What it is and what it does
The Siemens 5SV9316-7NK20 is a SENTRON RCBO — an RCD-operated circuit breaker that combines overcurrent protection and residual current detection in a single 18 mm wide module. It is a 2-pole (1P+N) instantaneous device rated 20 A with a C tripping characteristic and a Type A fault current sensitivity. The breaking capacity is 6 kA per EN 60898 and IEC 60947-2, which means it can safely interrupt fault currents up to that level in a 230/400 V AC circuit without upstream damage.
Ratings that matter for the panel
The 20 A rating is at 30 °C ambient. Derate to 19 A at 40 °C, 18.4 A at 45 °C, 18 A at 50 °C, and 17.4 A at 55 °C — the full thermal curve is defined, so you can size the branch circuit without guesswork. Maximum power dissipation is 3.8 W, which adds to the enclosure thermal budget. Wire range accepts 0.75 to 16 mm² solid or stranded. That covers most panel wiring from control circuits to feeder taps. The IP20 rating applies once installed in a distribution board with conductors connected — standard for enclosed panel use. Mounting position is any, and supply can enter from top or bottom. Installation depth is 70 mm, overall depth 77 mm. The 18 mm width (1 width unit) snaps onto standard DIN rail. Halogen-free and silicon-free construction matters for environments sensitive to outgassing, like clean rooms or food processing.