Ramp time is adjustable 0...120 seconds, with initial voltage during start settable 30...70 % and a step-down voltage special ramp of 100...30 %. That range covers soft starts for high-inertia loads like centrifuges or large fans, and the step-down ramp handles pump applications where pressure surge is a concern. Starting capacity is 3xIe for 15 s — enough for most standard squirrel-cage motors on a normal start cycle. Current limit function spans 1.5...7xIe. Control circuit runs on 24 V DC; main control supply accepts 100...250 V AC.
Signals and integration
Three signal relays are built in: run signal, fault signal, and overload signal, plus a by-pass signal relay. That's enough dry contacts to feed a PLC input card for run status, trip alarm, and overload warning without adding an external interface module. A red LED indicates fault; yellow indicates protection active. Communication is via a FiledBusPlug (Standard) — that's ABB's fieldbus adapter interface, meaning you can plug in a PROFIBUS, DeviceNet, or CANopen module depending on the network. The main circuit terminals are bars with a 12.5 mm hole diameter, sized for cable lugs on 1050 A conductors. Control circuit terminals accept rigid 1 x 2.5 mm² with a tightening torque of 0.5 N·m.
That's the one you want for a BOM freeze on a new panel design or a replacement for an existing PSTB1050 installation.