The high voltage lines are the ones with the highest voltage in an electrical system, those with the longest length and those that handle the largest power blocks. They interlink the different regions, exchanging energy in both directions.
In order to transport electric energy over long distances, minimizing losses and maximizing the power transported, it is necessary to raise the transport voltage. The voltage in the transmission circuits can range from 69 kV to 750 kV.
An increase in voltage means a decrease in the current flowing through the line, in order to carry the same power, and therefore the losses due to heating of the conductors and by electromagnetic effects. The higher the voltage, the less current and, consequently, the lower the energy loss, which is very important if one takes into account the fact that the high voltage lines tend to travel long distances.