The Siemens 5SU1624-8RC63 is a combined residual current device and miniature circuit breaker (RCBO) rated 63 A, 2-pole, in a 4-module DIN-rail housing. It carries a D tripping characteristic for high-inrush loads and Type A 300 mA residual current protection, covering pulsating DC fault currents that a standard Type AC device would miss.
The 63 A rating and D curve are sized for motor and transformer branch circuits where starting inrush can exceed 10× the full-load current without nuisance tripping. Type A 300 mA residual sensitivity catches pulsating DC faults from single-phase rectifiers, VFD front ends, or switched-mode supplies — common on modern industrial control panels where standard Type AC RCDs would not detect the fault. The 2-pole, 4-module footprint occupies two adjacent DIN positions in a sub-distribution board.