The ABB PSTB1050 soft starter (1SFA894020R7020) is sized for a 1050 A in-line motor load, which translates to 560 kW at 400 V — the rating that governs the BOM line for a pump, fan, or conveyor drive. The 0 to 120 second ramp time covers soft start and soft stop profiles; set the initial voltage during start between 30 and 70 % to match the load's breakaway torque without a mechanical shock. Built-in electronic overload protection (1.5 to 7x Ie current limit function) means you skip the separate overload relay — one device handles both starting and running protection. For inside-delta configurations, the same unit delivers 1810 A and 1000 kW at 400 V — a useful headroom when the motor windings are reconnected for higher starting torque. The 24 V DC control circuit voltage interfaces directly with standard PLC or relay logic; the 100-250 V AC control supply powers the internal electronics without a separate transformer.
Main circuit terminals are bars with a 12.5 mm hole diameter — expect lug-type connections sized for the 1050 A continuous current. Control circuit wiring accepts 1 x 2.5 mm² rigid conductors, tightened to 0.5 N·m. The FieldBusPlug communication interface (standard) connects to the automation network via a plug-in module; no fieldbus wiring to the main terminal block. The unit includes run, fault, bypass, and overload signal relays — all dry contacts for the PLC to monitor start complete, trip, and bypass engagement. The red LED signals a fault condition; the yellow LED indicates protection active. Ambient operating temperature is 0 to +50 °C, so panel placement should avoid heat sources like adjacent drives or transformers.