The Schneider Electric A9D51640 is an Acti9 iDPN Vigi residual current circuit breaker with overcurrent protection (RCBO) in a 1P+N format, combining a 40 A thermal-magnetic MCB and a 30 mA earth-leakage module in a single 36 mm wide unit that clips onto a DIN rail. Rated 40 A with a B-curve magnetic trip threshold of 3 to 5 times In, it breaks 4500 A Icn at 220...240 V AC 50 Hz per EN/IEC 61009-2-1 — enough for residential and light commercial outgoing circuits where fault levels stay under that ceiling. The integrated 30 mA residual-current element covers personnel protection (indirect contact) and fire prevention on the same pole, saving a DIN module versus separate MCB + RCCD.
The 40 A rated current and B-curve suit general-purpose socket-outlet circuits and lighting final subcircuits where inrush is modest — think office, retail, or residential distribution boards. The 4.5 kA Icn at 230 V is the standard domestic breaking capacity in many European markets; if your service entrance fault current exceeds that, you need an upstream current-limiting device or a higher-rated breaker. The 30 mA sensitivity is the standard threshold for socket-outlet protection in most IEC-based wiring codes; it catches leakage through damaged insulation or a person touching a live part. The RCBO trips on both overcurrent and earth leakage, so a single device clears both faults — no need for a separate RCCD downstream.
Terminals accept 1 to 16 mm² rigid or 1 to 10 mm² flexible (with or without ferrule); tighten to 2 N·m. Strip length 15 mm. IP20 on the body, IP40 inside a modular enclosure — standard for a distribution board. Local signalling shows ON, OFF, and fault-trip status on the toggle. The 73 mm depth fits standard shallow enclosures; verify clearance for the toggle throw and cable bending radius.