The Siemens SENTRON 5SL3203-7MB is a 2-pole miniature circuit breaker rated 3 A at 400 V AC, with a C tripping characteristic and a 4.5 kA breaking capacity per EN 60898. Rated for single-phase operation up to 250 V AC and multi-phase up to 440 V AC. The 72 V DC maximum rating covers control-circuit applications on 48 V or 60 V DC buses, though the primary duty is AC branch-circuit protection.
Width of 36 mm (2 MW) and depth of 76 mm (70 mm behind panel surface). No neutral switching on this 2-pole unit — it switches both phase conductors but does not break the neutral. Touch protection is built in (finger-safe terminals when wired). Halogen-free and silicon-free construction avoids corrosive off-gassing in confined enclosures.
Mechanical service life of 10 000 switching cycles typical — adequate for branch-circuit protection where the breaker is not used as a daily disconnect. For frequent switching duty, consider a dedicated switch or contactor upstream.