What this MCB is and where it fits
The Siemens 5SY4116-7XX01 is a 1-pole SENTRON miniature circuit breaker rated 16 A at 400 V AC with a C tripping characteristic. It snaps onto a DIN rail (18 mm width, 1 width unit) and is meant for branch-circuit protection in industrial control panels, distribution boards, and machinery — the mechanical engineering / industry suitability is stamped right in the spec. The C curve means it tolerates moderate inrush (5 to 10 times rated current) before tripping magnetically — good for motor starters, contactor coils, and small transformer loads where you don't want nuisance trips on energization.
Breaking capacity — what the numbers mean for your panel
This breaker carries three breaking-capacity ratings depending on the standard you're designing to: 10 kA per EN 60898 (the household / commercial standard), 20 kA per IEC 60947-2 (the industrial standard), and 5 kA per UL 1077 / CSA C22.2 No. 235. The 20 kA figure under IEC 60947-2 is the one that matters for most industrial distribution — it tells you the breaker can safely interrupt a fault up to 20 kA without welding its contacts or rupturing the case, which is enough for most secondary distribution panels fed from a transformer of a few hundred kVA. If your panel is UL-listed, the 5 kA UL 1077 rating applies — that's the supplementary-protector limit, not the branch-circuit rating. For a UL 489 listed branch breaker you'd need a different SKU.
Mounting and wiring details
Mounts in any position on a DIN rail (quick assembly system). The 18 mm width (1 width unit) means it takes up one slot in a standard distribution board. Terminals accept solid or stranded copper from 0.75 mm² up to 35 mm² — that's a wide range, so you can land a 6 mm² feeder or a 25 mm² subfeed without adapters. Tightening torque is 2.5 to 3.5 N·m, typical for this class. IP20 with connected conductors — fine inside a closed panel, not for wet locations. Sealable (provision for a lead seal or lockout tag), halogen-free and silicon-free construction. Ambient temperature range -25 to +55 °C, storage -40 to +75 °C.