The Siemens 5SL3250-7MB is a SENTRON miniature circuit breaker — 2-pole, C-curve, 50 A rated current at 400 V AC, with a 4.5 kA breaking capacity per EN 60898. That C-curve means it's built for moderate inrush loads like small motors, lighting banks, and general-purpose branch circuits in residential and light commercial infrastructure. The 4.5 kA rating at 400 V tells you it's sized for standard domestic or light-commercial fault levels, not heavy industrial switchgear. Two modular width units (36 mm) on a DIN rail, so it takes two slots in the panel.
DIN-rail fit and panel integration
Snaps onto a standard 35 mm DIN rail. Depth is 76 mm, height 90 mm, so it clears most shallow enclosures. The 70 mm installation depth means the busbar and wiring pocket fit without forcing the backplate. IP20 with connected conductors — fine inside a closed panel, not for wet locations.
What the ratings mean for the buyer
The 50 A rating at 30 °C is the continuous current it can carry without tripping in a 30 °C ambient. The C-curve trips at 5–10 times rated current for short-circuit protection — so a 50 A C-curve will hold a motor starting surge around 250–500 A for a brief period before clearing a hard fault. The 4.5 kA breaking capacity per EN 60898 is the maximum fault current it can safely interrupt at 400 V AC; if your available fault current at the panel exceeds that, you need an upstream current-limiting device or a higher-rated breaker. Rated for overvoltage category III and pollution degree 2 — standard for fixed-installation distribution boards.