Softstarter for motor starting — PST142, 142 A in-line
The ABB PST142 softstarter (1SFA895010R7000) is rated 142 A in-line connection and 245 A inside-delta, with a main circuit voltage of 400–690 V AC. That inside-delta rating lets you start motors up to 132 kW at 400 V while using a physically smaller unit — the current passes through the thyristors only during start/stop, not during run, so the bypass contactor carries the full load current. Built-in electronic overload protection eliminates the need for a separate overload relay.
Ramp and starting parameters
Ramp time is adjustable 0–120 s, initial voltage 30–70 % of line, and a step-down special ramp from 100 % down to 30 %. Current limit can be set 1.5–7× Ie, and starting capacity is 3× Ie for 15 s. The 115 % service factor means the softstarter can run continuously at 15 % above rated current without tripping — useful for high-inertia loads that take longer to accelerate.
Control and communication
Control supply voltage is 100–250 V AC; a separate 24 V DC control circuit is available for the logic. Communication is via a standard FieldBusPlug — the softstarter accepts ABB's fieldbus adapter modules (PROFIBUS, DeviceNet, Modbus RTU, etc.) plugged directly into the front. Signal relays for run, fault, bypass, and overload are all present, plus a red fault LED and yellow protection LED. Main circuit terminals are bars with an 8.5 mm hole; control circuit terminals accept 1 x 2.5 mm² rigid wire at 0.5 N·m.