The Schneider Electric A9KS15440BQ is an Acti 9K Isolator, a 4-pole switch rated for 40 A at 415 V AC, supplied as a set of three units.
The 40 A rating at 415 V AC defines the continuous current-carrying capacity and the voltage withstand for the isolating gap. In a distribution board, this isolator sits upstream of a 40 A final subcircuit — typically feeding a group of socket outlets, a small lighting distribution, or a fixed appliance. The 4-pole switching (3 phases + neutral) is required where the neutral must be isolated for safe access, per IEC 60364-5-53.