SURGE IMPEDANCE LOADING
Surge impedance of a line, Zo
A transmission line loaded to its surge impedance loading:
(i) has no net reactive power flow into or out of the line, and
(ii) will have approximately a flat voltage profile along its length.
For (i) to hold:
This means that there will be no net reactive power flow at surge-impedance loading.
For (ii) to hold:
This means that the line will have a flat voltage profile, i.e., no voltage drop.