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. 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.
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.