Softstarter for heavy motor loads
The ABB PSTB840 1SFA895019R7020 is a softstarter rated 840 A in-line connection (Ie) and 1455 A inside-delta, delivering 450 kW at 400 V or 800 kW in the delta configuration. That current class puts it squarely on large pumps, compressors, conveyors, and crushers — loads where across-the-line starting would hammer the supply and the mechanical train. Built-in electronic overload protection eliminates the need for a separate overload relay, saving a DIN-rail slot and reducing wiring. The current limit function adjusts 1.5–7× Ie, letting you tune the start to the load — set it low for a centrifugal pump, higher for a loaded conveyor. The 0–120 s ramp time and initial voltage 30–70 % give you a wide window to dial in the acceleration profile. Step-down voltage special ramp (100–30 %) handles the deceleration side for loads that shouldn't coast.
Control and integration
Control supply accepts 100–250 V AC; the control circuit also takes 24 V DC for PLC compatibility. Analog output 0–10 V feeds a speed or current signal back to the controller. Communication is via a standard FieldBusPlug — the ABB fieldbus adapter interface, so you can drop in PROFIBUS, DeviceNet, or Ethernet adapters without rewiring the base unit. Three signal relays are built in: run, fault, and bypass, plus an overload signal relay. That gives the PLC direct status feedback without extra interposing relays. The inside-delta connection switch is onboard, so you can rewire the motor windings for the higher delta current without an external contactor set. Main circuit terminals are bars with a 12.5 mm hole — expect lug-type connections. Control circuit torque is 0.5 N·m. Ambient operating range is 0 to +50 °C.