The ABB PSTX1250 soft starter (order code 1SFA898221R7000) is a current-production motor starting solution rated for 208...690 V AC operational voltage at 50/60 Hz. Its primary function is auto phase sequence detection, meaning it checks and corrects the phase rotation before the motor starts — a useful safeguard on installations where phase rotation is unpredictable or where a reversed rotation could damage driven equipment.
Ramp and protection depth
Ramp time is adjustable from 1 to 120 seconds, giving you a wide window to match the acceleration profile of conveyors, pumps, or compressors. The built-in electronic overload protection covers both start and run phases with separate overload settings — a dual-overload scheme that prevents nuisance tripping on high-inertia starts while still protecting the motor during steady-state operation. Protection functions include locked rotor, phase reversal, earth fault / ground fault, under- and over-voltage, current imbalance, and too-long start time. The unit also monitors PT-100 and PTC inputs for direct motor thermal feedback. A full set of warning outputs (current imbalance, underload, fan fault, EOL, etc.) feeds the fieldbus or local LEDs.
Fieldbus and I/O
Communication options cover Modbus-RTU, Modbus-TCP, Ethernet-IP, EtherCAT, DeviceNet, CANopen, Profibus, Profinet, BACnet-IP, and BACnet-MSTP — essentially every major industrial protocol, so it drops into existing control architectures without a gateway. Analog outputs are configurable as 0...10 V, 0...20 mA, or 4...20 mA for speed or torque feedback to a PLC or drive.
Control supply and wiring
Control supply voltage accepts 100...250 V AC; the control circuit itself runs on 24 V DC. Main circuit terminals are bars with a tightening torque of 45 N·m — expect bus-bar or large-cable lugs. The unit supports inside-delta connection, which reduces the current rating of the bypass contactor in delta-configured motors.