The Siemens SENTRON 5SU9354-7KK20 is a combined RCD and MCB in one 2-module-wide (36 mm) package — an RCBO protecting a single-phase final circuit. It carries a 20 A rated current with C-curve trip characteristic for moderate inrush loads (lighting banks, small motor circuits, control transformers) and integrates a 30 mA type A residual-current element for sinusoidal and pulsating DC fault currents. The 10 kA breaking capacity is rated per both EN 60898 and IEC 60947-2, so it handles domestic and light commercial fault levels without cascading upstream.
What the ratings mean for fit
The C-curve trips between 5× and 10× In, so a 20 A unit holds through the 100–200 A inrush typical of a contactor coil or a bank of LED drivers. The 30 mA type A residual element catches both sinusoidal AC faults and pulsating DC from rectified loads (variable-speed drives, switched-mode supplies) — a common requirement in modern commercial panels. The 10 kA SCCR at 230/240 V is the standard domestic and light-commercial fault level; if your point-of-supply fault current exceeds that, you need an upstream current-limiting device. The 1P+N construction switches the line pole and breaks the neutral, but the neutral pole is not overcurrent-protected — only the line pole has the thermal-magnetic trip. That is normal for single-phase RCBOs; the neutral opens with the line on a fault. The 2 MW width (36 mm) means it occupies two standard 18 mm DIN positions.
Mounting and environment
Snaps onto 35 mm DIN rail in any orientation. The 77 mm depth plus 70 mm installation depth leaves clearance behind a standard 80 mm deep enclosure. IP20 rating applies only when installed in a distribution board with conductors connected — this is a panel-internal device, not surface-mount. Ambient range -40 to 75 °C covers unheated plant rooms and outdoor-rated enclosures. Halogen-free and silicon-free construction matters for high-reliability or clean-environment specs where outgassing contaminates contacts or optics.