The Schneider Electric A9Q61425 is an Acti9 Vigi iC60 add-on residual current device (RCD) — a 4-pole, 25 A unit with 30 mA sensitivity, Type A-SI (Super Immunised) earth-leakage protection. It clips onto the outgoing side of an iC60 MCB via the plug-in electrical connection, making it a modular add-on rather than a standalone breaker.
The unit snap-mounts onto DIN rail and occupies 6 x 9 mm pitches (54 mm width). Bottom tunnel terminals accept 1…25 mm² rigid or 1…16 mm² flexible conductors; tightening torque is 2 N·m with a 14 mm strip length. The IP20 body (IP40 in modular enclosure) suits enclosed distribution boards — not washdown or outdoor locations. The voltage-independent tripping technology means it operates without an external power supply, relying on the residual current itself to trigger the mechanism.
Type A-SI (Super Immunised) provides protection against sinusoidal AC and pulsating DC earth faults, with enhanced immunity to nuisance tripping from high-frequency harmonics or transient surges — relevant on circuits with variable-speed drives, UPS systems, or LED lighting. The instantaneous time delay means no intentional delay before tripping on a fault. Impulse withstand is 8/20 µs, 3000 A per IEC 61009-1.