The Siemens 3RA2225-1KB24-0BB4 is a SIRIUS non-fused reversing motor starter in size S0, combining a contactor and thermal overload relay in one package for forward/reverse control of three-phase motors. Rated at 5.5 kW at 400 V AC-3 (7.5 hp at 460/480 V, 10 hp at 575/600 V), it handles reversing duty on pumps, conveyors, and other loads that need direction change. Coil voltage is 24 VDC, so it integrates directly into a 24 VDC control circuit without an interposing relay.
Snap-on fastening on 35 mm DIN rail, vertical mounting position only. The S0 footprint is 90 mm wide, 130 mm deep, 265 mm tall — plan for that height in shallow enclosures. Clearance requirements: 30 mm upwards, 10 mm forwards, 10 mm downwards, 9 mm at the side, 0 mm backwards — tight side-by-side stacking is possible. The unit ships with a 3RT2024-1BB40 contactor, a 3RA2921-1BA00 link module, and a 3RA2922-1AA00 busbar adapter — all pre-assembled, so no separate ordering of those subcomponents.