The Siemens SIRIUS 3RK1325-6KS71-3AA0 is a reversing motor starter designed for direct-on-line reversing of three-phase motors up to 0.75 kW at 400 V (0.7 hp at 460/480 V). The AS-Interface protocol on board handles both control and diagnostics over a single two-wire cable, so no separate control wiring to a PLC cabinet is needed. Four digital inputs and one digital output are available for local sensors and status feedback.
The trip class is selectable between CLASS 5, 10, 15, and 20. That range covers fast-acting protection for short-acceleration pumps (CLASS 5) through to high-inertia loads like centrifuges (CLASS 20). The unit is a reversing starter — it includes two contactors mechanically interlocked so the motor can be run forward and reverse without external interlocking relays. Supply voltage is 24 V DC (20.4 to 28.8 V range, max 31.6 V), which is the standard control voltage for most modern PLC and fieldbus systems. ON-delay is 25 ms, OFF-delay 35 ms — these are the response times of the internal logic, not the main contactor dropout. For the main circuit, the power connection uses a HAN Q4/2 plug (ISO 23570), so verify your panel has the mating connector or order it separately.
Mounting is by screw fixing (no DIN-rail clip). The unit can be installed vertically, horizontally, or flat — but the manufacturer recommends horizontal orientation for best thermal performance. Dimensions are 294 mm wide, 215 mm high, 159 mm deep — a substantial footprint, so check your gland plate and sidewall clearance before committing. Vibration resistance is 7 mm / 2g; shock resistance is 12g for 11 ms — typical for machine-mounted gear near presses or conveyors.