The Siemens 5SY6316-8 is a SENTRON 5SY6 miniature circuit breaker rated 16 A with a D tripping characteristic, 3 poles, and 400 V AC. The 5SY6 design uses a quick-assembly system for DIN-rail mounting, and the 3-pole unit occupies 3 width units (54 mm).
The D-curve trips magnetically between 10× and 20× In, so at 16 A that's 160–320 A instantaneous magnetic trip. That's sized for loads like small motors, solenoid banks, or transformers that draw a brief inrush several times the running current.
Depth is 76 mm, width 54 mm, height 90 mm. Installation depth (including terminals) is 70 mm. Combined terminals top and bottom simplify busbar and ring-tongue wiring.
Humidity tolerance: max 95% RH at 55 °C, derating to 35% RH at 75 °C. The MCB is rated for AC only; DC rating is limited to 72 V max — not a primary DC breaker. Overvoltage category III suits fixed-installation distribution boards. Sealable for lockout/tagout. Approvals include EN 60898, IEC 60947-2, and UL 1077 / CSA C22.2 No. 235 — the UL/CSA rating is 5 kA, so if the panel must carry a UL 508A label, that 5 kA figure is the one the shop will reference.