The Schneider Electric A9KR13240S is a 2-pole residual current circuit breaker (RCCB) from the Acti9 ID K range, rated 40 A with 30 mA earth-leakage sensitivity — Type AC, meaning it detects sinusoidal AC fault currents only.
The 40 A rated current (In) sets the continuous load this RCCB can carry — sized for a main incomer or a sub-feed supplying a mixed load up to that ampacity. The 30 mA sensitivity is the standard threshold for personal protection against indirect contact; it will trip within the instantaneous time band (no intentional delay) when leakage exceeds that level. Type AC means it is suitable for circuits with resistive, capacitive, or inductive loads that produce sinusoidal leakage — not for loads with pulsed or DC fault currents (those need Type A or B). The insulation voltage (Ui) is 440 V AC, which covers the voltage stress in standard low-voltage distribution. Breaking and making capacity is rated at Idm 500 A / Im 500 A — sufficient for fault clearing in a domestic or light commercial panel where the prospective fault current is below that level.
The 36 mm width (4 modules) fits standard enclosures. Terminals accept 1...35 mm² rigid or 1...25 mm² flexible cable, with a stripping length of 14 mm and a tightening torque of 3.5 N.m. IP20 rated (finger-safe) on the front, IP40 inside the modular enclosure — standard for enclosed distribution boards.