The A9Z25440 is a Schneider Electric Acti9 iID 4-pole residual current circuit breaker (RCCB) rated 40 A with 300 mA earth-leakage sensitivity, Type A, selective time delay.
The 300 mA sensitivity and Type A classification mean this RCCB detects sinusoidal AC residual currents plus pulsating DC residual currents — common with rectified loads like switched-mode power supplies, variable-speed drives, and LED drivers. The selective (time-delayed) characteristic lets it coordinate downstream with instantaneous RCCBs: the downstream unit trips first on a fault, while this one holds to maintain supply to the rest of the circuit. Pollution degree 3 (industrial environment) and IP20 (finger-safe terminals) suit it for enclosed panel mounting.