The Siemens 5SY4316-8CV is a 3-pole miniature circuit breaker (MCB) with a D tripping characteristic, rated 16 A at 35 °C and delivering a 15 kA breaking capacity per IEC 60947-2. That D-curve means it's built for high inrush loads — motors, transformers, welding gear — where the starting surge would nuisance-trip a B or C curve. The 15 kA SCCR at 400 V AC tells you it can clear a hard fault without welding contacts or cascading upstream, which is what you need for panel coordination studies.
Derating and ambient conditions
Rated current drops with ambient temperature: 14.83 A at 40 °C, 14.21 A at 45 °C, 13.6 A at 50 °C, 12.86 A at 55 °C. That's a straight derating curve — if your panel hits 50 °C internal, you're effectively running a 13.6 A breaker. Mounting position is any orientation, and the quick-assembly system clips onto standard DIN rail. Three modular width units (54 mm wide) slot into a standard distribution board. Depth is 76 mm, installation depth 70 mm — leaves a bit of finger room behind the gland plate.