The Siemens 5SU1354-1KV25 is a combined residual-current circuit breaker with overcurrent protection (RCBO) — an FI/LS-protector. It has Type AC earth-leakage detection (30 mA IΔn), 10 kA breaking capacity, and a C-curve 25 A thermal-magnetic trip in a 1+N-pole module, 70 mm width.
What the ratings mean for the panel
Type AC detection means the device responds to sinusoidal AC residual currents — the standard for general-purpose circuits without electronic loads. The 30 mA IΔn is the common threshold for socket-outlet and lighting circuit protection in residential and light commercial panels (IEC 60364-4-41). The 10 kA breaking capacity at the rated voltage is sufficient for most sub-distribution boards with upstream fusing or a main breaker sized to limit prospective fault current below that level. The C-curve (5–10× In magnetic release) avoids nuisance trips on the starting current of small motors, pumps, or capacitor banks — a B-curve would trip earlier, a D-curve would let more inrush through but is typically reserved for transformer or welding loads.