What it is and what it does
The Siemens 5SY4325-7CC11 is a SENTRON miniature circuit breaker (MCB) designed for railway applications. It's a 3-pole unit rated at 25 A with a C trip characteristic, meaning it handles moderate inrush currents common with motor starters and small transformers without nuisance tripping, while still protecting branch circuits from overloads and short circuits. Its breaking capacity is 10 kA per EN 60898, which covers most industrial and commercial panelboard fault levels up to that point. The C-curve trips between 5 and 10 times rated current, so it's a solid fit for general-purpose loads like pumps, conveyors, and lighting banks where the start-up surge isn't extreme.
Where it goes and how it mounts
This MCB snaps onto a DIN rail via the quick assembly system, occupying 3 modular width units (54 mm wide). Mounting position is any orientation, and the installation depth is 70 mm plus the 76 mm overall depth — so it'll fit standard 80 mm deep enclosures with a bit of wire-bending room behind it. IP20 rating with connected conductors means it's protected against finger contact but not water ingress — standard for dry indoor panels. The sealable option lets you lock the toggle position to prevent unauthorized switching.
Environmental and compliance details
Operates from -40 °C up to 75 °C ambient, with derated current values above 35 °C: 23.5 A at 40 °C, 22.72 A at 45 °C, 21.9 A at 50 °C, 21.05 A at 55 °C, and 20.18 A at 60 °C. Humidity tolerance is 95% up to 55 °C, 55% up to 70 °C, and 35% up to 75 °C — so it handles warm, damp environments like pump houses or enclosed switchgear. Halogen-free and silicon-free construction, with pollution degree 3 and overvoltage category III. Designed per IEC 81346-2 and DIN EN 61346-2 for standard industrial and railway control systems. Touch protection is integrated on the terminals.