What the ratings mean for fit
The 5SY4116-8 is a Siemens SENTRON 1-pole miniature circuit breaker with a D tripping characteristic — that's the curve that handles high inrush currents from motor and transformer loads without nuisance tripping. The D curve means the magnetic trip fires at 10 to 20 times rated current, so it's the right call for drives, pumps, or any inductive kick that would pop a B or C curve on startup. Breaking capacity is 10 kA per IEC 60898-1 (the residential/light commercial standard) and 20 kA per IEC 60947-2 (the industrial standard). At DC it's rated 15 kA per IEC 60947-2, and under UL 1077 / CSA C22.2 No.235 it's 5 kA. That 20 kA industrial rating is the one that matters for panel SCCR coordination — it tells you this breaker can interrupt a fault up to that level without welding contacts or cascading upstream. Rated operational voltage is 400 V AC (single-phase up to 440 V, multi-phase also 440 V). DC side is 60 V rated, max 72 V. Frequency is 50/60 Hz. The 18 mm width (1 modular unit) means it snaps into any standard DIN-rail enclosure and leaves room for neighbors — no special adapter needed.
Where it fits in the panel
Mounts in any position on a DIN rail via the quick assembly system. Depth is 76 mm (installation depth 70 mm), height 90 mm, width 18 mm — one modular slot. IP20 with connected conductors, so it's intended for enclosed panels, not wet or dusty environments. Pollution degree 3 and overvoltage category III cover industrial control cabinets with transient exposure. Terminals accept top and bottom combined conductors. Neutral conductor is not switched — this is a 1-pole line breaker only. Sealable for lockout/tagout. Halogen-free and silicon-free construction, so no corrosive off-gassing in sealed enclosures.