The Siemens 3RK1300-1BS01-0AA3 is an EM 300 DS electromechanical direct starter designed for the ET 200X distributed I/O system. It is a motor-protective combination that integrates a bimetal overload relay and a contactor in one enclosure, rated for AC-3 duty at 0.75 kW on a 400 V supply. This unit is built for the ET 200X family, meaning it mounts directly onto the ET 200X motor starter system bus and communicates over PROFIBUS DP. It is not a standalone panel-mount starter — it is a modular slice in a distributed motor control center, typically deployed in conveyor, pump, or material-handling zones where the I/O and motor control live close to the machine. This suits it for washdown areas or outdoor installations where the starter is mounted directly on the machine frame rather than in a central cabinet.
The setting range of 1.4 to 2.0 A is the adjustable overload trip window. This is the first check for fit: the motor's full-load current must fall within this band. At 400 V AC-3, the starter is rated for 0.75 kW, which corresponds to a motor FLA of roughly 1.8 A — right in the middle of the adjustment range. The operating voltage is rated 400 to 500 V AC. The DC voltage type entry refers to the brake output, not the main coil. The maximum short-circuit breaking capacity (Icu) at 400 V is 50 A. This is the fault current the device can safely interrupt. The integrated motor brake output is a key differentiator: this variant includes a brake contact for externally supplied DC brakes, common on vertical-load conveyors or hoist axes. The 9-pole motor feeder and 9-pole power connection handle the brake wiring alongside the motor phases. Ambient temperature range during operation is 0 to 55 °C. Above 40 °C, derating of the overload curve may apply; the bimetal element responds to both current and ambient heat, so a hot enclosure can cause nuisance tripping.
Integration notes
Dimensions are 140 mm wide, 270 mm high, and 134 mm deep. This is a substantial block — it occupies one ET 200X slot width and extends 134 mm from the mounting surface. Verify clearance in the enclosure depth, especially if a cover or door is present. Main circuit connections use tab terminals, not screw clamps. This is standard for the ET 200X system; the mating connectors are part of the system bus infrastructure. If you are replacing a failed unit, the existing wiring harness should mate directly. PROFIBUS DP communication is built in. No AS-Interface. The bus address is set via the ET 200X bus interface module, not on the starter itself. The starter reports its status (overload trip, ready, fault) over the bus to the controller.