small transformers, or solenoid loads where a B- or C-curve would nuisance-trip on startup.
Ratings that matter for the panel
Thermal derating is published: 0.3 A holds at 40 °C, drops to 0.29 A at 45 °C, 0.28 A at 50 °C, 0.26 A at 55 °C, and 0.25 A at 60 °C. If the breaker lives in a warm cabinet (say, above 40 °C), the actual continuous current it can carry without tripping is lower than the nameplate — plan the load accordingly.
Physical fit and environmental tolerance
Width is 18 mm (1 modular unit), depth 70 mm, height 90 mm — standard single-module MCB footprint. It mounts on standard DIN rail and can be sealed (tamper-evident cover option).
Vibration and mechanical robustness
Rated for vibration resistance of 50 m/s² at 25 to 150 Hz and 60 m/s² at 35 Hz (4-second dwell). That is roughly 5 g continuous and 6 g at resonance — enough for machine-mounted panels on pumps, compressors, or conveyor drives.