The ABB 1SFA899302R1105 is a PSCT-105 current transformer designed for use with PSTX-series soft starters. It provides the current feedback signal the soft starter needs to manage motor acceleration and protect against overloads — a critical link in the control loop for any PSTX-based motor starting panel.
What the PSCT-105 does in the circuit
The PSCT-105 mounts in the soft starter's control wiring, typically on the output side of the PSTX, to sense motor current. The transformer's secondary feeds the PSTX's current measurement input, enabling the soft starter to execute its starting ramp and protection curves. It is sized for the PSTX platform — verify the specific PSTX frame and motor FLA against the PSCT-105's ratio range before committing the BOM line.