The Siemens 5SL6640-7YA is a SENTRON miniature circuit breaker — 3-pole plus switched neutral, 40 A, C-curve, rated 6 kA breaking capacity per EN 60898 at 400 V AC. The 6 kA rating is the standard residential and light-commercial interrupting capacity for 400 V three-phase panels across Europe and markets that follow IEC 60898.
Snaps onto DIN rail, any mounting position, 4 modular-width units (72 mm wide). IP20 with the distribution board cover fitted, which is the usual enclosure requirement for residential and infrastructure panels. No supplementary device slot on this variant, so any auxiliary contact or shunt trip needs a separate breaker position.