The Schneider Electric A9KF71240BQ is a 40 A miniature circuit breaker from the Acti9 K60 series, 2-pole, C-curve, rated for AC networks at 50/60 Hz. It protects downstream wiring and loads against overloads (thermal-magnetic trip) and short-circuits up to 10 kA Icn at 415 V AC, per EN/IEC 60898-1. The C-curve magnetic trip operates at 5 to 10 times the rated current (200 to 400 A), which suits it for mixed resistive and moderate inductive loads — think general distribution panels feeding lighting, small motor circuits, or socket outlets where inrush is present but not extreme.
Snaps onto a 36 mm wide DIN rail — standard 4-module pitch (9 mm per pole, 2 poles protected). Tightening torque is 3.5 N.m; strip length 14 mm. Pollution degree 2, overvoltage category II — standard for fixed-installation final circuits.