The Schneider Electric A9D05840 is an Acti9 iC60H RCBO — a residual current breaker with overcurrent protection, combining a 40 A thermal-magnetic MCB and a 30 mA earth-leakage module in one 18 mm-wide unit. It's a 1P + Ns (switched neutral) device, rated for 10 kA breaking capacity at 240 V AC, with a C curve (5 to 10 x In magnetic trip). This is the part you spec when you need both overcurrent and earth-fault protection in a single DIN-rail footprint, saving a module width over separate devices.
The 40 A rating at 50 °C means this RCBO handles a 40 A continuous load in a 50 °C ambient. The integrated RCD module means you don't wire a separate RCCB upstream; it's all in this one 18 mm module, which simplifies panel layout. Breaking capacity of 10 kA at 240 V AC conforming to IEC 61009-2-2 means it can safely interrupt a fault current up to 10,000 A. That's sufficient for most TN earthing system installations at the outgoing circuit level. If your prospective short-circuit current exceeds 10 kA, you'll need an upstream current-limiting device. Strip length is 14 mm top, 13 mm bottom; torque to 3.5 N.m top, 2 N.m bottom. The plug-on neutral connection upstream simplifies busbar integration with the Isobar A or B distribution system.
The A9D05840 is certified to IEC 61009-1, IEC 61009-2-2, and BS EN 61009-1 — the core standards for RCBOs in residential and commercial installations. The IP rating is IP20 (finger-safe terminals when installed) and IP40 for the modular enclosure.