The Siemens 5SL6415-8CC is a 4-pole miniature circuit breaker from the SENTRON 5SL6 series, rated at 400 V with a 6 kA breaking capacity and a D tripping characteristic at 1.6 A. This is a DIN-rail mounted device for panel integration, sized for protecting branch circuits with high inrush loads — typical for motor starters or transformer primaries where the D-curve's wider magnetic trip threshold avoids nuisance tripping on start-up.
The D-curve (10-20x In magnetic trip) is the deciding spec for fit: it allows the 1.6 A rating to pass motor inrush without tripping, while still protecting against hard shorts. Four poles cover three-phase plus neutral, or can be used as a four-pole single-phase isolator.