What it is and what it does
The Siemens 3RK1300-1BS01-0AA4 is an electromechanical direct starter from the EM 300 DS family, designed for the ET 200X distributed I/O system. It integrates a bimetal motor protection relay with a setting range of 1.4...2.0 A and is rated for AC-3 duty at 0.75 kW at 400 V, meaning it switches three-phase induction motors up to that power under normal starting conditions. The part includes a motor brake output for internally supplied DC brakes rated at 500 V / 1 A, and communicates over PROFIBUS DP for remote start/stop and diagnostics.
Key ratings and what they mean for fit
The 1.4...2.0 A setting range (full-scale 2 A) directly sets the motor full-load current trip point — match this to the motor nameplate FLA. The AC-3 rating at 0.75 kW / 400 V covers standard squirrel-cage motor starts; the 50 A short-circuit breaking capacity (Icu at 400 V) means the integrated circuit-breaker can safely clear a fault up to that level without upstream damage. IP65 protection allows installation in washdown or dusty environments — the housing seals against water jets and dust ingress, suitable for food-and-bev or material-handling lines. The operating voltage range of 400...500 V AC covers 400 V and 480 V nominal supplies common in industrial plants. Ambient temperature range is 0...55 °C during operation; derate the motor current if the enclosure ambient exceeds 40 °C. The part uses tab terminals for the main current circuit, so plan for fast-on connectors rather than screw clamps.
Where it fits in the system
This direct starter mounts to the ET 200X remote I/O station, not a standalone DIN rail — it plugs into the system backplane and connects via a 9-pole motor feeder and 9-pole power connection. The PROFIBUS DP interface handles control and feedback, so the starter is addressed and monitored from the PLC without hardwired start/stop circuits. The brake output is intended for internally supplied DC brakes (500 V / 1 A), common on holding brakes for vertical-axis motors.