What this RCBO is and what it does
The Siemens SENTRON 5SU9406-0KK16 is an RCD-operated circuit breaker combining overcurrent and residual current protection in a single 18 mm wide module. It is a 1P+N design.
Ratings and what they mean for your panel
The 16 A rating at 30 °C is the base current; it derates to 15.04 A at 40 °C, 14.56 A at 45 °C, 13.92 A at 50 °C, and 12.96 A at 55 °C. If your distribution board runs warm — common in a crowded enclosure — use the derated figure for the actual ambient to avoid nuisance tripping. The B curve means the magnetic trip operates at 3 to 5 times In (48 to 80 A), so it's a good fit for resistive and general-purpose loads with modest inrush, not for motor starting or transformer primaries. Breaking capacity is 6 kA per both EN 60898 and IEC 60947-2, which covers the majority of domestic and light commercial installations where the prospective short-circuit current at the point of installation is under 6 kA. The insulation voltage is rated 264 V, overvoltage category III, pollution degree 2 — standard for fixed-installation switchgear in a distribution board. The module occupies 1 modular width unit (18 mm) and mounts on DIN rail in any position. Supply can enter from either top or bottom, which simplifies wiring in a pre-populated board. Installation depth is 70 mm, overall depth 77 mm. IP20 rating applies when installed in a distribution board with conductors connected.