The A9R50240 is a Schneider Electric Acti9 iID K residual current circuit breaker (RCCB) — a 2-pole, 40 A, 30 mA sensitivity device for AC networks. It clips onto a DIN rail, occupies 4 module pitches (36 mm wide), and is rated for 220…240 V AC 50/60 Hz operational voltage. The 30 mA trip threshold covers standard personnel protection against direct contact, and the Type AC classification means it detects sinusoidal AC earth-leakage currents only.
Rated at 40 A continuous, this RCCB handles typical lighting, socket-outlet, and small-load circuits in residential or commercial distribution boards. The 30 mA sensitivity is the standard for shock protection in most IEC 60364 installations — it will trip within 300 ms on a 30 mA leak. The voltage-independent tripping technology means the device does not rely on the mains voltage to operate; it uses the fault current itself to energise the solenoid, so it still protects even if the neutral is lost upstream. Breaking capacity is rated at Idm 500 A / Im 500 A, which is adequate for the fault levels typical on the load side of a 40 A MCB in a domestic or light commercial board. The insulation voltage is 440 V AC, giving headroom for 230/400 V systems. Surge current withstand is 250 A (8/20 µs impulse), so it survives the occasional lightning-induced surge without nuisance tripping.
Tunnel-type terminals accept 1…35 mm² rigid or 1…25 mm² flexible cable; strip length is 16 mm. The device is IP20 (finger-safe) with IP40 inside the modular enclosure — fine for a distribution board, not for wet areas.