The Siemens 5SY8515-8 is a 2-pole (1P+N) miniature circuit breaker from the SENTRON series, with a D tripping characteristic and a 1.6 A rated current.
Rated 1.6 A at 45 °C, derating to 1.56 A at 50 °C and 1.52 A at 55 °C — if your panel ambient runs above 45 °C, the breaker still holds close to its nominal, but the thermal curve shifts. At DC per IEC 60947-2 it's rated 15 kA; under UL 1077 / CSA C22.2 No.235 it's 5 kA — so for North American panels with high available fault current, verify the branch-circuit SCCR against that 5 kA figure.
Mounting position any, so vertical or horizontal busbars work. Depth 76 mm (70 mm installation depth) — check gland-plate clearance if the enclosure is shallow.
Current production — no phase-out or NRND notice on record. The SENTRON 5SY series is Siemens' standard MCB line for IEC markets; this code is the active catalog number. For a BOM freeze, the 5SY8515-8 is a stable line item — no imminent replacement or last-time-buy to track.