The Schneider Electric A9V31225 is an Acti9 Vigi iC60 add-on residual current device — a 2-pole, 25 A, 30 mA unit with Type A-SI (Super Immunised) earth leakage protection. It clips onto the DIN rail alongside the companion MCB, making it a straightforward fit in a standard distribution board. Rated operational voltage is 230...240 V AC at 50/60 Hz, per EN/IEC 61009-1.
The 25 A rating matches the load current of the protected circuit — sized for a branch feeding a group of outlets or a small lighting panel. The 30 mA sensitivity is the standard touch-protection threshold (IEC 61009-1), meaning it will trip on leakage currents that could be hazardous to a person. Type A-SI (Super Immunised) means it handles pulsed DC fault currents (typical from variable-speed drives or power supplies) without nuisance tripping, and it resists false trips from transient surges. That SI suffix matters if you have electronic loads on the circuit; a standard Type A might drop out when a drive starts up. The residual current tripping is voltage-independent — it will still detect a ground fault and trip even if the phase-to-neutral voltage collapses. That is a reliability feature for circuits where a lost neutral could otherwise leave a fault undetected. Mechanically, it occupies 3 x 9 mm pitches (63 mm wide) on a DIN rail, clips on without tools, and accepts tunnel-type terminals for 1 to 25 mm² rigid cable at the bottom. The IP20 body is fine for enclosed distribution boards; the modular enclosure carries IP40 once installed.