The Siemens 5SU1156-6KV10 is a combined residual-current and miniature circuit breaker — an FI/LS protector — in a single 1+N-pole module. It pairs a Type A residual-current device (RCD) with 10 mA sensitivity and a B-curve MCB rated at 10 A, all in a 70 mm wide housing. Breaking capacity is 6 kA. This is a current-production part.
The 10 mA trip sensitivity (IΔN) is the key spec here: it's below the standard 30 mA used for general socket-outlet protection. A 10 mA RCD is specified for circuits where even a small leakage current poses a risk — think medical equipment in a patient vicinity, or a wet-area final subcircuit where the body path resistance is low. The Type A designation means it detects pulsating DC residual currents as well as sinusoidal AC, which matters for loads with half-wave rectification like washing machines, LED drivers, or some VFD-fed pumps. The B-curve 10 A MCB trips magnetically between 3 and 5 times rated current (30–50 A), so it's suited for resistive or lightly inductive loads — lighting, small control transformers, or general-purpose socket outlets where inrush is modest.
The 70 mm width (roughly 4 module spaces) is wider than a single MCB because the RCD and MCB functions are integrated in one housing — saves space over two separate devices.