The Siemens SIRIUS 3RA2120-1KH24-0AP0 is a direct on-line starter in size S0, designed for snapping onto 60 mm busbar systems. It integrates a contactor and overload relay into one unit, providing motor starting and overload protection in a single footprint. The main circuit connects via spring-loaded terminals, saving wiring time compared to screw clamps, and the unit mounts vertically on the busbar.
Snaps directly onto a 60 mm busbar system — no DIN rail adapter needed. Dimensions are 45 mm wide × 260 mm high × 165 mm deep, fitting standard S0 feeder footprints.
Ratings and motor sizing
At 400 V it is rated for 5.5 kW (7.5 hp at 460/480 V, 10 hp at 575/600 V). At 230 V it handles 2 hp; at 200/208 V it handles 3 hp. The supplied contactor is 3RT2024-2AP00 and the link module is 3RA2921-2AA00 — these are the factory-matched components for this starter assembly.