The Siemens 5SU9353-7CR25 is a 1P+N RCBO combining overcurrent and residual current protection in a single module. The 30 mA residual sensitivity (Type A) catches sinusoidal AC faults plus pulsating DC faults up to 6 mA smooth DC, covering the majority of modern electronic loads (SMPS, LED drivers, VFDs) that a pure AC-sensitive RCD would miss. The 25 A rated current (In) matches a 4 mm² copper circuit on a 25 A MCB backup; derate if the ambient in the enclosure exceeds 30 °C.
Deployment context
The 1P+N form factor occupies a single module width, so it retrofits into existing board layouts without respacing. Type A residual protection means it is the correct choice for circuits feeding single-phase VFDs, washing machines, or IT equipment — any load that can generate pulsating DC fault currents.