It protects against overcurrent and short-circuit in 400 V AC circuits, with a breaking capacity of 10 kA per EN 60898 and 35 kA per IEC 60947-2 — the higher figure is the one that governs industrial panel coordination.
At 3 A, this is a low-current branch or control-circuit protector, not a main feeder. The 35 kA IEC 60947-2 rating is the industrial SCCR you coordinate upstream; the 10 kA EN 60898 figure is the residential/commercial rating. For DC circuits, it handles up to 72 V with 15 kA breaking capacity — useful for railway auxiliary supplies.