The Siemens 3RK1300-1FS01-0AA4 is an EM 300 DS direct starter from the SIRIUS family, designed for the ET 200X distributed I/O system. It's an electromechanical direct-on-line starter with a bimetal overload relay, rated for AC-3 duty at 1.9 kW at 400 V and a setting range of 3.5 to 5.0 A. The IP65 enclosure means this unit is built to handle washdown environments — think food processing, packaging lines, or any spot where a hose-down is part of the routine. The integrated motor brake output handles DC 500 V/1 A for internally supplied brakes, saving you an external contactor on the brake circuit.
What the ratings mean for the panel
At 140 mm wide and 270 mm tall, this starter occupies a standard footprint for the ET 200X family. The 134 mm depth is important for shallow enclosures — verify your gland plate clearance before committing the BOM line. Tab terminals on the main current circuit accept standard fork or ring lugs; the 9-pole motor feeder and 9-pole power connection are pre-configured for the ET 200X backplane. Operating voltage is 400 to 500 V AC, so it's happy on 400 V or 480 V systems without a transformer tap change. Short-circuit protection is handled by circuit-breakers (the unit is designed for coordination with them, not fuses). The maximum short-circuit breaking capacity at 400 V is 50 A — that's the fault current the bimetal and contactor can safely interrupt without welding. Ambient temperature range is 0 to 55 °C during operation; if your panel sits in a hot machine cabinet or near a furnace line, you'll need to derate or add ventilation above that ceiling.
PROFIBUS DP and brake integration
This starter communicates over PROFIBUS DP, making it a drop on the fieldbus for remote start/stop and fault feedback. No AS-interface on this variant — the protocol is fixed at PROFIBUS. The integrated brake output is a real time-saver on the wiring side: it's rated for DC 500 V/1 A, which covers most small holding brakes on motors up to 1.9 kW. The brake contact is internally wired, so you don't need a separate interposing relay. Equipment marking per DIN EN 61346-2 is Q, meaning it's classified as a switching device in the schematic.