What it is and what it does
The Siemens 5SY4102-8CC is a 1-pole miniature circuit breaker from the SENTRON family, with a D tripping characteristic, rated 2 A at 230/400 V AC (50/60 Hz). It's built for protecting circuits against overload and short-circuit, with a breaking capacity of 10 kA per EN 60898 — enough for most industrial panel feeders. The D-curve means it tolerates high inrush currents, so it's a good fit for motor starters, transformers, or capacitive loads where a B or C curve would nuisance-trip on startup.
Mounting and panel fit
Occupying a single modular width (18 mm) on a DIN rail, with a depth of 76 mm and height of 90 mm. The quick-assembly fastening method and combined top/bottom terminals make it straightforward to wire into a panel. It's rated IP20 with connected conductors — standard for enclosed distribution boards.