What it is and what it does
The Siemens 5SU1324-2RC40 is a combined residual-current circuit breaker with overcurrent protection — an RCBO — rated 40 A, 2-pole, 4-module width, D characteristic, Type AC, 30 mA trip sensitivity. The D characteristic means the magnetic trip is set to 10–20× In, sized for loads with high inrush like small motors, transformers, or discharge lighting — it avoids nuisance trips on startup while still clearing a hard short. The 30 mA Type AC residual element detects sinusoidal AC fault currents only, which covers the majority of domestic and light commercial circuits; it is the standard choice for general socket-outlet and lighting protection where no DC or pulsed fault components are expected.
Lifecycle and sourcing reality
For BOM-line commitment, the 5SU1324-2RC40 is sourced and quoted to order against an RFQ; availability and current pricing are confirmed at quote time through independent supply channels.
Panel integration notes
The 4-module width (roughly 72 mm on a standard DIN rail) means it occupies four adjacent 18 mm positions in the consumer unit or distribution board — factor this into your fill plan, especially when grouping multiple RCBOs in a compact enclosure. D-curve coordination: upstream MCB or fuse must be sized to handle the let-through energy of a 40 A D-curve device at prospective short-circuit current; typical selectivity tables from the manufacturer should be consulted for the specific fault level at the installation point.