What it is and what it does
The Siemens SENTRON 5SQ2370-2YA02 is a 3-pole miniature circuit breaker (MCB) with a C tripping characteristic, rated at 2 A at 400 V AC and a 3 kA breaking capacity per EN 60898. The C-curve means it trips at 5 to 10 times rated current — designed for moderate inrush loads like small motors, transformers, or lighting banks where a B-curve would nuisance-trip on startup. The 3 kA breaking capacity at 400 V AC covers most final subcircuits in residential and light commercial distribution boards; if your fault current exceeds that, you need an upstream current-limiting device. Accepts AC or DC supply voltage, occupies 3 width units, installation depth 55 mm, IP20.
Panel fit and integration
Snap-on DIN rail mount, 3 width units, 55 mm installation depth. No neutral conductor switching. Overvoltage category 3 and energy limiting class 3 — suitable for fixed installations downstream of the main distribution board, where transient overvoltages are already limited by upstream SPDs.