The Schneider Electric A9R04440 is an Acti9 iID residual current circuit breaker (RCCB) — 4 poles, rated 40 A, with 300 mA earth-leakage sensitivity, Type A, voltage-independent tripping. The 73.5 mm depth and 72 mm width mean it occupies a standard 4-module slot in an Acti9 enclosure.
The 40 A rated current (In) and 300 mA sensitivity are the two numbers that decide whether this RCCB fits your circuit. 40 A is the continuous load it can carry — sized for a submain or feeder feeding multiple branch circuits, not a single appliance. Type A detection catches pulsating DC residual currents (half-wave rectified) plus sinusoidal AC — common on circuits with electronic loads. Voltage-independent tripping means the RCCB disconnects even if the supply neutral is lost; it stores its own trip energy from the fault current. Rated operational voltage is 380...415 V AC 50/60 Hz, which covers standard three-phase European and UK supplies (400/415 V). Breaking capacity is 1500 A (Idm and Im), adequate for downstream fault clearing in a TN or TT system where the upstream protective device limits fault current. The RCCB is rated for pollution degree 3 (industrial or dusty environments) and operates from -25 °C to 60 °C ambient, with storage from -40 °C to 85 °C. The toggle control, padlocking option, and contact position indicator are standard for panel-building convenience.