The Schneider Electric A9R54240 is an Acti9 iID residual current circuit breaker (RCCB) — 2-pole, 40 A rated current, 300 mA earth-leakage sensitivity, Type A. It clips onto a DIN rail, occupies 4 x 9 mm pitches (36 mm wide), and is rated for 220...240 V AC at 50/60 Hz.
The 40 A continuous rating and 1500 A breaking capacity (Idm/Im) tell you this RCCB is sized for a sub-feed or outgoing circuit in a distribution board — it's not a main switch. The instantaneous trip (no time delay) means it clears ground faults immediately — no intentional delay for selectivity with downstream RCCBs, so plan your coordination accordingly. Voltage-independent tripping is a practical advantage: the RCCB doesn't need a neutral-to-earth voltage to operate. It uses the fault current itself to energize the trip solenoid, so it works even if the supply voltage drops or the neutral is lost upstream. That's one less failure mode to chase on a fault. The 6 kV impulse withstand voltage (Uimp) and pollution degree 3 rating mean this unit is designed for installation in a standard industrial or commercial panel where transient overvoltages and conductive dust are expected. It's not a residential-only device.
Installation and wiring
Clip-on DIN rail mount, neutral on the left.