The ABB PST50 1SFA895005R7020 is a soft starter for three-phase induction motors, rated 50 A inline (Ie) and 85 A inside-delta connection, delivering 45 kW at 400 V in delta. It carries built-in electronic overload protection (current limit adjustable 1.5–7× Ie) and a programmable ramp time from 0 to 120 seconds — enough to handle high-inertia loads like conveyors or pumps without mechanical shock. Control supply is 100–250 V AC; the unit also accepts a separate 24 V DC control circuit for logic isolation.
The 50 A inline rating is the figure to match against your motor FLA for standard three-wire connection. The 85 A inside-delta rating applies when the starter is wired in the delta legs of a wye-delta motor — that configuration delivers 45 kW at 400 V. If your motor is smaller, the 115 % service factor gives headroom for occasional overload without nuisance tripping. Ramp time spans 0–120 seconds, with initial voltage adjustable 30–70 % and a step-down voltage ramp from 100–30 %. That range covers soft start and soft stop for most pump, fan, and conveyor applications. The built-in electronic overload eliminates the need for a separate overload relay — one less component to size and wire.
Integration notes
Main circuit terminals accept rigid 1 x 10…95 mm² cable; control and supply wiring is 1 x 2.5 mm². Tightening torque for the control circuit is 0.5 N·m. The unit includes run, fault, bypass, and overload signal relays — four dry contacts for PLC or HMI feedback without extra interface relays. Communication is via a FiledBusPlug (standard) — the optional fieldbus adapter plugs into the front slot for PROFIBUS, DeviceNet, or Modbus connectivity. The analog output is 0–10 V, usable for speed or current signal to a drive or meter.