The Siemens 5SU1324-7RC40 is a 2-pole RCBO rated 40 A with C characteristic and Type A 30 mA residual current protection, packaged in a 4-module width. It combines overcurrent and earth-fault protection in a single DIN-rail unit — one part number covers the branch circuit for both overload/short and leakage, saving a module slot over a separate MCB+RCCD pair.
What the ratings mean for the panel
The C characteristic means the magnetic trip operates at 5 to 10 times rated current — 200 to 400 A peak — sized for motor and lighting inrush without nuisance trips on a 40 A circuit. Type A residual detects pulsating DC fault currents up to 30 mA, covering single-phase rectified loads (VFDs, switched-mode supplies) that a plain AC-sensitive RCCD would miss. Four modules (roughly 72 mm on a DIN rail) is the standard footprint for a 2-pole RCBO in this class; plan the enclosure fill accordingly.