The Schneider Electric A9KR16240 is an Acti9 ID K residual current circuit breaker (RCCB) — a 2-pole, Type AC device rated for 40 A continuous load and 300 mA earth-leakage sensitivity.
The 300 mA sensitivity is the standard for general-purpose earth-leakage protection where personnel protection (30 mA) is not required — common for sub-mains, feeders, or equipment where the leakage budget is higher. That is the correct choice for circuits with resistive and inductive loads that produce smooth leakage waveforms — not for pulsed or DC-leakage scenarios (those need Type A or F). The voltage-independent tripping technology means the device does not need an external power supply to operate; it uses the fault current itself to trigger the mechanism, which is a reliability advantage in installations where the neutral could be lost. Rated breaking and making capacity is Idm 500 A / Im 500 A — this is the short-circuit withstand capability of the RCCB itself, not the breaking capacity of an MCB. Instantaneous tripping — no intentional time delay, so it clears earth faults as fast as the internal mechanism allows. That is the standard for group incomers where selectivity with downstream 30 mA RCCBs is not required, or where the installation relies on cascaded time-delay RCCBs further downstream.
Neutral is on the left, which is the standard orientation for Acti9 RCCBs. The biconnect terminals accept 1…35 mm² rigid or 1…25 mm² flexible cable, top or bottom, with a stripping length of 14 mm and a tightening torque of 3.5 N·m. That is enough cross-section for the 40 A incoming supply and the outgoing distribution. IP20 on the device body, IP40 inside a modular enclosure — fine for dry indoor distribution boards. The operating temperature range is -5…55 °C, storage -25…85 °C, with 95 % relative humidity at 55 °C (tropicalisation class 2 per IEC 60068-1). Suitable for most conditioned or semi-conditioned electrical rooms.