The Siemens 5SY4416-8CV is a 4-pole miniature circuit breaker with a D16 tripping characteristic and a 15 kA interrupting capacity at 400 V AC. That 15 kA rating means it can safely clear a fault current up to 15,000 amps on a 400 V line without welding its contacts or rupturing the arc chamber — a spec you need when the available fault current at the panelboard is high, like in industrial distribution downstream of a large transformer.
The D16 curve means the breaker holds its thermal trip until roughly 10 to 20 times rated current — designed for loads with high inrush, like motor starters, transformers, or discharge lighting. The 4-pole configuration (three phases plus neutral) suits three-phase four-wire systems common in European and IEC panels. The 15 kA Icu at 400 V is the ultimate breaking capacity per IEC 60947-2; it certifies the breaker can interrupt one fault at full rating and still be functional afterward (though you'd replace it after a fault anyway).
Panel integration
Snap-on DIN rail mounting for standard 35 mm rail. The 4-pole body occupies four modular 18 mm width units — plan for 72 mm of rail space. Spring-cage terminals accept 0.75 to 35 mm² conductors; strip length 12 mm. The D16 curve and 15 kA rating make it a fit for motor control centers or sub-distribution boards feeding high-inrush loads.