The ABB PST85 1SFA894008R7000 is a softstarter rated 85 A in-line connection and 147 A inside delta, delivering 45 kW at 400 V in-line or 75 kW inside delta. The inside-delta wiring reduces the current through the thyristors by a factor of √3, so the same unit handles a larger motor when wired that way — a common trick for squeezing more power out of a given frame size. The ramp time is adjustable from 0 to 120 seconds, which covers most pump, fan, and conveyor acceleration profiles. Initial voltage during start is settable from 30 to 70 %, and a separate step-down voltage special ramp (100 to 30 %) handles deceleration or soft stop. The current limit function (1.5 to 7× Ie) lets you clamp inrush for weak supply lines or sensitive loads.
Control and protection
Control supply voltage is 100–250 V AC; the control circuit also accepts 24 V DC for logic-level interfacing. Built-in electronic overload protection eliminates the need for a separate overload relay — the softstarter itself handles motor thermal protection. Four signal relays (run, fault, bypass, overload) give discrete feedback to the PLC or DCS. Communication is via a standard FieldBusPlug, so it connects to a fieldbus network through an optional plug-in module (PROFIBUS, DeviceNet, Modbus RTU, etc.). The main circuit terminals are bars with an 8.5 mm hole; control circuit terminals accept 1 × 2.5 mm² rigid wire at 0.5 N·m torque.