What it is and what it does
The Siemens 5SY4116-7KK11 is a SENTRON miniature circuit breaker (MCB) designed for branch-circuit protection in industrial control panels, railway auxiliary systems, and mechanical-engineering installations. It occupies one modular width (18 mm) on a DIN rail and snaps into any mounting position — no orientation restrictions for the installer. Rated 16 A at 35 °C with a C tripping characteristic, it handles moderate inrush loads typical of motor starters, contactor coils, and small transformers. The breaking capacity is 10 kA per EN 60898 and 20 kA per IEC 60947-2 — the higher IEC figure gives selectivity headroom when coordinating with an upstream 25 kA or 36 kA device. The part is marked for railway applications (design code per the evidence) and carries pollution degree 3, overvoltage category III, and energy limitation class 3 — meaning it limits let-through energy enough to protect downstream wiring in a fault.
Thermal derating and ambient limits
The 16 A rating holds at 35 °C ambient. Above that, derate linearly: 15.02 A at 40 °C, 14.51 A at 45 °C, 13.98 A at 50 °C, 13.44 A at 55 °C, and 12.86 A at 60 °C. If the panel internal temperature runs at 50 °C, size the load at 14 A max to avoid nuisance tripping. Storage and transport range is -40 °C to 75 °C — the MCB can sit in an unheated warehouse or railcar without damage.
Installation and wiring
Mounts on a DIN rail via the quick-assembly system; the 70 mm installation depth leaves clearance for rear-panel wiring. Combined terminals at top and bottom accept copper conductors — no need for separate busbar feed-through. The IP20 rating applies only with conductors connected; keep the panel door closed during washdown. Sealable, halogen-free, and silicon-free construction suits environments where outgassing or contamination must be avoided — medical, food processing, or clean-room adjacent panels.