The Siemens 3RW5227-3AC05 is a SIRIUS soft starter rated for a minimum motor current of 40.5 A across a voltage range of 200 to 600 V, meaning it handles standard low-voltage induction motors in that current band — not a 10 A pump, not a 200 A conveyor. The trip class defaults to CLASS 10A per IEC 60947-4-2, which limits the thermal stress during start to 10 seconds for a 7.5x locked-rotor current; you can reparameterize to 10E or 20E if the load profile (high-inertia fan, centrifuge) needs a longer ramp. The 40.5 A minimum is the smallest settable current, so it won't protect a motor drawing less than that — size down for fractional-horsepower loads. Mounting is screw-fixed on a vertical surface, rotatable ±90° and tiltable ±22.5° front-to-back, which gives flexibility in a crowded panel but still demands a 306 mm height, 185 mm width, and 203 mm depth footprint.
Fieldbus and control integration
This soft starter carries onboard PROFIBUS, Modbus RTU, Modbus TCP, EtherNet/IP, and PROFINET standard (with PROFIenergy support via a PROFINET communication module). That means it drops into most common fieldbus architectures without an external gateway — a controls integrator can map the starter's status and diagnostics directly into the PLC tag database. The analog output defaults to 4-20 mA but can be parameterized to 0-10 V through the High Feature HMI accessory, useful for feeding a remote meter or an analog input card that expects voltage. Remote reset is achieved by cycling the control supply voltage off and on — a standard field-service technique that avoids a physical pushbutton on the door. The error logbook is available only with special accessories, so if you need fault-history retrieval, factor that accessory into the BOM now rather than chasing it later.