What it is and what it does
The Siemens SENTRON 5SU9654-7KK16 is a combined RCD and MCB (RCBO) in a single 2-module-wide (36 mm) package, protecting a single-phase final subcircuit against overload, short-circuit, and earth leakage. The 1P+N design switches the live pole and breaks the neutral, but only the live pole is protected against overcurrent. Rated 16 A at 30 °C with a C-curve tripping characteristic, it handles the inrush from motorized loads like small pumps or compressors without nuisance trips. The 10 kA breaking capacity (per EN 60898 and IEC 60947-2) means it safely clears a fault up to that prospective short-circuit current — enough for most commercial and light industrial distribution boards fed by a transformer of typical size.
Thermal derating — the real current rating in your panel
The 16 A rating is at 30 °C ambient. Inside a warm enclosure — say 40 °C — the continuous current drops to 15.04 A; at 45 °C it's 14.56 A; at 50 °C it's 13.92 A; at 55 °C it's 12.96 A. If your panel runs hot (typical for a crowded DIN-rail cabinet), size the upstream protection and the load accordingly. The RCBO is rated for any mounting position, so vertical or horizontal orientation in the enclosure doesn't change the derating curve.
Panel fit and environment
The RCBO occupies 2 modular width units (36 mm) on a DIN rail, with an installation depth of 70 mm plus the device depth of 77 mm — it clears most standard enclosures. The supply can be fed from either top or bottom, which simplifies busbar routing in a crowded distribution board. Rated IP20 (with the distribution board installed and conductors connected), it's intended for indoor, dry-location use inside a closed panel. Halogen-free and silicon-free construction matters for environments with sensitive electronics or clean-room requirements. The operating temperature range (-40 to 75 °C) covers cold storage and hot machine rooms alike.
Standards and approvals
The breaking capacity is dual-rated: 10 kA per EN 60898 (the household-standard test sequence) and 10 kA per IEC 60947-2 (the industrial-standard test sequence with a different making/breaking duty cycle). Insulation voltage (Ui) is 264 V, overvoltage category III, pollution degree 2 — the typical specification for fixed-installation distribution boards. Surge voltage resistance is 4 kV, and surge current withstand (8/20 µs) is 1 kA. Energy limitation class 3 means the let-through energy is low enough to protect downstream equipment under most fault conditions.