This function computes the overall resistance of a cable.
When the voltage level is medium or high, the cables have a DC resistance that needs to be corrected to account for the effects cause by the AC voltage. The correction is
R = lCABLE RDC fCORR(s, m),
where RDC is the characteristic DC resistance per unit length, lCABLE is the length of the cable, and fCORR(s, m) is a function that corrects the DC value and depends on the size of the cable s and its material m. See Buildings.Electrical.Transmission.Functions.R_AC_correction for more details.