What this PSTX570 soft starter does on the line
The ABB PSTX570 soft starter (order code 1SFA898217R7000) handles motor starting with auto phase sequence detection — it checks the incoming phase rotation before the motor ever sees power, so a swapped phase doesn't send a conveyor or pump running backwards. Rated 208 to 690 V AC at 50/60 Hz, it carries a 200 HP three-phase motor at 200-208 V under UL/CSA. The built-in electronic overload replaces a separate overload relay, saving a DIN-rail slot and a wiring step.
Ramp and protection — what the settings mean for the motor
The ramp time adjusts from 1 to 120 seconds. That range covers soft starts for everything from a quick-ramp centrifugal pump to a long-ramp conveyor with a heavy belt. Initial voltage during start is settable from 10 to 99 %, and a separate step-down special ramp lets you dial in 100 to 10 % for applications that need a two-stage deceleration. Protection is comprehensive: electronic overload (with separate overload curves for start and run), earth fault, locked rotor, phase reversal, under/over voltage, current imbalance, and PTC/PT-100 thermistor inputs for motor temperature monitoring. The unit also generates warnings for current imbalance, underload, over/under voltage, THD(U), thyristor overload, and fan failure — so the control system knows about developing problems before they trip.
Communication and integration
This soft starter speaks ten fieldbus protocols natively: Modbus RTU, Modbus TCP, Ethernet/IP, EtherCAT, DeviceNet, CANopen, Profibus, Profinet, BACnet IP, and BACnet MSTP. That breadth means it drops into most plant networks without a gateway. The control circuit runs on 24 V DC, separate from the main circuit supply which takes 100-250 V AC. Three signal relays (run, fault, bypass, overload) give dry-contact feedback to a PLC or DCS without extra I/O.