What the ratings mean for the panel
The Siemens 5SU9336-7CR20 is a combined residual-current circuit breaker with overcurrent protection (RCBO) in a single 1-module-wide package. It combines a Type A residual-current device (RCD) rated at 30 mA with a C-curve miniature circuit breaker (MCB) rated at 20 A, all in one DIN-rail unit. The 6 kA breaking capacity (Icn) at 230 VAC means it can safely interrupt a fault current up to 6 kA without welding its contacts or cascading the fault upstream — adequate for most final subcircuits in a TN or TT system where the prospective short-circuit current at the board stays under that figure. The Type A RCD detects sinusoidal AC residual currents plus pulsating DC residual currents, which covers modern single-phase electronics (SMPS, LED drivers, variable-speed drives) that a plain Type AC RCD might miss. The C-curve trips at 5 to 10 times rated current (100–200 A magnetic trip), suited for loads with moderate inrush like small motor starters, contactor coils, or banks of LED drivers.
Deployment context
Snap-on DIN-rail mounting for a standard distribution board or sub-distribution enclosure. The 1-module width (roughly 18 mm) saves rail space compared to separate RCD + MCB pairs. Rated for 230 VAC single-phase final circuits — typical use is protecting a lighting circuit, a socket outlet circuit, or a small appliance circuit in residential, commercial, or light industrial panels where both earth-leakage and overcurrent protection are required in one device.