The Schneider Electric A9KF71120BQ is a 1-pole Acti9 K60 miniature circuit breaker rated 20 A with a C-curve trip characteristic. It sits on a DIN rail, occupies 2 x 9 mm pitches (18 mm wide), and provides 10 kA breaking capacity at 240 V AC per EN/IEC 60898-1.
The C-curve (magnetic trip at 5–10 x In) means this breaker tolerates the inrush from motor starters, small transformers, and lighting ballasts without nuisance tripping — it's the standard choice for general-purpose distribution circuits, not for purely resistive loads where a B-curve would do. The 20 A rating and 1-pole format suit a single-phase branch circuit feeding outlets, lighting, or a small machine. Thermal-magnetic trip technology combines a bimetal strip for overload protection and a solenoid for short-circuit response; no electronics to fail or drift. If your panel's prospective fault current exceeds that, you step up to an industrial-model MCB or a higher-rated Acti9 variant. IP20 means finger-safe terminals but no protection against water — keep it inside the enclosure.
Deployment context
Snap onto a DIN rail in the distribution board. The 18 mm width (2 modules) fits standard cutouts. The toggle actuator gives clear visual indication of the contact position.