What it is and what it does
The Siemens 5SL4350-7 is a SENTRON-series 3-pole miniature circuit breaker with a C tripping characteristic, rated 50 A at 400 V AC. It breaks fault currents up to 10 kA under both EN 60898 and IEC 60947-2 — that's the standard for residential and light commercial distribution boards where the prospective short-circuit current at the panel doesn't exceed 10 kA. The C-curve means it trips between 5× and 10× rated current, so it handles moderate inrush from motor starters or capacitor banks without nuisance tripping, while still clearing a hard fault fast enough to protect the downstream wiring. Three modular width units (54 mm wide) snap onto standard DIN rail — any mounting position works. The IP20 rating with connected conductors is typical for enclosed distribution boards; the sealable design lets a utility or facility manager lock the breaker state after commissioning.
What the ratings mean for fit
The 10 kA breaking capacity at 400 V AC is the key coordination figure. At 50 A, the per-pole power loss is 3.6 W in hot operating state. The 72 V DC maximum rating means it can switch DC loads up to that voltage, but the DC breaking capacity isn't separately stated — for DC circuits, derate or use a dedicated DC-rated breaker. Operating temperature range from -40 °C to 75 °C covers most indoor and sheltered outdoor installations.