The Schneider Electric A9Y80340 is an Acti9 Vigi iC40 add-on residual current device (RCD) — a voltage-independent, instantaneous-trip unit rated 40 A with 30 mA earth-leakage sensitivity, Type A, 3-pole, for 400 V AC networks at 50/60 Hz. The voltage-independent tripping technology means it detects leakage current and disconnects even if the line voltage is lost — a real advantage on circuits where neutral integrity is uncertain or where nuisance tripping from voltage dips needs to be avoided.
Rated 40 A continuous, so it pairs with a 40 A MCB on the outgoing side — match the breaker frame to the load cable and the RCD to the breaker. Instantaneous trip (no time delay) means it clears fast but can nuisance-trip on circuits with high inrush leakage, like large capacitor banks or long cable runs; for those, a time-delay S-type is the better call, but this is the right choice for general socket-outlet and lighting circuits. Rated insulation voltage 440 V AC, operational voltage 400 V AC — fits standard 230/400 V three-phase networks. Impulse withstand 4 kV per EN/IEC 61009-2-1, pollution degree 3, so it's rated for the typical industrial panel environment with conductive dust or humidity. Dimensions 99.5 x 90 x 74 mm (H x W x D), occupying 4 x 9 mm pitches on the DIN rail. Tunnel terminals accept 1–16 mm² rigid or 1–10 mm² flexible cable, strip length 14 mm, tightening torque 2 N·m. That's enough for a 40 A circuit on 6 or 10 mm² copper — no adapter lug needed.
Compliance: designed to EN/IEC 61009-2-1 (RCD + overcurrent combined standard), which covers the essential safety and performance requirements for the European market. Operating temperature range -25 to +60 °C, storage -40 to +85 °C, altitude up to 2000 m, relative humidity 95% at 55 °C. Electrical endurance 10,000 cycles, mechanical 20,000 cycles — consistent with a switch-disconnect duty class for a panel component.