The Siemens SENTRON 5SJ4130-6HG40 is a 1-pole miniature circuit breaker from the 5SJ4 series, carrying a B tripping characteristic and a 30 A rated current at 40 °C.
Rated 30 A at both 30 °C and 40 °C ambient, the 5SJ4130-6HG40 holds full current without derating up to 40 °C. Above that, it steps down: 29.1 A at 45 °C, 28.2 A at 50 °C, 27.2 A at 55 °C, and 26.4 A at 60 °C. For a panel running warm — say, 50 °C inside the enclosure — the breaker still handles 28.2 A continuous, which is a 6% reduction from the nameplate. That derating curve is the one to use when sizing for a crowded cabinet. The DC rating is 60 V maximum, so this single-pole MCB can switch a 60 VDC control circuit or small DC load, but not a 125 VDC battery bank. Vibration resistance is specified at 50 m/s² over 25 to 150 Hz and 60 m/s² at 35 Hz for 4 seconds. That's a machine-tool or conveyor-adjacent environment where moderate vibration is present; the breaker won't nuisance-trip from panel vibration alone.
IP20 with connected conductors, IP40 in the handle area. That's standard for a panel-mounted MCB — not washdown-rated, but fine inside a closed enclosure.