The Siemens 5SN6163-8CP is a 1-pole SENTRON miniature circuit breaker (MCB) rated for 400 V AC at 50 Hz, with a breaking capacity of 6 kA per EN 60898 and 10 kA per IEC 60947-2. It occupies a single 18 mm modular width on the DIN rail, with a depth of 76 mm and an installation depth of 70 mm.
The 6 kA rating under EN 60898 is the standard for residential and light commercial distribution boards — it tells you the breaker can safely interrupt a fault current up to 6 kA at its rated voltage without welding or arcing over. The 10 kA rating under IEC 60947-2 is the industrial counterpart, used when the prospective short-circuit current at the breaker's location exceeds 6 kA.
Single modular width (18 mm) means it replaces any 1-pole MCB in the same footprint without re-drilling the rail or moving adjacent devices. The terminal accepts solid conductors up to 35 mm² — oversized for a 16 A or 20 A circuit, but useful when you're looping through a busbar or feeding a downstream sub-panel. Depth of 76 mm plus the 70 mm installation depth leaves about 6 mm behind the DIN rail for wiring channels; check your enclosure's internal clearance if you're mounting it in a shallow gland plate.