The ABB 1SFA899302R1840 is a PSCT-840 current transformer designed for use with PSTX soft starters. It is part of the PSCT product family and is classified as suitable for softstarter applications. This current transformer provides the current sensing input that the PSTX soft starter uses to monitor motor load and adjust the firing angle for smooth acceleration. If you are maintaining an installed PSTX line, this is the specific CT that feeds the starter's current feedback.
Compatibility Note
The PSCT-840 is listed as suitable for PSTX soft starters. It is not a universal CT — it is specifically matched to the PSTX series for current sensing and feedback. Verify that your PSTX model expects the PSCT-840 (the technical information code PSCT-840 is on the nameplate).