The A9N21464 is a Prodis Vigi DT40 add-on residual current device (RCD) from Schneider Electric, designed to clip onto a compatible MCB on DIN rail. It is a 3-pole unit rated 25 A with 30 mA earth-leakage sensitivity, Type A-SI (Super Immunised) — meaning it handles pulsed DC fault currents and resists nuisance tripping from high-frequency harmonics or transient surges common on modern electronic loads. Voltage-independent tripping keeps it functional even if the line voltage drops.
This part is marked obsolete by the manufacturer.
Clip-on mounting to a DIN-rail MCB; the 9 mm pitch occupies 4 modules (36 mm). Rated operational voltage 400 V AC phase-to-phase at 50 Hz, insulation voltage 400 V AC, impulse withstand 6 kV. Pollution degree 3 per EN 61009-1 — suitable for industrial enclosures where conductive contamination is controlled. IP20 finger-safe terminals; wire range 0.75…16 mm² rigid or 0.33…10 mm² flexible downstream, tighten to 2 N·m, strip 13 mm.
Instantaneous tripping (no intentional delay). Ambient operating range -25…60 °C, storage -40…60 °C, 95 % RH at 55 °C, altitude up to 2000 m. Electrical endurance 10,000 cycles. Complies with EN 61009-1 and EN 61009-2-1.