The Siemens 5SU1646-7FP16 is a SENTRON RCBO — a combined residual-current circuit breaker with overcurrent protection — in a 4-pole configuration. It carries a C-curve trip characteristic rated at 16 A at 30 °C, with a 6 kA breaking capacity certified to both EN 60898 and IEC 60947-2. The unit is designed for 400 V AC, 50 Hz systems and occupies 4 modular width units on a DIN rail.
Thermal derating and real-world current
The 16 A rating is at 30 °C ambient. In a warm panel — say 45 °C — the continuous current drops to 14.8 A; at 60 °C it's 13.4 A. At the maximum rated 70 °C ambient, the RCBO is good for 12.5 A. This derating curve matters when the breaker shares a crowded enclosure with other heat sources.
Installation and environment
Mounts in any position on a DIN rail. The IP20 rating applies when the distribution board is installed with connected conductors — this is standard for enclosed panel gear, not for exposed outdoor use. Pollution degree 3 and overvoltage category III suit it for fixed installations inside industrial switchgear or commercial distribution boards. Supply can enter from either top or bottom.