The Siemens 5SU1156-6KV06 is a combined residual-current device (RCD) and miniature circuit breaker (MCB) — an FI/LS protector — in a single 1+N-pole module. It carries a Type A residual-current sensitivity of 10 mA (IΔn) and a B-curve overcurrent trip at 6 A, with a 6 kA short-circuit breaking capacity. Type A detection means it trips on sinusoidal AC fault currents plus pulsed DC fault currents up to 6 mA smooth DC, covering rectifier-fed loads like switched-mode power supplies and variable-speed drives in modern panels.
The 10 mA residual sensitivity (IΔn) is the key differentiator here — it's an order of magnitude more sensitive than the standard 30 mA Type A used for general socket-outlet protection. A 10 mA device is specified where the installation requires additional protection against lethal shock for circuits supplying equipment in wet locations, medical rooms (per IEC 60364-7-710), or where the earth-loop impedance is too high for a 30 mA device to trip fast enough.
Deployment context
In TT systems, the 10 mA sensitivity helps meet the disconnection times without relying on a low earth electrode resistance.