The Siemens 5SJ4301-7HG42 is a SENTRON 5SJ4 miniature circuit breaker rated 1 A at 30 °C with a C tripping characteristic, 3 poles, and a 70 mm depth.
Rated 1 A at 30 °C and 40 °C, derating to 0.97 A at 45 °C, 0.9 A at 50 °C and 55 °C, and 0.88 A at 60 °C. That derating curve is the one that governs real panel ambient — if your enclosure runs at 50 °C, you're limited to 0.9 A continuous. The C characteristic (5–10× In) handles motor inrush and transformer magnetizing currents without nuisance trips, while still clearing short circuits fast enough for cable protection. DC rating is 60 V maximum, so it can switch DC control circuits up to that voltage, but the primary application is AC branch-circuit protection. Vibration resistance tested at 50 m/s² over 25–150 Hz and 60 m/s² at 35 Hz for 4 seconds — enough for machinery-mounted panels on conveyors or compressors. The sealable cover and touch protection add a layer of safety for live-front installations.
IP20 with connected conductors, IP40 in the handle range — fine for enclosed panels; not rated for washdown. Mounting position any, so vertical or horizontal rail orientation works.