The Siemens 3RK1300-1AS01-0AA1 is an EM 300 DS electromechanical direct starter designed for the ET 200X distributed I/O system. It's a self-contained motor starting and protection unit that combines a contactor, overload relay (bimetal type), and short-circuit protection (circuit-breakers) in one enclosure. The setting range is 1.1...1.6 A, and at AC-3 duty on a 400 V supply it's rated for 0.55 kW motor loads. This is a direct-on-line starter, meaning it connects the motor directly to the supply line — no soft-start or ramp. The electromechanical switching contact provides a positive, welded-immune isolation when open, which matters for safety circuits where you need to verify the gap. The unit includes a motor brake output (DC 24 V / 3 A) for externally supplied brakes, making it suitable for applications like vertical-axis conveyors or hoists where holding torque must be maintained when power is removed.
The enclosure measures 140 mm wide, 270 mm high, and 134 mm deep, with an IP65 protection class. That IP65 rating means the housing is dust-tight and protected against water jets — it can be mounted directly on machine frames or in washdown zones without a separate cabinet, as long as the cable glands are properly sealed. The main current circuit connects via tab terminals, which are common for this class of distributed starter. The unit communicates over PROFIBUS DP, so it integrates into a Siemens ET 200X station as a bus-addressed slave device. No AS-interface on this variant. Operating ambient temperature range is 0... 55 °C, which covers most industrial floor conditions but not freezer or high-temp oven environments. The supply voltage is 400... 500 V AC.