The Schneider Electric A9DF7640 is an Acti9 iCV40N residual-current circuit breaker with overcurrent protection (RCBO), combining a 40 A thermal-magnetic MCB and a 300 mA earth-leakage module in a single 36 mm wide, 1P+N package.
The unit's breaking capacity is 6000 A Icn at 230 V AC, tested to EN/IEC 61009-2-1. For coordination, the limitation class is 3 per the same standard, meaning it lets through less energy than a class-3 threshold, which helps the upstream breaker stay selective on a hard fault.
Earth-leakage and trip technology
The integrated earth-leakage protection is set at 300 mA sensitivity — that's a common level for general distribution circuits where you want to guard against insulation faults but avoid nuisance tripping from normal leakage on long cable runs or equipment with filters. The trip unit is thermal-magnetic: the thermal bimetal handles overloads (slow, inverse-time), and the solenoid handles short-circuits (instantaneous above the magnetic threshold). Both the overcurrent and residual-current functions are in one housing, so it saves a DIN-rail position compared to a separate MCB and RCCB.
Installation and wiring details
Torque them to 2 N·m, and strip 14 mm of insulation. The toggle gives local ON/OFF and fault indication, which is handy for a maintenance electrician tracing a tripped circuit without pulling the front cover.