The Schneider Electric A9Q01225 is an add-on residual current device (RCD) from the Acti9 Vigi iC60 range, designed to plug directly onto the side of an Acti9 iC60 miniature circuit breaker (MCB). It adds earth-leakage protection to the circuit without needing extra wiring — the connection is made through a plug-in interface on the breaker. The unit is rated 25 A, 30 mA sensitivity, Type AC (sinusoidal AC residual currents only), instantaneous trip, for 110...130 V AC 50/60 Hz networks.
Because it is Type AC, it only detects sinusoidal AC leakage — not pulsed DC or smooth DC, so it is suitable for general-purpose socket-outlet circuits and lighting but not for inverter-fed loads, EV chargers, or appliances with rectified supplies. The instantaneous trip (no intentional delay) means it clears faults within the IEC 61009-1 time window, which is fine for final circuits but not for a delayed or selective (S-type) application where coordination with downstream RCDs is needed. The voltage-independent trip mechanism means the RCD operates even if the line voltage is lost — important for safety in a loss-of-supply scenario.