The A9Q51325 is an Acti9 Vigi iC60 add-on residual current device (RCD) from Schneider Electric, rated 25 A with a 30 mA sensitivity and Type A earth leakage protection. The 30 mA sensitivity catches earth faults that could be lethal through a person (the standard threshold for personal protection), while the Type A designation means it handles pulsating DC residual currents from rectified loads like electronics or variable-speed drives — not just pure AC sine-wave faults.
Mounts via clip-on to DIN rail, occupying 6 x 9 mm pitches (54 mm wide). The tunnel-type terminals on the bottom accept 1...25 mm² rigid cable or 1...16 mm² flexible, with a strip length of 14 mm and a tightening torque of 2 N.m. That's standard for a 25 A outgoing feeder in a domestic or light commercial board. The pollution degree 3 rating (per IEC 60947-2) means it's designed for the conductive dust and condensation you'd find in an industrial panel, not a clean room.
