The Siemens 5SU9304-0KK10 is a 2-pole RCBO — a combined residual-current device and miniature circuit breaker in a single 18 mm-wide module. It belongs to the SENTRON series and is rated for 10 A at 50/60 Hz with a B-curve tripping characteristic, meaning it protects against overcurrents and short circuits while also detecting earth leakage currents down to 30 mA. The 10 kA breaking capacity per EN 60898 and IEC 60947-2 is sufficient for most residential and light commercial distribution boards, and the instantaneous design (no time delay) means it trips without intentional delay on residual faults.
Installation depth is 70 mm, with an overall depth of 77 mm including the housing. Touch protection is built in.
Thermal derating and ambient limits
At 40 °C it derates to 9.4 A, at 45 °C to 9.1 A, at 50 °C to 8.7 A, and at 55 °C to 8.1 A.