The Siemens 5SU9326-1CN16 is a 2-pole RCD-operated circuit breaker (RCBO) from the SENTRON family, combining overcurrent and residual current protection in a single 4-module-width unit. That means it protects both against overload/short-circuit and earth leakage in one device — saving a DIN rail slot versus separate MCB + RCD.
The 16 A rating holds at 30 °C; derate to 14.6 A at 40 °C, 13.9 A at 45 °C, 13.3 A at 50 °C, and 12.5 A at 55 °C. The 30 mA residual-current trip (Type AC) catches sinusoidal AC fault currents to ground. Fine for general-purpose circuits feeding resistive and electronic loads, but not for pulsating DC faults — that would need a Type A device. The 4 kV surge voltage resistance (impulse withstand) covers typical mains transients.
Snaps onto standard DIN rail, 4 module widths (72 mm wide). Depth is 77 mm overall, with 70 mm installation depth — check your enclosure's internal clearances. Feed from top or bottom.