The Siemens 5SU9353-7CR20 is a 1-pole-plus-neutral residual current circuit breaker with overcurrent protection (RCBO) rated at 20 A with a C-trip characteristic and 30 mA Type A residual sensitivity. The 4.5 kA breaking capacity (Icn) at 230 V AC covers standard commercial and light industrial final circuits where the prospective short-circuit current stays under that threshold — typical for distribution boards fed by a transformer of moderate kVA rating.
Ratings and deployment context
The C-curve (C-Char) means the magnetic trip fires at 5 to 10 times In (100–200 A), suited for loads with moderate inrush like small motor starters, lighting banks, or socket-outlet circuits. Type A RCD detects pulsating DC residual currents plus sinusoidal AC — the minimum for circuits with single-phase rectified loads (washing machines, LED drivers, IT equipment). The 30 mA sensitivity provides additional shock protection in wet or high-integrity locations.