The SFT Calculator is provided so the PF and PFQ can be estimated for lines that don't exist on the grid yet. As explained in How EMO models SFT constraints these two values are used be EMO to generate SFT constraints, so they will be needed if a line is added to a forecast and needs to be included in the SFT modelling.
The SFT Calculator is opened from the Data menu. A dialog box appears from which an existing line can be chosen to provide starting values in the calculator. Once the calculator is open the conductor properties and the cable configuration can be changed. The resulting thermal limit and PF and PFQ values will be automatically updated as changes are made.