The Siemens 5SJ4214-7HG41 is a 2-pole miniature circuit breaker from the SENTRON 5SJ4 series, rated 0.3 A at 30/40 °C with a C tripping characteristic.
Ratings that govern the real load
The 0.3 A rating is not a single number — it derates with ambient temperature. At 30 °C and 40 °C it holds 0.3 A; at 45 °C it drops to 0.29 A; at 50 °C to 0.28 A; at 55 °C to 0.26 A; and at 60 °C to 0.25 A. For a 0.3 A control transformer or a small relay bank, that derating is manageable — but for a load near the limit, factor in the peak ambient.
Vibration resistance is 50 m/s² at 25–150 Hz and 60 m/s² at 35 Hz (4 s), so it holds up on a machine frame or conveyor drive.