The Siemens 5SU9306-1KK16 is a 2-pole SENTRON RCBO — a residual-current-operated circuit breaker that combines overcurrent protection (C-curve, 16 A) and residual current detection (30 mA, type AC) in a single 1 MW (18 mm) wide module. It is designed for final circuits in residential and commercial distribution boards where both overload/short-circuit and earth-fault protection are required in one device. Rated 16 A at 30 °C ambient, 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 — the thermal curve matters if the panel runs hot. The 30 mA residual trip covers personnel protection (indirect contact) and fire prevention.
At 18 mm width (1 MW), it occupies one module position. Depth is 77 mm; installation depth 70 mm. Touch protection is built in (fingertip-safe terminals).