25.5 A minimum — sets the floor for motor sizing
The 3RW5225-1TC04: This SIRIUS soft starter has a minimum operating current of 25.5 A, meaning the connected motor's full-load current must be at or above that value for the unit to regulate startup torque properly. Below that floor, the current sensing loses accuracy and the trip class timing may not hold. Rated voltage covers 200 to 480 V, so it fits standard low-voltage three-phase supplies across North America (208/240/480 V) and Europe (230/400 V) without a separate transformer tap.
Trip class 10A — 10 seconds to manage heat buildup
Trip class is set to CLASS 10A by default, with selectable 10E and 20E options per IEC 60947-4-2.
Fieldbus onboard — PROFIBUS, Modbus, EtherNet/IP, PROFINET
The unit ships with PROFIBUS, Modbus RTU, Modbus TCP, EtherNet/IP, and PROFINET communication. No separate gateway module is needed for these four protocols — the soft starter talks directly to the PLC or SCADA. PROFIenergy is supported via the PROFINET standard module, allowing energy management data collection during idle phases.
Pump-specific features — Soft Torque and Pump Ramp Down
Soft Torque reduces the starting torque below the motor's locked-rotor torque, which helps on conveyors or pumps where a hard start can damage the belt or cause water hammer. Pump Ramp Down controls deceleration to prevent pressure surges when stopping a centrifugal pump — the unit ramps voltage down gradually rather than cutting power instantly. Auto-reset and remote reset by cycling the control supply are standard, so the starter can re-close after a fault without a manual pushbutton visit — useful for remote or unmanned stations.