What it is and what it does
The Siemens 5SU1654-1KV32 is a combined residual-current device and miniature circuit breaker (RCBO), branded FI/LS-protector, in a 1+N-pole form factor. It integrates Type AC earth-leakage detection at 300 mA with overcurrent protection on the phase conductor, rated 32 A C-curve and a 10 kA breaking capacity. The 70 mm depth is standard for the Siemens 5SU series, fitting alongside other DIN-rail devices in a residential or light-commercial distribution board.
What the ratings mean for fit
The 300 mA residual sensitivity (Type AC) is sized for circuits where sinusoidal AC earth faults are the primary concern — general socket outlets, lighting, and small appliance circuits in installations where a lower 30 mA threshold is not required by code. The C-curve 32 A overcurrent characteristic handles moderate inrush from motorized loads (pumps, fans, compressors) up to that rating without nuisance tripping. The 10 kA breaking capacity at 230/400 V is sufficient for most residential and light-commercial service-entrance panels where the prospective short-circuit current stays below that level.