The Siemens 3RK1300-0FS01-1AA1 is an electromechanical reversing starter from the SIRIUS EM 300 RS family, designed for ET 200X distributed I/O environments. It combines a reversing contactor, bimetal overload relay, and PROFIBUS DP communication in a single IP65 enclosure — meaning it mounts directly on the machine or in a field-distribution box, not in a central cabinet. The setting range of 0.35 to 0.5 A covers small motors up to 0.12 kW at 400 V AC-3 duty, so it handles reversing loads like conveyor drives, valve actuators, or small hoists where direction change is frequent.
The unit ships as a complete reversing starter assembly — contactor pair, bimetal overload, PROFIBUS DP interface, and a motor brake output rated DC 24 V / 3 A for externally supplied brakes. Main circuit connections use tab terminals; the 9-pole motor feeder and 9-pole power connection are integral. No separate contactor or overload to order — the kit is complete for a reversing motor branch with brake control.
The 0.35 to 0.5 A setting range on the bimetal overload matches the full-load current of a 0.12 kW motor at 400 V AC-3. The maximum short-circuit breaking capacity (Icu) at 400 V is 50 A — this is the fault current the integrated short-circuit protection (circuit-breakers) can interrupt without damage. Operating voltage is rated 400 to 500 V, so it works on 400 V or 480 V line supplies.
At 140 mm wide, 270 mm high, and 134 mm deep, the unit occupies a compact footprint for a reversing starter with integrated bus communication. The IP65 enclosure is designed for direct machine mounting or field-distribution boxes — no DIN-rail required. Ambient operating temperature range is 0 to 55 °C, so it handles typical industrial environments without derating.