The Schneider Electric A9Q31240 is an add-on residual current device from the Acti9 Vigi iC60 range, designed to clip onto the downstream side of an iC60 miniature circuit breaker. It provides earth-leakage protection for a 2-pole outgoing circuit, rated at 40 A with 30 mA sensitivity, Type A-SI (Super Immunised) — meaning it handles pulsed DC fault currents and resists nuisance tripping from high-frequency harmonics or transient surges common on modern electronic loads. The voltage-independent tripping mechanism means the RCD operates even if the neutral or phase voltage is lost, a reliability feature for critical-process circuits where a loss of supply must not disable the ground-fault protection.
Sizing and fit for the DIN-rail panel
Occupies 4 modules of 9 mm pitch (36 mm total width) on standard DIN rail, clip-on mounting. Depth is 73.5 mm, height 91 mm. The bottom tunnel terminals accept 1…35 mm² rigid or 1…25 mm² flexible cable, with a stripping length of 14 mm and tightening torque of 3.5 N·m. Comb-busbar compatible from the bottom, so the outgoing feeder can be daisy-chained to adjacent devices without additional wiring. IP20 rated (IP40 within a modular enclosure), suitable for installation in a clean, dry panel environment.
Electrical environment and selectivity
Insulation voltage 500 V AC, impulse withstand 6 kV. The 8/20 µs impulse withstand of 3000 A per IEC 61009-1 means it survives common lightning-induced or switching surges without damage. The instantaneous time delay (no intentional delay) means it trips as soon as the 30 mA threshold is exceeded — use for circuits where rapid disconnection is required, but coordinate with upstream delayed RCDs to avoid nuisance tripping on a multi-circuit panel.