The Siemens 5SU1356-1KV25 is a combined residual-current device and miniature circuit breaker (RCD/MCB) — an FI/LS protector — in a single 1+N-pole module. It carries a Type AC residual-current sensitivity of 30 mA and a C-characteristic overcurrent trip at 25 A, with a 6 kA short-circuit breaking capacity. The 70 mm depth fits standard DIN-rail distribution boards.
Type AC detection means the device trips on sinusoidal AC residual currents only — the standard choice for circuits without non-sinusoidal or pulsating DC fault profiles (e.g., basic lighting, resistive heating, socket outlets in residential or light commercial panels). The 30 mA sensitivity provides personal protection against direct-contact faults. The C-curve (25 A) handles moderate inrush from motorized loads like small pumps or compressors up to roughly 5.5 kW at 230 V.