The Siemens 5SU9406-1KK16 is a 1P+N RCD-operated circuit breaker from the SENTRON 5SU9 series, combining overcurrent protection and residual current detection in a single 18 mm wide unit. The residual current element is type AC, sensing sinusoidal AC fault currents only.
At 40 °C the continuous current drops to 15.04 A, at 45 °C to 14.56 A, at 50 °C to 13.92 A, and at 55 °C to 12.96 A. If the distribution board runs warm — say 45 °C inside the enclosure — the load must be limited accordingly. The unit dissipates 0.75 W maximum under rated conditions.
The 5SU9406-1KK16 occupies one width unit (18 mm) on a DIN rail. Touch protection is provided on the terminals.