What it is and what it does
The Siemens 5SY5225-6 is a SENTRON miniature circuit breaker (MCB) with two poles, a B tripping characteristic, and a 10 kA breaking capacity per IEC/EN 60898-2 — also rated 15 kA at DC per IEC 60947-2. That B-curve means it trips between 3 and 5 times rated current, so it's the go-to for residential and light commercial circuits where you're protecting general-purpose wiring and socket outlets, not motor starts or transformer inrush. The 10 kA rating tells you it can safely interrupt a fault current up to that level without welding contacts or cascading upstream — standard for most distribution boards.
DIN-rail fit and panel integration
Snaps onto DIN rail via the quick-assembly system, mounts in any position, and takes up 2 modular width units (36 mm). Depth is 76 mm, installation depth 70 mm — that's the dimension that matters when you're closing the gland plate or door clearance. IP20 with connected conductors means it's protected against solid objects larger than 12 mm but not sealed against moisture; keep it inside the enclosure.
Environmental and compliance
Halogen-free and silicon-free construction, rated for ambient temperatures from -40 °C to 75 °C with derating above 55 °C per the humidity curve. Overvoltage category III, pollution degree 3 — suited for fixed installations in industrial environments where transient overvoltages and conductive dust are expected.