What this MCB delivers
The Siemens 5SY4203-8CV is a 2-pole miniature circuit breaker with a D tripping characteristic, rated 3 A and a breaking capacity Icu of 15 kA at 400 V AC. The D-curve (10–20× In magnetic trip) suits loads with high inrush, such as motor starters, small transformers, or discharge lighting — it avoids nuisance tripping on the startup surge while still protecting against hard faults.
Snap-on DIN rail mounting for standard 35 mm rail. The 2-pole footprint occupies two modular units (36 mm width). Wire termination accepts up to 25 mm² for the line and load side — adequate for a 3 A circuit with voltage drop margin on longer runs.