The Siemens 5SU9326-7CR25 is a 1P+N RCBO combining overcurrent and residual current protection in a single DIN-rail module.
The 30 mA Type A residual element is the key differentiator here. Type A detects both sinusoidal AC faults and pulsating DC faults — the kind generated by single-phase rectifiers in washing machines, LED drivers, and switched-mode power supplies. If your circuit feeds modern electronics, a Type A RCBO catches faults an AC-only RCD would miss. The C-curve (25 A) means the magnetic trip operates at 5 to 10 times In, so it tolerates motor inrush and capacitive loads without nuisance tripping, but still clears a hard short fast enough to coordinate with a 63 A or 100 A upstream MCB.
Deployment context
The 1P+N topology switches the line conductor only; the neutral is switched internally for isolation but not protected against overcurrent. Rated for 230 V AC phase-to-neutral systems — typical for single-phase final circuits in TN or TT earthing schemes.