The Schneider Electric A9N21564 is a Vigi TG60 add-on residual current device from the ProDis range. It's a 4-pole block rated at 63 A with a 30 mA earth-leakage sensitivity, designed to clip onto a compatible MCB on DIN rail. This part is obsolete per the manufacturer, so it's not something you'll find on the shelf at your regular distributor anymore.
Rated 63 A at 400 V AC phase-to-phase, 50 Hz, this block handles the full load current of a group incomer or sub-main. Type A-SI (Super Immunised) means it's designed to resist nuisance tripping from transient surges or high-frequency leakage that can come from connected electronics, which is handy on mixed loads. It's voltage-independent — the trip mechanism doesn't need a supply voltage to operate, so it still protects if the neutral is lost. Instantaneous time delay means no intentional delay before it trips. Pollution degree 3 and tropicalisation class 2 mean it's suited for industrial environments with some condensation or conductive dust, but the IP20 front limits it to a clean, dry enclosure.
Clip-on mounting to DIN rail, 6 module pitches wide (54 mm). It connects to the upstream MCB via screws, so the MCB must have the compatible screw terminals on its outgoing side. Wire range is 0.75...16 mm² rigid or 0.33...10 mm² flexible, stripped 13 mm, torqued to 2 N·m. The ON/OFF indicator gives local status.
Marked obsolete by Schneider. There is no direct official successor listed in the available records.