The Schneider Electric A9Y85640 is an Acti9 Vigi iC40 add-on residual current device (RCD) — a voltage-independent earth-leakage protection module that clips onto the right side of a compatible Acti9 MCB (1P+N format) to create a combined RCBO assembly.
The 40 A rated current and 230 V AC operational voltage define the load circuit this RCD can protect — sized for a 40 A final subcircuit on a single-phase 230 V supply. The 300 mA sensitivity is a standard for fire protection or circuits where a 30 mA device would nuisance-trip; it is not suitable for personal shock protection (which requires ≤30 mA). Type A-SI adds immunity to high-frequency currents, so it holds in on VFD, UPS, or LED-driver circuits that would trip a standard Type A. Voltage-independent tripping means the RCD operates without needing a separate power supply — it uses the fault energy itself to trip, so it works even if the neutral is lost upstream.
Clip-on mounting to DIN rail, 36 mm width — occupies two 9 mm pitches. Bottom terminals accept 1…16 mm² rigid or 1…10 mm² flexible; tighten to 2 N·m. Wire strip length 14 mm for bottom connection. Electrical connection to the MCB is by screws. IP20 body, IP40 inside a modular enclosure.