Soft starter for heavy motor starts
The ABB PSTB1050 (1SFA895020R7000) is a soft starter rated for 1050 A in-line connection, delivering 560 kW at 400 V. It handles motors up to 690 V AC and includes built-in electronic overload protection, so you can omit a separate overload relay from the panel. Ramp time is adjustable from 0 to 120 seconds, with an initial voltage during start configurable between 30% and 70%. The current limit function spans 1.5 to 7 times the rated current Ie, giving you control over inrush on high-inertia loads like conveyors or crushers. Communication uses a standard FieldBusPlug interface, and the control circuit accepts 24 V DC. Three signal relays are built in — run, fault, and bypass — plus an overload signal relay and a red LED for fault indication.
Integration notes
Main circuit terminals are bars with a 12.5 mm hole diameter; control circuit terminals accept rigid 1 x 2.5 mm² wire with a tightening torque of 0.5 N·m. The supply circuit connects via rigid 1 x 2.5 mm² as well. Ambient operating temperature range is 0 to +50 °C. The inside-delta connection option boosts capacity to 1810 A and 1000 kW at 400 V, useful for retrofit into existing delta-configured motor windings. A switch for inside-delta connection is included on the unit.