The Schneider Electric A9R90240 is a 2-pole residual current circuit breaker (RCCB) from the Acti9 iID K range, rated at 40 A with 30 mA Type A earth-leakage sensitivity. The 30 mA trip threshold catches ground faults through live conductors, not just the line-to-neutral path, because the trip mechanism is voltage-independent: it works even if the neutral is lost. That matters out here in the grease where a corroded neutral connection on a pump panel could otherwise let a fault ride through. Breaking and making capacity is 500 A (Idm and Im), and it withstands an 8/20 µs impulse surge of 200 A per EN/IEC 61008-1. The earth-leakage protection is instantaneous — no intentional time delay — so it clears fast on a direct ground fault.
Clip-on mounting on a DIN rail, 36 mm wide (four 9 mm pitches). Terminals accept up to 35 mm² rigid or 25 mm² flexible, with a stripping length of 16 mm and a tightening torque of 3.5 N.m. Embedding depth is 44 mm, overall depth 69 mm — that 69 mm is the dimension you need to check against gland-plate clearance or a shallow enclosure back wall. IP20 on the terminals, IP40 inside a modular enclosure. Pollution degree 2, so it's fine for normal indoor environments but not for washdown areas.