The Siemens 3RK1303-6BS71-1AA0 is a reversing starter with solid-state switching contacts, designed for motor control in automated machinery where space is tight and the environment demands IP65 sealing. It handles reversing duty for three-phase motors up to 3 A in AC-3 category at 400 V — enough for small conveyors, positioning slides, or pump reversing stations that cycle infrequently (minimum 1 operation per hour). The 24 VDC control supply has a wide tolerance range of 20.4 to 28.8 V, so it holds in during dips that would drop a tighter-coil device. Two parameterizable digital inputs accept M12 connections for start/stop or direction commands, and the PROFIBUS DP interface lets a PLC orchestrate the reversing sequence without hardwired interlocks. Full motor protection is built in — short-circuit protection via fuses, and the solid-state output monitors for overload.
Footprint is 125 mm deep, 130 mm wide, 250 mm tall — a compact block that mounts via the ISO 23570 socket for main power infeed and load-side outgoing feeder. The supply voltage line-side connects through a hybrid plug that also carries the PROFIBUS DP communication, reducing cable clutter at the motor. Digital input signals use two M12 sockets (one per input), and the communication interface uses a hybrid plug/socket pair. No separate PROFINET option here — it's PROFIBUS DP only, so verify your controller's fieldbus before specifying.
Substance prohibitance compliance is documented as of May 1, 2012, covering RoHS and REACH requirements. No additional compliance documentation (UL, CSA, IEC) is listed in the spec record, so confirm with your quality team if those certifications are needed for your jurisdiction.