The Siemens 5SY6216-8CC is a 2-pole SENTRON miniature circuit breaker with a D tripping characteristic, rated 16 A at 35 °C and 6 kA breaking capacity per EN 60898. It's designed for high-inrush loads like motor circuits, transformers, or discharge lighting where the D-curve's 10–20× In tolerance avoids nuisance trips on startup.
The D tripping characteristic (10–20× In magnetic release) is the key selection criterion here — it's what differentiates this from a B or C curve. On a 16 A frame, the magnetic trip sits between 160 A and 320 A, so it won't trip on the inrush of a 7.5 kW motor or a 200 VA control transformer. The 6 kA breaking capacity at 230/400 V AC per EN 60898 covers most commercial and light industrial panel fault levels; if your available fault current exceeds that, you'd step up to an S00 or higher-rated industrial MCB. Rated current derates with ambient temperature: 16 A at 35 °C, 15.04 A at 40 °C, 14.54 A at 45 °C, 14.02 A at 50 °C, and 13.47 A at 55 °C. The 2-pole design switches both phase conductors but does not switch the neutral (Neutral Conductor Switching: No). That's standard for a 2-pole MCB on a single-phase or split-phase circuit where the neutral is bonded elsewhere.
Any mounting position is allowed.