The Siemens 5SV9316-1PK20 is a SENTRON 5SV9 series RCD-operated circuit breaker — an RCBO that combines overcurrent protection and residual current detection in a single 18 mm wide, 2-pole (1P+N) package. It's rated 20 A at 50 Hz with a C tripping characteristic, meaning it handles moderate inrush from motor or lighting loads without nuisance tripping, and breaks faults up to 6 kA per EN 60898 and IEC 60947-2. The 20 A rating is at 30 °C ambient; derate to 19 A at 40 °C, 18 A at 50 °C, and 17.4 A at 55 °C — the thermal curve matters if this lands in a crowded enclosure or near a heat source.
Width is 18 mm (1 width unit), depth 77 mm with 70 mm installation depth. Mounts in any position on DIN rail. Touch protection is built in; IP20 rating assumes the distribution board is installed with conductors connected. Supply feeds from below per the design.