The Siemens 3RK1300-1AS01-1AA1 is an electromechanical reversing starter from the SIRIUS EM 300 RS family, designed for ET 200X distributed I/O environments. It's a single enclosure that combines a reversing contactor, bimetal overload relay, and PROFIBUS DP interface — one part number instead of three separate components on the DIN rail. The bimetal motor protection (setting range 1.1...1.6 A) covers small motors up to 0.55 kW at 400 V AC-3 duty, which is the standard rating for a 0.55 kW three-phase induction motor on a conveyor or pump. Rated operating voltage is 400...500 V AC, so it works on 400 V and 480 V line supplies common in European and North American industrial panels. That's one less enclosure to spec and wire.
If you're filling a spare for a line that uses ET 200X drops, this is the direct fit — no rewiring, no adapter plate.
That's a compact footprint for a reversing starter with integrated bus and brake supply — it fits in a standard 300 mm deep cabinet with room for wiring ducts. The IP65 rating means it can also mount outside the cabinet on a machine frame, which saves panel space entirely.
Short-circuit coordination and ambient limits
Maximum short-circuit breaking capacity (Icu) at 400 V is 50 A, coordinated with circuit-breakers for short-circuit protection. The electromechanical switching contacts are rated for AC-3 duty (motor starting), not resistive loads.