I know voltage levels and line lengths of high-voltage transmission lines and I am looking for a rough estimation of the maximum active-power transmission capacity during normal operation. By normal operation I mean power levels that can be sustained over long durations. I understand that many factors are impacting this and that a 1-to-1 map from voltage to active power level is hard to give. But I am looking for rough estimations only, and I am happy with any upper-bound, lower-bound, or range estimations.
An example would be: out of my window, I can see a transmission line and all I know about it is that it's a single-circuit 220 kV line. In which range will the active power capacity of this line be?