The Siemens 5SY6416-8 is a 4-pole SENTRON miniature circuit breaker with a D tripping characteristic, rated 16 A at 400 V AC. The D-curve means it tolerates inrush currents up to 10–20× rated current before tripping magnetically — sized for motor, transformer, or welding loads that draw a heavy start surge without nuisance tripping on the branch. Breaking capacity is 6 kA per EN 60898 for general distribution, and 15 kA per IEC 60947-2 for industrial feeder duty; the higher figure gives you coordination headroom in a panel with high prospective fault current. Mounts on DIN rail via the quick-assembly system, occupies 4 width units (72 mm), and accepts conductors from 0.75 to 35 mm² solid or stranded — enough cross-section for the 16 A feed plus downstream tap-offs.
Depth of 76 mm and height of 90 mm fit standard DIN-rail enclosures; the 70 mm installation depth leaves clearance for rear-connected busbars. Ambient range -25 to +55 °C, storage down to -40 °C, with humidity derating above 55 °C.