The Siemens 5SM3311-6 is a SENTRON residual current circuit breaker (RCCB) — 2-pole, instantaneous design, Type A, rated 16 A at 40 °C on a 230 V AC 50 Hz supply. The 30 mA trip threshold covers the standard personnel-protection requirement per IEC 61008-1, and Type A means it catches pulsating DC fault currents from rectified loads (VFDs, switching power supplies, LED drivers) that a plain AC-only RCCB would miss.
The let-through current is rated 7 500 kA (likely a typo in the source for 7.5 kA²s or similar — treat as the I²t let-through value for coordination with an upstream MCB). Surge-current resistance is 1 kA, so it holds in against capacitor inrush or lightning-induced spikes without nuisance tripping. Thermal derating is published from 40 °C upward: 16 A at 40 °C and 45 °C, then 15.04 A at 50 °C, 14.08 A at 55 °C, 13.12 A at 60 °C, 12.16 A at 65 °C, and 11.2 A at 70 °C. If the distribution board sits in a hot mezzanine or next to a furnace line, size the upstream protective device for the derated current, not the nameplate 16 A.
Depth is 70 mm — check gland-plate clearance if the enclosure is shallow. IP20 with connected conductors, so it belongs inside a distribution board, not in a wet panel.