The Schneider Electric A9CR4240 is an Acti9 REDs residual current circuit breaker (RCCB) — a self-reclosing RCCB rated 40 A with 30 mA earth-leakage sensitivity, Type A, 2P, for 230 V AC 50 Hz phase-to-neutral networks. It is designed for TN-S and TT earthing systems as an outgoer device. The 30 mA sensitivity catches leakage paths that would otherwise go undetected until a fault event — standard for personnel protection in IEC 60364 installations.
Reclosing logic and fault handling
The REDs recloser automates the restart cycle after a transient earth fault: reclosing time is 10 s, maximum operational frequency is 30/hour, with a maximum of 3 consecutive restarts and a minimum 180 s interval between two closings. If an insulation fault persists, the cycle stops and the unit waits — it will only restart when the fault becomes transient. This logic is what separates it from a standard RCCB: it avoids nuisance callouts for self-clearing faults (e.g., moisture on a cable gland) while locking out on a hard fault. Insulation fault diagnosis runs every 2 minutes when a fault is detected. The minimum leakage resistance threshold is 16 kOhm during operation, 8 kOhm when non-operating — below that, the recloser holds the circuit open. The manual test function is active above 100 V, so it can be verified in-circuit without a special test set. Local signalling uses a single green/red LED for RCCB ON/OFF and recloser status.
Width 54 mm (3 x 18 mm pitches), height 106 mm, depth 82 mm. Neutral position is left. Wire stripping length 12 mm, tightening torque 3 N·m. IP20 rated — suitable for enclosed panel mounting only; not for wet or outdoor locations without a secondary enclosure.