What the D curve and 1.6 A rating mean for your panel
The 5SJ4315-8HG42 is a 3-pole miniature circuit breaker from the Siemens SENTRON 5SJ4 series, with a D tripping characteristic and a rated current of 1.6 A at 30 °C. Rated current is 1.6 A at 30 °C, 40 °C, and 45 °C, then derates to 1.5 A at 50 °C and 55 °C, and 1.4 A at 60 °C. The breaker is rated for DC circuits up to 60 V maximum, which covers control-voltage applications like 48 VDC loops.
Physical fit: DIN rail and panel space
Depth is 70 mm, height 121 mm. Mounting position is any — no orientation restriction in the panel.